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Title: The Foundations of the Origin of Species

Author: Charles Darwin

Editor: Sir Francis Darwin

Release date: September 22, 2007 [eBook #22728]

Language: English

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*** START OF THE PROJECT GUTENBERG EBOOK THE
FOUNDATIONS OF THE ORIGIN OF SPECIES ***

THE FOUNDATIONS OF THE
ORIGIN OF SPECIES
CAMBRIDGE UNIVERSITY PRESS
London: FETTER LANE, E.C.
C. F. CLAY, Manager

Edinburgh: 100, PRINCES STREET
ALSO
London: H. K. LEWIS, 136, GOWER STREET, W.C.

Berlin: A. ASHER AND CO.

Leipzig: F. A. BROCKHAUS

New York: G. P. PUTNAM’S SONS

Bombay and Calcutta: MACMILLAN AND Co., Ltd.

All rights reserved

From a photograph by Maull & Fox in 1854

THE FOUNDATIONS OF THE
ORIGIN OF SPECIES
TWO ESSAYS
WRITTEN IN 1842 AND 1844

by

CHARLES DARWIN

Edited by his son
FRANCIS DARWIN
Honorary Fellow of Christ's College

Cambridge:
at the University Press
1909

Astronomers might formerly have said that God ordered each
planet to move in its particular destiny. In same manner God orders
each animal created with certain form in certain country. But how
much more simple and sublime power,—let attraction act according to
certain law, such are inevitable consequences,—let animal«s» be
created, then by the fixed laws of generation, such will be their
successors.
From Darwin’s Note Book, 1837, p. 101.

TO THE MASTER AND FELLOWS
OF CHRIST’S COLLEGE, THIS
BOOK IS DEDICATED BY THE
EDITOR IN TOKEN OF RESPECT
AND GRATITUDE

CONTENTS

ESSAY OF 1842

PAGES

Introduction xi

PART I

§ i. On variation under domestication, and on the principles of
selection 1
§ ii. On variation in a state of nature and on the natural means of
selection 4
§ iii. On variation in instincts and other mental attributes 17

PART II

§§ iv. and v. On the evidence from Geology. (The reasons for
combining the two sections are given in the Introduction) 22
§ vi. Geographical distribution 29
§ vii. Affinities and classification 35
§ viii. Unity of type in the great classes 38
§ ix. Abortive organs 45
§ x. Recapitulation and conclusion 48

ESSAY OF 1844

PART I

CHAPTER I
ON THE VARIATION OF ORGANIC BEINGS UNDER
DOMESTICATION; AND ON THE PRINCIPLES OF SELECTION.

Variation
On the hereditary tendency
Causes of Variation
On Selection
Crossing Breeds
Whether our domestic races have descended from one or more wild
stocks
Limits to Variation in degree and kind
In what consists Domestication
Summary 57-80

CHAPTER II
ON THE VARIATION OF ORGANIC BEINGS IN A WILD STATE; ON
THE NATURAL MEANS OF SELECTION; AND ON THE
COMPARISON OF DOMESTIC RACES AND TRUE SPECIES.

Variation
Natural means of Selection
Differences between “Races” and “Species”:—first, in their trueness or
variability
Difference between “Races” and “Species” in fertility when crossed
Causes of Sterility in Hybrids
Infertility from causes distinct from hybridisation
Points of Resemblance between “Races” and “Species”
External characters of Hybrids and Mongrels
Summary
Limits of Variation 81-111

CHAPTER III
ON THE VARIATION OF INSTINCTS AND OTHER MENTAL
ATTRIBUTES UNDER DOMESTICATION AND IN A STATE OF
NATURE; ON THE DIFFICULTIES IN THIS SUBJECT; AND ON

ANALOGOUS DIFFICULTIES WITH RESPECT TO CORPOREAL
STRUCTURES.

Variation of mental attributes under domestication
Hereditary habits compared with instincts
Variation in the mental attributes of wild animals
Principles of Selection applicable to instincts
Difficulties in the acquirement of complex instincts by Selection
Difficulties in the acquirement by Selection of complex corporeal
structures 112-132

PART II
ON THE EVIDENCE FAVOURABLE AND OPPOSED TO THE VIEW
THAT SPECIES ARE NATURALLY FORMED RACES, DESCENDED
FROM COMMON STOCKS.

CHAPTER IV
ON THE NUMBER OF INTERMEDIATE FORMS REQUIRED ON THE
THEORY OF COMMON DESCENT; AND ON THEIR ABSENCE IN A
FOSSIL STATE 133-143

CHAPTER V
GRADUAL APPEARANCE AND DISAPPEARANCE OF SPECIES. 144-
150

Gradual appearance of species
Extinction of species

CHAPTER VI
ON THE GEOGRAPHICAL DISTRIBUTION OF ORGANIC BEINGS IN
PAST AND PRESENT TIMES.

SECTION FIRST 151-174

Distribution of the inhabitants in the different continents
Relation of range in genera and species
Distribution of the inhabitants in the same continent
Insular Faunas
Alpine Floras
Cause of the similarity in the floras of some distant mountains
Whether the same species has been created more than once
On the number of species, and of the classes to which they belong in
different regions

SECOND SECTION 174-182

Geographical distribution of extinct organisms
Changes in geographical distribution
Summary on the distribution of living and extinct organic beings

SECTION THIRD 183-197

An attempt to explain the foregoing laws of geographical distribution,
on the theory of allied species having a common descent
Improbability of finding fossil forms intermediate between existing
species

CHAPTER VII
ON THE NATURE OF THE AFFINITIES AND CLASSIFICATION
OF ORGANIC BEINGS. 198-213

Gradual appearance and disappearance of groups
What is the Natural System?
On the kind of relation between distinct groups
Classification of Races or Varieties
Classification of Races and Species similar
Origin of genera and families

CHAPTER VIII
UNITY OF TYPE IN THE GREAT CLASSES; AND MORPHOLOGICAL
STRUCTURES.

Unity of Type
Morphology
Embryology
Attempt to explain the facts of embryology
On the graduated complexity in each great class
Modification by selection of the forms of immature animals
Importance of embryology in classification
Order in time in which the great classes have first appeared 214-230

CHAPTER IX
ABORTIVE OR RUDIMENTARY ORGANS.

The abortive organs of Naturalists
The abortive organs of Physiologists
Abortion from gradual disuse 231-238

CHAPTER X
RECAPITULATION AND CONCLUSION.

Recapitulation
Why do we wish to reject the Theory of Common Descent?
Conclusion 239-255
Index 257
Portrait frontispiece
Facsimile to face p. 50

INTRODUCTION
We know from the contents of Charles Darwin’s Note Book of 1837 that
he was at that time a convinced Evolutionist{1}. Nor can there be any doubt
that, when he started on board the Beagle, such opinions as he had were on
the side of immutability. When therefore did the current of his thoughts
begin to set in the direction of Evolution?
We have first to consider the factors that made for such a change. On his
departure in 1831, Henslow gave him vol. i. of Lyell's Principles, then just
published, with the warning that he was not to believe what he read{2}. But
believe he did, and it is certain (as Huxley has forcibly pointed out{3}) that
the doctrine of uniformitarianism when applied to Biology leads of
necessity to Evolution. If the extermination of a species is no more
catastrophic than the natural death of an individual, why should the birth of
a species be any more miraculous than the birth of an individual? It is quite
clear that this thought was vividly present to Darwin when he was writing
out his early thoughts in the 1837 Note Book{4}:—
“Propagation explains why modern animals same type as extinct, which
is law almost proved. They die, without they change, like golden pippins; it
is a generation of species like generation of individuals.”
“If species generate other species their race is not utterly cut off.”
These quotations show that he was struggling to see in the origin of
species a process just as scientifically comprehensible as the birth of
individuals. They show, I think, that he recognised the two things not
merely as similar but as identical.
It is impossible to know how soon the ferment of uniformitarianism
began to work, but it is fair to suspect that in 1832 he had already begun to
see that mutability was the logical conclusion of Lyell’s doctrine, though
this was not acknowledged by Lyell himself.

There were however other factors of change. In his Autobiography {5} he
wrote:—“During the voyage of the Beagle I had been deeply impressed by
discovering in the Pampean formation great fossil animals covered with
armour like that on the existing armadillos; secondly, by the manner in
which closely allied animals replace one another in proceeding southward
over the Continent; and thirdly, by the South American character of most of
the productions of the Galapagos archipelago, and more especially by the
manner in which they differ slightly on each island of the group; none of the
islands appearing to be very ancient in a geological sense. It was evident
that such facts as these, as well as many others, could only be explained on
the supposition that species gradually become modified; and the subject
haunted me.”
Again we have to ask: how soon did any of these influences produce an
effect on Darwin’s mind? Different answers have been attempted. Huxley{6}
held that these facts could not have produced their essential effect until the
voyage had come to an end, and the “relations of the existing with the
extinct species and of the species of the different geographical areas with
one another were determined with some exactness.” He does not therefore
allow that any appreciable advance towards evolution was made during the
actual voyage of the Beagle.
Professor Judd{7} takes a very different view. He holds that November
1832 may be given with some confidence as the “date at which Darwin
commenced that long series of observations and reasonings which
eventually culminated in the preparation of the Origin of Species.”
Though I think these words suggest a more direct and continuous march
than really existed between fossil-collecting in 1832 and writing the Origin
of Species in 1859, yet I hold that it was during the voyage that Darwin's
mind began to be turned in the direction of Evolution, and I am therefore in
essential agreement with Prof. Judd, although I lay more stress than he does
on the latter part of the voyage.
Let us for a moment confine our attention to the passage, above quoted,
from the Autobiography and to what is said in the Introduction to the
Origin, Ed. i., viz. “When on board H.M.S. ‘Beagle,’ as naturalist, I was
much struck with certain facts in the distribution of the inhabitants of South

America, and in the geological relations of the present to the past
inhabitants of that continent.” These words, occurring where they do, can
only mean one thing,—namely that the facts suggested an evolutionary
interpretation. And this being so it must be true that his thoughts began to
flow in the direction of Descent at this early date.
I am inclined to think that the “new light which was rising in his
mind{8}” had not yet attained any effective degree of steadiness or
brightness. I think so because in his Pocket Book under the date 1837 he
wrote, “In July opened first note-book on ‘transmutation of species.’ Had
been greatly struck from about month of previous March{9} on character of
South American fossils, and species on Galapagos Archipelago. These facts
origin (especially latter), of all my views.” But he did not visit the
Galapagos till 1835 and I therefore find it hard to believe that his
evolutionary views attained any strength or permanence until at any rate
quite late in the voyage. The Galapagos facts are strongly against Huxley’s
view, for Darwin’s attention was “thoroughly aroused{10}” by comparing the
birds shot by himself and by others on board. The case must have struck
him at once,—without waiting for accurate determinations,—as a
microcosm of evolution.
It is also to be noted, in regard to the remains of extinct animals, that, in
the above quotation from his Pocket Book, he speaks of March 1837 as the
time at which he began to be “greatly struck on character of South
American fossils,” which suggests at least that the impression made in 1832
required reinforcement before a really powerful effect was produced.
We may therefore conclude, I think, that the evolutionary current in my
father's thoughts had continued to increase in force from 1832 onwards,
being especially reinforced at the Galapagos in 1835 and again in 1837
when he was overhauling the results, mental and material, of his travels.
And that when the above record in the Pocket Book was made he
unconsciously minimised the earlier beginnings of his theorisings, and laid
more stress on the recent thoughts which were naturally more vivid to him.
In his letter{11} to Otto Zacharias (1877) he wrote, “On my return home in
the autumn of 1836, I immediately began to prepare my Journal for
publication, and then saw how many facts indicated the common descent of

species.” This again is evidence in favour of the view that the later growths
of his theory were the essentially important parts of its development.
In the same letter to Zacharias he says, “When I was on board the
Beagle I believed in the permanence of species, but as far as I can
remember vague doubts occasionally flitted across my mind.” Unless Prof.
Judd and I are altogether wrong in believing that late or early in the voyage
(it matters little which) a definite approach was made to the evolutionary
standpoint, we must suppose that in 40 years such advance had shrunk in
his recollection to the dimensions of “vague doubts.” The letter to Zacharias
shows I think some forgetting of the past where the author says, “But I did
not become convinced that species were mutable until, I think, two or three
years had elapsed.” It is impossible to reconcile this with the contents of the
evolutionary Note Book of 1837. I have no doubt that in his retrospect he
felt that he had not been “convinced that species were mutable” until he had
gained a clear conception of the mechanism of natural selection, i.e. in
1838-9.
But even on this last date there is some room, not for doubt, but for
surprise. The passage in the Autobiography{12} is quite clear, namely that in
October 1838 he read Malthus’s Essay on the principle of Population and
“being well prepared to appreciate the struggle for existence ..., it at once
struck me that under these circumstances favourable variations would tend
to be preserved, and unfavourable ones to be destroyed. The result of this
would be the formation of new species. Here then I had at last got a theory
by which to work.”
It is surprising that Malthus should have been needed to give him the
clue, when in the Note Book of 1837 there should occur—however
obscurely expressed—the following forecast{13} of the importance of the
survival of the fittest. “With respect to extinction, we can easily see that a
variety of the ostrich (Petise {14}), may not be well adapted, and thus perish
out; or on the other hand, like Orpheus{15}, being favourable, many might be
produced. This requires the principle that the permanent variations
produced by confined breeding and changing circumstances are continued
and produce«d» according to the adaptation of such circumstances, and
therefore that death of species is a consequence (contrary to what would
appear in America) of non-adaptation of circumstances.”

I can hardly doubt, that with his knowledge of the interdependence of
organisms and the tyranny of conditions, his experience would have
crystallized out into “a theory by which to work” even without the aid of
Malthus.
In my father's Autobiography{16} he writes, “In June 1842 I first allowed
myself the satisfaction of writing a very brief abstract of my theory in
pencil in 35 pages; and this was enlarged during the summer of 1844 into
one of 230 pages{17}, which I had fairly copied out and still possess.” These
two Essays, of 1842 and 1844, are now printed under the title The
Foundations of the Origin of Species.
It will be noted that in the above passage he does not mention the ms. of
1842 as being in existence, and when I was at work on Life and Letters I
had not seen it. It only came to light after my mother's death in 1896 when
the house at Down was vacated. The ms. was hidden in a cupboard under
the stairs which was not used for papers of any value, but rather as an
overflow for matter which he did not wish to destroy.
The statement in the Autobiography that the ms. was written in 1842
agrees with an entry in my fathers Diary:—
“1842. May 18th went to Maer. June 15th to Shrewsbury, and on 18th to
Capel Curig.... During my stay at Maer and Shrewsbury (five years after
commencement) wrote pencil sketch of my species theory.” Again in a letter
to Lyell (June 18, 1858) he speaks of his “ms. sketch written out in
1842{18}.” In the Origin of Species, Ed. i. p. 1, he speaks of beginning his
speculations in 1837 and of allowing himself to draw up some “short notes”
after “five years' work,” i.e. in 1842. So far there seems no doubt as to 1842
being the date of the first sketch; but there is evidence in favour of an
earlier date{19}. Thus across the Table of Contents of the bound copy of the
1844 ms. is written in my father's hand “This was sketched in 1839.” Again
in a letter to Mr Wallace{20} (Jan. 25, 1859) he speaks of his own
contributions to the Linnean paper{21} of July 1, 1858, as “written in 1839,
now just twenty years ago.” This statement as it stands is undoubtedly
incorrect, since the extracts are from the ms. of 1844, about the date of
which no doubt exists; but even if it could be supposed to refer to the 1842
Essay, it must, I think, be rejected. I can only account for his mistake by the

supposition that my father had in mind the date (1839) at which the
framework of his theory was laid down. It is worth noting that in his
Autobiography (p. 88) he speaks of the time “about 1839, when the theory
was clearly conceived.” However this may be there can be no doubt that
1842 is the correct date. Since the publication of Life and Letters I have
gained fresh evidence on this head. A small packet containing 13 pp. of ms.
came to light in 1896. On the outside is written “First Pencil Sketch of
Species Theory. Written at Maer and Shrewsbury during May and June
1842.” It is not however written in pencil, and it consists of a single chapter
on The Principles of Variation in Domestic Organisms. A single
unnumbered page is written in pencil, and is headed “Maer, May 1842,
useless”; it also bears the words “This page was thought of as introduction.”
It consists of the briefest sketch of the geological evidence for evolution,
together with words intended as headings for discussion,—such as
“Affinity,—unity of type,—fœtal state,—abortive organs.”
The back of this “useless” page is of some interest, although it does not
bear on the question of date,—the matter immediately before us.
It seems to be an outline of the Essay or sketch of 1842, consisting of
the titles of the three chapters of which it was to have consisted.
“I. The Principles of Var. in domestic organisms.
“II. The possible and probable application of these same principles to
wild animals and consequently the possible and probable production of wild
races, analogous to the domestic ones of plants and animals.
“III. The reasons for and against believing that such races have really
been produced, forming what are called species.”
It will be seen that Chapter III as originally designed corresponds to
Part II (p. 22) of the Essay of 1842, which is (p. 7) defined by the author as
discussing “whether the characters and relations of animated things are such
as favour the idea of wild species being races descended from a common
stock.” Again at p. 23 the author asks “What then is the evidence in favour
of it (the theory of descent) and what the evidence against it.” The
generalised section of his Essay having been originally Chapter III{22}

accounts for the curious error which occurs in pp. 18 and 22 where the
second Part of the Essay is called Part III.
The division of the Essay into two parts is maintained in the enlarged
Essay of 1844, in which he writes: “The Second Part of this work is devoted
to the general consideration of how far the general economy of nature
justifies or opposes the belief that related species and genera are descended
from common stocks.” The Origin of Species however is not so divided.
We may now return to the question of the date of the Essay. I have
found additional evidence in favour of 1842 in a sentence written on the
back of the Table of Contents of the 1844 ms.—not the copied version but
the original in my father's writing: “This was written and enlarged from a
sketch in 37 pages{23} in Pencil (the latter written in summer of 1842 at
Maer and Shrewsbury) in beginning of 1844, and finished it «sic» in July;
and finally corrected the copy by Mr Fletcher in the last week in
September.” On the whole it is impossible to doubt that 1842 is the date of
the earlier of the two Essays.
The sketch of 1842 is written on bad paper with a soft pencil, and is in
many parts extremely difficult to read, many of the words ending in mere
scrawls and being illegible without context. It is evidently written rapidly,
and is in his most elliptical style, the articles being frequently omitted, and
the sentences being loosely composed and often illogical in structure. There
is much erasure and correction, apparently made at the moment of writing,
and the ms. does not give the impression of having been re-read with any
care. The whole is more like hasty memoranda of what was clear to himself,
than material for the convincing of others.
Many of the pages are covered with writing on the back, an instance of
his parsimony in the matter of paper{24}. This matter consists partly of
passages marked for insertion in the text, and these can generally (though
by no means always) be placed where he intended. But he also used the
back of one page for a preliminary sketch to be rewritten on a clean sheet.
These parts of the work have been printed as footnotes, so as to allow what
was written on the front of the pages to form a continuous text. A certain
amount of repetition is unavoidable, but much of what is written on the
backs of the pages is of too much interest to be omitted. Some of the matter

here given in footnotes may, moreover, have been intended as the final text
and not as the preliminary sketch.
When a word cannot be deciphered, it is replaced by:—«illegible», the
angular brackets being, as already explained, a symbol for an insertion by
the editor. More commonly, however, the context makes the interpretation
of a word reasonably sure although the word is not strictly legible. Such
words are followed by an inserted mark of interrogation «?». Lastly, words
inserted by the editor, of which the appropriateness is doubtful, are printed
thus «variation?».
Two kinds of erasure occur in the ms. of 1842. One by vertical lines
which seem to have been made when the 35 pp. ms. was being expanded
into that of 1844, and merely imply that such a page is done with: and
secondly the ordinary erasures by horizontal lines. I have not been quite
consistent in regard to these: I began with the intention of printing (in
square brackets) all such erasures. But I ultimately found that the confusion
introduced into the already obscure sentences was greater than any possible
gain; and many such erasures are altogether omitted. In the same way I
have occasionally omitted hopelessly obscure and incomprehensible
fragments, which if printed would only have burthened the text with a string
of «illegible»s and queried words. Nor have I printed the whole of what is
written on the backs of the pages, where it seemed to me that nothing but
unnecessary repetition would have been the result.
In the matter of punctuation I have given myself a free hand. I may no
doubt have misinterpreted the author's meaning in so doing, but without
such punctuation, the number of repellantly crabbed sentences would have
been even greater than at present. In dealing with the Essay of 1844, I have
corrected some obvious slips without indicating such alterations, because
the ms. being legible, there is no danger of changing the author's meaning.
The sections into which the Essay of 1842 is divided are in the original
merely indicated by a gap in the ms. or by a line drawn across the page. No
titles are given except in the case of § viii.; and § ii. is the only section
which has a number in the original. I might equally well have made sections
of what are now subsections, e.g. Natural Selection p. 7, or Extermination
p. 28. But since the present sketch is the germ of the Essay of 1844, it

seemed best to preserve the identity between the two works, by using such
of the author's divisions as correspond to the chapters of the enlarged
version of 1844. The geological discussion with which Part II begins
corresponds to two chapters (IV and V) of the 1844 Essay. I have therefore
described it as §§ iv. and v., although I cannot make sure of its having
originally consisted of two sections. With this exception the ten sections of
the Essay of 1842 correspond to the ten chapters of that of 1844.
The Origin of Species differs from the sketch of 1842 in not being
divided into two parts. But the two volumes resemble each other in general
structure. Both begin with a statement of what may be called the
mechanism of evolution,—variation and selection: in both the argument
proceeds from the study of domestic organisms to that of animals and plants
in a state of nature. This is followed in both by a discussion of the
Difficulties on Theory and this by a section Instinct which in both cases is
treated as a special case of difficulty.
If I had to divide the Origin (first edition) into two parts without any
knowledge of earlier ms., I should, I think, make Part II begin with Ch. VI,
Difficulties on Theory. A possible reason why this part of the argument is
given in Part I of the Essay of 1842 may be found in the Essay of 1844,
where it is clear that the chapter on instinct is placed in Part I because the
author thought it of importance to show that heredity and variation occur in
mental attributes. The whole question is perhaps an instance of the sort of
difficulty which made the author give up the division of his argument into
two Parts when he wrote the Origin. As matters stand §§ iv. and v. of the
1842 Essay correspond to the geological chapters, IX and X, in the Origin.
From this point onwards the material is grouped in the same order in both
works: geographical distribution; affinities and classification; unity of type
and morphology; abortive or rudimentary organs; recapitulation and
conclusion.
In enlarging the Essay of 1842 into that of 1844, the author retained the
sections of the sketch as chapters in the completer presentment. It follows
that what has been said of the relation of the earlier Essay to the Origin is
generally true of the 1844 Essay. In the latter, however, the geological
discussion is, clearly instead of obscurely, divided into two chapters, which
correspond roughly with Chapters IX and X of the Origin. But part of the

contents of Chapter X (Origin) occurs in Chapter VI (1844) on
Geographical Distribution. The treatment of distribution is particularly full
and interesting in the 1844 Essay, but the arrangement of the material,
especially the introduction of § iii. p. 183, leads to some repetition which is
avoided in the Origin. It should be noted that Hybridism, which has a
separate chapter (VIII) in the Origin, is treated in Chapter II of the Essay.
Finally that Chapter XIII (Origin) corresponds to Chapters VII, VIII and IX
of the work of 1844.
The fact that in 1842, seventeen years before the publication of the
Origin, my father should have been able to write out so full an outline of his
future work, is very remarkable. In his Autobiography{25} he writes of the
1844 Essay, “But at that time I overlooked one problem of great
importance.... This problem is the tendency in organic beings descended
from the same stock to diverge in character as they become modified.” The
absence of the principle of divergence is of course also a characteristic of
the sketch of 1842. But at p. 37, the author is not far from this point of view.
The passage referred to is: “If any species, A, in changing gets an advantage
and that advantage ... is inherited, A will be the progenitor of several genera
or even families in the hard struggle of nature. A will go on beating out
other forms, it might come that A would people «the» earth,—we may now
not have one descendant on our globe of the one or several original
creations{26}.” But if the descendants of A have peopled the earth by beating
out other forms, they must have diverged in occupying the innumerable
diverse modes of life from which they expelled their predecessors. What I
wrote{27} on this subject in 1887 is I think true: “Descent with modification
implies divergence, and we become so habituated to a belief in descent, and
therefore in divergence, that we do not notice the absence of proof that
divergence is in itself an advantage.”
The fact that there is no set discussion on the principle of divergence in
the 1844 Essay, makes it clear why the joint paper read before the Linnean
Society on July 1, 1858, included a letter{28} to Asa Gray, as well as an
extract{29} from the Essay of 1844. It is clearly because the letter to Gray
includes a discussion on divergence, and was thus, probably, the only
document, including this subject, which could be appropriately made use of.
It shows once more how great was the importance attached by its author to
the principle of divergence.

I have spoken of the hurried and condensed manner in which the sketch
of 1842 is written; the style of the later Essay (1844) is more finished. It
has, however, the air of an uncorrected ms. rather than of a book which has
gone through the ordeal of proof sheets. It has not all the force and
conciseness of the Origin, but it has a certain freshness which gives it a
character of its own. It must be remembered that the Origin was an abstract
or condensation of a much bigger book, whereas the Essay of 1844 was an
expansion of the sketch of 1842. It is not therefore surprising that in the
Origin there is occasionally evident a chafing against the author's self-
imposed limitation. Whereas in the 1844 Essay there is an air of freedom, as
if the author were letting himself go, rather than applying the curb. This
quality of freshness and the fact that some questions were more fully
discussed in 1844 than in 1859, makes the earlier work good reading even
to those who are familiar with the Origin.
The writing of this Essay “during the summer of 1844,” as stated in the
Autobiography{30}, and “from memory,” as Darwin says elsewhere{31}, was a
remarkable achievement, and possibly renders more conceivable the still
greater feat of the writing of the Origin between July 1858 and September
1859.
It is an interesting subject for speculation: what influence on the world
the Essay of 1844 would have exercised, had it been published in place of
the Origin. The author evidently thought of its publication in its present
state as an undesirable expedient, as appears clearly from the following
extracts from the Life and Letters, vol. ii. pp. 16—18:

C. Darwin to Mrs Darwin.
Down, July 5, 1844.
“... I have just finished my sketch of my species theory. If, as I believe,
my theory in time be accepted even by one competent judge, it will be a
considerable step in science.
“I therefore write this in case of my sudden death, as my most solemn
and last request, which I am sure you will consider the same as if legally
entered in my will, that you will devote £400 to its publication, and further

will yourself, or through Hensleigh{32}, take trouble in promoting it. I wish
that my sketch be given to some competent person, with this sum to induce
him to take trouble in its improvement and enlargement. I give to him all
my books on Natural History, which are either scored or have references at
the end to the pages, begging him carefully to look over and consider such
passages as actually bearing, or by possibility bearing, on this subject. I
wish you to make a list of all such books as some temptation to an editor. I
also request that you will hand over «to» him all those scraps roughly
divided into eight or ten brown paper portfolios. The scraps, with copied
quotations from various works, are those which may aid my editor. I also
request that you, or some amanuensis, will aid in deciphering any of the
scraps which the editor may think possibly of use. I leave to the editor's
judgment whether to interpolate these facts in the text, or as notes, or under
appendices. As the looking over the references and scraps will be a long
labour, and as the correcting and enlarging and altering my sketch will also
take considerable time, I leave this sum of £400 as some remuneration, and
any profits from the work. I consider that for this the editor is bound to get
the sketch published either at a publisher's or his own risk. Many of the
scraps in the portfolios contain mere rude suggestions and early views, now
useless, and many of the facts will probably turn out as having no bearing
on my theory.
“With respect to editors, Mr Lyell would be the best if he would
undertake it; I believe he would find the work pleasant, and he would learn
some facts new to him. As the editor must be a geologist as well as a
naturalist, the next best editor would be Professor Forbes of London. The
next best (and quite best in many respects) would be Professor Henslow. Dr
Hooker would be very good. The next, Mr Strickland{33}. If none of these
would undertake it, I would request you to consult with Mr Lyell, or some
other capable man, for some editor, a geologist and naturalist. Should one
other hundred pounds make the difference of procuring a good editor, I
request earnestly that you will raise £500.
“My remaining collections in Natural History may be given to any one
or any museum where «they» would be accepted....”
«The following note seems to have formed part of the original letter, but
may have been of later date:»

“Lyell, especially with the aid of Hooker (and of any good zoological
aid), would be best of all. Without an editor will pledge himself to give up
time to it, it would be of no use paying such a sum.
“If there should be any difficulty in getting an editor who would go
thoroughly into the subject, and think of the bearing of the passages marked
in the books and copied out of scraps of paper, then let my sketch be
published as it is, stating that it was done several years ago{34}, and from
memory without consulting any works, and with no intention of publication
in its present form.”
The idea that the sketch of 1844 might remain, in the event of his death,
as the only record of his work, seems to have been long in his mind, for in
August, 1854, when he had finished with the Cirripedes, and was thinking
of beginning his “species work,” he added on the back of the above letter,
“Hooker by far best man to edit my species volume. August 1854.”
I have called attention in footnotes to many points in which the Origin
agrees with the Foundations. One of the most interesting is the final
sentence, practically the same in the Essays of 1842 and 1844, and almost
identical with the concluding words of the Origin. I have elsewhere pointed
out{35} that the ancestry of this eloquent passage may be traced one stage
further back,—to the Note Book of 1837. I have given this sentence as an
appropriate motto for the Foundations in its character of a study of general
laws. It will be remembered that a corresponding motto from Whewell's
Bridgewater Treatise is printed opposite the title-page of the Origin of
Species.
Mr Huxley who, about the year 1887, read the Essay of 1844, remarked
that “much more weight is attached to the influence of external conditions
in producing variation and to the inheritance of acquired habits than in the
Origin.” In the Foundations the effect of conditions is frequently
mentioned, and Darwin seems to have had constantly in mind the need of
referring each variation to a cause. But I gain the impression that the
slighter prominence given to this view in the Origin was not due to change
of opinion, but rather because he had gradually come to take this view for
granted; so that in the scheme of that book, it was overshadowed by
considerations which then seemed to him more pressing. With regard to the

inheritance of acquired characters I am not inclined to agree with Huxley. It
is certain that the Foundations contains strong recognition of the
importance of germinal variation, that is of external conditions acting
indirectly through the “reproductive functions.” He evidently considered
this as more important than the inheritance of habit or other acquired
peculiarities.
Another point of interest is the weight he attached in 1842-4 to “sports”
or what are now called “mutations.” This is I think more prominent in the
Foundations than in the first edition of the Origin, and certainly than in the
fifth and sixth editions.
Among other interesting points may be mentioned the “good effects of
crossing” being “possibly analogous to good effects of change in
condition,”—a principle which he upheld on experimental grounds in his
Cross and Self-Fertilisation in 1876.
In conclusion, I desire to express my thanks to Mr Wallace for a
footnote he was good enough to supply: and to Professor Bateson, Sir W.
Thiselton-Dyer, Dr Gadow, Professor Judd, Dr Marr, Col. Prain and Dr
Stapf for information on various points. I am also indebted to Mr
Rutherford, of the University Library, for his careful copy of the manuscript
of 1842.
Cambridge,
June 9, 1909.

EXPLANATION OF SIGNS, &c.
[ ] Means that the words so enclosed are erased in the original ms.
« » Indicates an insertion by the Editor.
Origin, Ed. vi. refers to the Popular Edition.

PART I.
§ I. «On Variation under Domestication, and on the
Principles of Selection.»
An individual organism placed under new conditions [often] sometimes
varies in a small degree and in very trifling respects such as stature, fatness,
sometimes colour, health, habits in animals and probably disposition. Also
habits of life develope certain parts. Disuse atrophies. [Most of these slight
variations tend to become hereditary.]
When the individual is multiplied for long periods by buds the variation
is yet small, though greater and occasionally a single bud or individual
departs widely from its type (example){36} and continues steadily to
propagate, by buds, such new kind.
When the organism is bred for several generations under new or varying
conditions, the variation is greater in amount and endless in kind
[especially{37} holds good when individuals have long been exposed to new
conditions]. The nature of the external conditions tends to effect some
definite change in all or greater part of offspring,—little food, small size—
certain foods harmless &c. &c. organs affected and diseases—extent
unknown. A certain degree of variation (Müller's twins){38} seems inevitable
effect of process of reproduction. But more important is that simple «?»
generation, especially under new conditions [when no crossing] «causes»
infinite variation and not direct effect of external conditions, but only in as
much as it affects the reproductive functions{39}. There seems to be no part
(beau ideal of liver){40} of body, internal or external, or mind or habits, or
instincts which does not vary in some small degree and [often] some «?» to
a great amount.
[All such] variations [being congenital] or those very slowly acquired of
all kinds [decidedly evince a tendency to become hereditary], when not so
become simple variety, when it does a race. Each{41} parent transmits its
peculiarities, therefore if varieties allowed freely to cross, except by the

chance of two characterized by same peculiarity happening to marry, such
varieties will be constantly demolished{42}. All bisexual animals must cross,
hermaphrodite plants do cross, it seems very possible that hermaphrodite
animals do cross,—conclusion strengthened: ill effects of breeding in and
in, good effects of crossing possibly analogous to good effects of change in
condition «?»{43}.
Therefore if in any country or district all animals of one species be
allowed freely to cross, any small tendency in them to vary will be
constantly counteracted. Secondly reversion to parent form—analogue of
vis medicatrix{44}. But if man selects, then new races rapidly formed,—of
late years systematically followed,—in most ancient times often practically
followed{45}. By such selection make race-horse, dray-horse—one cow good
for tallow, another for eating &c.—one plant's good lay «illegible» in leaves
another in fruit &c. &c.: the same plant to supply his wants at different
times of year. By former means animals become adapted, as a direct effect
to a cause, to external conditions, as size of body to amount of food. By this
latter means they may also be so adapted, but further they may be adapted
to ends and pursuits, which by no possibility can affect growth, as existence
of tallow-chandler cannot tend to make fat. In such selected races, if not
removed to new conditions, and «if» preserved from all cross, after several
generations become very true, like each other and not varying. But man{46}
selects only «?» what is useful and curious—has bad judgment, is
capricious,—grudges to destroy those that do not come up to his pattern,—
has no [knowledge] power of selecting according to internal variations,—
can hardly keep his conditions uniform,—[cannot] does not select those
best adapted to the conditions under which «the» form «?» lives, but those
most useful to him. This might all be otherwise.

§ II. «On Variation in a State of Nature and on the Natural
Means of Selection.»
Let us see how far above principles of variation apply to wild animals.
Wild animals vary exceedingly little—yet they are known as individuals{47}.
British Plants, in many genera number quite uncertain of varieties and
species: in shells chiefly external conditions{48}. Primrose and cowslip. Wild
animals from different [countries can be recognized]. Specific character
gives some organs as varying. Variations analogous in kind, but less in

degree with domesticated animals—chiefly external and less important
parts.
Our experience would lead us to expect that any and every one of these
organisms would vary if «the organism were» taken away «?» and placed
under new conditions. Geology proclaims a constant round of change,
bringing into play, by every possible «?» change of climate and the death of
pre-existing inhabitants, endless variations of new conditions. These «?»
generally very slow, doubtful though «illegible» how far the slowness «?»
would produce tendency to vary. But Geolog«ists» show change in
configuration which, together with the accidents of air and water and the
means of transportal which every being possesses, must occasionally bring,
rather suddenly, organism to new conditions and «?» expose it for several
generations. Hence «?» we should expect every now and then a wild form
to vary{49}; possibly this may be cause of some species varying more than
others.
According to nature of new conditions, so we might expect all or
majority of organisms born under them to vary in some definite way.
Further we might expect that the mould in which they are cast would
likewise vary in some small degree. But is there any means of selecting
those offspring which vary in the same manner, crossing them and keeping
their offspring separate and thus producing selected races: otherwise as the
wild animals freely cross, so must such small heterogeneous varieties be
constantly counter-balanced and lost, and a uniformity of character [kept
up] preserved. The former variation as the direct and necessary effects of
causes, which we can see can act on them, as size of body from amount of
food, effect of certain kinds of food on certain parts of bodies &c. &c.; such
new varieties may then become adapted to those external [natural] agencies
which act on them. But can varieties be produced adapted to end, which
cannot possibly influence their structure and which it is absurd to look «at»
as effects of chance. Can varieties like some vars of domesticated animals,
like almost all wild species be produced adapted by exquisite means to prey
on one animal or to escape from another,—or rather, as it puts out of
question effects of intelligence and habits, can a plant become adapted to
animals, as a plant which cannot be impregnated without agency of insect;
or hooked seeds depending on animal“s existence: woolly animals cannot
have any direct effect on seeds of plant. This point which all theories about

climate adapting woodpecker{50} to crawl «?» up trees, «illegible» miseltoe,
«sentence incomplete». But if every part of a plant or animal was to vary
«illegible», and if a being infinitely more sagacious than man (not an
omniscient creator) during thousands and thousands of years were to select
all the variations which tended towards certain ends ([or were to produce
causes «?» which tended to the same end]), for instance, if he foresaw a
canine animal would be better off, owing to the country producing more
hares, if he were longer legged and keener sight,—greyhound produced{51}.
If he saw that aquatic «animal would need» skinned toes. If for some
unknown cause he found it would advantage a plant, which «?» like most
plants is occasionally visited by bees &c.: if that plant’s seed were
occasionally eaten by birds and were then carried on to rotten trees, he
might select trees with fruit more agreeable to such birds as perched, to
ensure their being carried to trees; if he perceived those birds more often
dropped the seeds, he might well have selected a bird who would
«illegible» rotten trees or [gradually select plants which «he» had proved to
live on less and less rotten trees]. Who, seeing how plants vary in garden,
what blind foolish man has done{52} in a few years, will deny an all-seeing
being in thousands of years could effect (if the Creator chose to do so),
either by his own direct foresight or by intermediate means,—which will
represent «?» the creator of this universe. Seems usual means. Be it
remembered I have nothing to say about life and mind and all forms
descending from one common type{53}. I speak of the variation of the
existing great divisions of the organised kingdom, how far I would go,
hereafter to be seen.
Before considering whether «there» be any natural means of selection,
and secondly (which forms the 2nd Part of this sketch) the far more
important point whether the characters and relations of animated «things»
are such as favour the idea of wild species being races «?» descended from
a common stock, as the varieties of potato or dahlia or cattle having so
descended, let us consider probable character of [selected races] wild
varieties.
Natural Selection. De Candolle’s war of nature,—seeing contented face
of nature,—may be well at first doubted; we see it on borders of perpetual
cold{54}. But considering the enormous geometrical power of increase in
every organism and as «?» every country, in ordinary cases «countries»

must be stocked to full extent, reflection will show that this is the case.
Malthus on man,—in animals no moral [check] restraint «?»—they breed in
time of year when provision most abundant, or season most favourable,
every country has its seasons,—calculate robins,—oscillating from years of
destruction{55}. If proof were wanted let any singular change of climate
«occur» here «?», how astoundingly some tribes «?» increase, also
introduced animals{56}, the pressure is always ready,—capacity of alpine
plants to endure other climates,—think of endless seeds scattered abroad,—
forests regaining their percentage{57},—a thousand wedges{58} are being
forced into the œconomy of nature. This requires much reflection; study
Malthus and calculate rates of increase and remember the resistance,—only
periodical.
The unavoidable effect of this «is» that many of every species are
destroyed either in egg or [young or mature (the former state the more
common)]. In the course of a thousand generations infinitesimally small
differences must inevitably tell{59}; when unusually cold winter, or hot or
dry summer comes, then out of the whole body of individuals of any
species, if there be the smallest differences in their structure, habits,
instincts [senses], health &c., «it» will on an average tell; as conditions
change a rather larger proportion will be preserved: so if the chief check to
increase falls on seeds or eggs, so will, in the course of 1000 generations or
ten thousand, those seeds (like one with down to fly{60}) which fly furthest
and get scattered most ultimately rear most plants, and such small
differences tend to be hereditary like shades of expression in human
countenance. So if one parent «?» fish deposits its egg in infinitesimally
different circumstances, as in rather shallower or deeper water &c., it will
then «?» tell.
Let hares{61} increase very slowly from change of climate affecting
peculiar plants, and some other «illegible» rabbit decrease in same
proportion [let this unsettle organisation of], a canine animal, who formerly
derived its chief sustenance by springing on rabbits or running them by
scent, must decrease too and might thus readily become exterminated. But
if its form varied very slightly, the long legged fleet ones, during a thousand
years being selected, and the less fleet rigidly destroyed must, if no law of
nature be opposed to it, alter forms.

Remember how soon Bakewell on the same principle altered cattle and
Western, sheep,—carefully avoiding a cross (pigeons) with any breed. We
cannot suppose that one plant tends to vary in fruit and another in flower,
and another in flower and foliage,—some have been selected for both fruit
and flower: that one animal varies in its covering and another not,—another
in its milk. Take any organism and ask what is it useful for and on that point
it will be found to vary,—cabbages in their leaf,—corn in size «and» quality
of grain, both in times of year,—kidney beans for young pod and cotton for
envelope of seeds &c. &c.: dogs in intellect, courage, fleetness and smell
«?»: pigeons in peculiarities approaching to monsters. This requires
consideration,—should be introduced in first chapter if it holds, I believe it
does. It is hypothetical at best{62}.
Nature’s variation far less, but such selection far more rigid and
scrutinising. Man’s races not [even so well] only not better adapted to
conditions than other races, but often not «?» one race adapted to its
conditions, as man keeps and propagates some alpine plants in garden.
Nature lets «an» animal live, till on actual proof it is found less able to do
the required work to serve the desired end, man judges solely by his eye,
and knows not whether nerves, muscles, arteries, are developed in
proportion to the change of external form.
Besides selection by death, in bisexual animals «illegible» the selection
in time of fullest vigour, namely struggle of males; even in animals which
pair there seems a surplus «?» and a battle, possibly as in man more males
produced than females, struggle of war or charms{63}. Hence that male
which at that time is in fullest vigour, or best armed with arms or ornaments
of its species, will gain in hundreds of generations some small advantage
and transmit such characters to its offspring. So in female rearing its young,
the most vigorous and skilful and industrious, «whose» instincts «are» best
developed, will rear more young, probably possessing her good qualities,
and a greater number will thus «be» prepared for the struggle of nature.
Compared to man using a male alone of good breed. This latter section only
of limited application, applies to variation of [specific] sexual characters.
Introduce here contrast with Lamarck,—absurdity of habit, or chance?? or
external conditions, making a woodpecker adapted to tree{64}.

Before considering difficulties of theory of selection let us consider
character of the races produced, as now explained, by nature. Conditions
have varied slowly and the organisms best adapted in their whole course of
life to the changed conditions have always been selected,—man selects
small dog and afterwards gives it profusion of food,—selects a long-backed
and short-legged breed and gives it no particular exercise to suit this
function &c. &c. In ordinary cases nature has not allowed her race to be
contaminated with a cross of another race, and agriculturists know how
difficult they find always to prevent this,—effect would be trueness. This
character and sterility when crossed, and generally a greater amount of
difference, are two main features, which distinguish domestic races from
species.
[Sterility not universal admitted by all{65}. Gladiolus, Crinum,
Calceolaria{66} must be species if there be such a thing. Races of dogs and
oxen: but certainly very general; indeed a gradation of sterility most
perfect{67} very general. Some nearest species will not cross (crocus, some
heath «?»), some genera cross readily (fowls{68} and grouse, peacock &c.).
Hybrids no ways monstrous quite perfect except secretions{69} hence even
the mule has bred,—character of sterility, especially a few years ago «?»
thought very much more universal than it now is, has been thought the
distinguishing character; indeed it is obvious if all forms freely crossed,
nature would be a chaos. But the very gradation of the character, even if it
always existed in some degree which it does not, renders it impossible as
marks «?» those «?» suppose distinct as species{70}]. Will analogy throw any
light on the fact of the supposed races of nature being sterile, though none
of the domestic ones are? Mr Herbert «and» Koelreuter have shown
external differences will not guide one in knowing whether hybrids will be
fertile or not, but the chief circumstance is constitutional differences{71},
such as being adapted to different climate or soil, differences which [must]
probably affect the whole body of the organism and not any one part. Now
wild animals, taken out of their natural conditions, seldom breed. I do not
refer to shows or to Zoological Societies where many animals unite, but «do
not?» breed, and others will never unite, but to wild animals caught and
kept quite tame left loose and well fed about houses and living many years.
Hybrids produced almost as readily as pure breds. St Hilaire great
distinction of tame and domestic,—elephants,—ferrets{72}. Reproductive

organs not subject to disease in Zoological Garden. Dissection and
microscope show that hybrid is in exactly same condition as another animal
in the intervals of breeding season, or those animals which taken wild and
not bred in domesticity, remain without breeding their whole lives. It should
be observed that so far from domesticity being unfavourable in itself «it»
makes more fertile: [when animal is domesticated and breeds, productive
power increased from more food and selection of fertile races]. As far as
animals go might be thought «an» effect on their mind and a special case.
But turning to plants we find same class of facts. I do not refer to seeds
not ripening, perhaps the commonest cause, but to plants not setting, which
either is owing to some imperfection of ovule or pollen. Lindley says
sterility is the [curse] bane of all propagators,—Linnæus about alpine
plants. American bog plants,—pollen in exactly same state as in hybrids,—
same in geraniums. Persian and Chinese{73} lilac will not seed in Italy and
England. Probably double plants and all fruits owe their developed parts
primarily «?» to sterility and extra food thus «?» applied{74}. There is here
gradation «in» sterility and then parts, like diseases, are transmitted
hereditarily. We cannot assign any cause why the Pontic Azalea produces
plenty of pollen and not American{75}, why common lilac seeds and not
Persian, we see no difference in healthiness. We know not on what
circumstances these facts depend, why ferret breeds, and cheetah{76},
elephant and pig in India will not.
Now in crossing it is certain every peculiarity in form and constitution
is transmitted: an alpine plant transmits its alpine tendency to its offspring,
an American plant its American-bog constitution, and «with» animals, those
peculiarities, on which{77} when placed out of their natural conditions they
are incapable of breeding; and moreover they transmit every part of their
constitution, their respiration, their pulse, their instinct, which are all
suddenly modified, can it be wondered at that they are incapable of
breeding? I think it may be truly said it would be more wonderful if they
did. But it may be asked why have not the recognised varieties, supposed to
have been produced through the means of man, [not refused to breed] have
all bred{78}. Variation depends on change of condition and selection{79}, as
far as man’s systematic or unsystematic selection «has» gone; he takes
external form, has little power from ignorance over internal invisible
constitutional differences. Races which have long been domesticated, and

have much varied, are precisely those which were capable of bearing great
changes, whose constitutions were adapted to a diversity of climates.
Nature changes slowly and by degrees. According to many authors probably
breeds of dogs are another case of modified species freely crossing. There is
no variety which «illegible» has been «illegible» adapted to peculiar soil or
situation for a thousand years and another rigorously adapted to another, till
such can be produced, the question is not tried{80}. Man in past ages, could
transport into different climates, animals and plants which would freely
propagate in such new climates. Nature could effect, with selection, such
changes slowly, so that precisely those animals which are adapted to submit
to great changes have given rise to diverse races,—and indeed great doubt
on this head{81}.
Before leaving this subject well to observe that it was shown that a
certain amount of variation is consequent on mere act of reproduction, both
by buds and sexually,—is vastly increased when parents exposed for some
generations to new conditions{82}, and we now find that many animals when
exposed for first time to very new conditions, are «as» incapable of
breeding as hybrids. It [probably] bears also on supposed fact of crossed
animals when not infertile, as in mongrels, tending to vary much, as
likewise seems to be the case, when true hybrids possess just sufficient
fertility to propagate with the parent breeds and inter se for some
generations. This is Koelreuter’s belief. These facts throw light on each
other and support the truth of each other, we see throughout a connection
between the reproductive faculties and exposure to changed conditions of
life whether by crossing or exposure of the individuals{83}.
Difficulties on theory of selection{84}. It may be objected such perfect
organs as eye and ear, could never be formed, in latter less difficulty as
gradations more perfect; at first appears monstrous and to «the» end appears
difficulty. But think of gradation, even now manifest, (Tibia and Fibula).
Everyone will allow if every fossil preserved, gradation infinitely more
perfect; for possibility of selection a perfect «?» gradation is required.
Different groups of structure, slight gradation in each group,—every
analogy renders it probable that intermediate forms have existed. Be it
remembered what strange metamorphoses; part of eye, not directly
connected with vision, might come to be [thus used] gradually worked in
for this end,—swimming bladder by gradation of structure is admitted to

belong to the ear system,—rattlesnake. [Woodpecker best adapted to climb.]
In some cases gradation not possible,—as vertebræ,—actually vary in
domestic animals,—less difficult if growth followed. Looking to whole
animals, a bat formed not for flight{85}. Suppose we had flying fish{86} and
not one of our now called flying fish preserved, who would have guessed
intermediate habits. Woodpeckers and tree-frogs both live in countries
where no trees{87}.
The gradations by which each individual organ has arrived at its present
state, and each individual animal with its aggregate of organs has arrived,
probably never could be known, and all present great difficulties. I merely
wish to show that the proposition is not so monstrous as it at first appears,
and that if good reason can be advanced for believing the species have
descended from common parents, the difficulty of imagining intermediate
forms of structure not sufficient to make one at once reject the theory.

§ III. «On Variation in instincts and other mental
attributes.»

The mental powers of different animals in wild and tame state [present
still greater difficulties] require a separate section. Be it remembered I have
nothing to do with origin of memory, attention, and the different faculties of
the mind{88}, but merely with their differences in each of the great divisions
of nature. Disposition, courage, pertinacity «?», suspicion, restlessness, ill-
temper, sagacity and «the» reverse unquestionably vary in animals and are
inherited (Cuba wildness dogs, rabbits, fear against particular object as man
Galapagos{89}). Habits purely corporeal, breeding season &c., time of going
to rest &c., vary and are hereditary, like the analogous habits of plants
which vary and are inherited. Habits of body, as manner of movement do.
and do. Habits, as pointing and setting on certain occasions do. Taste for
hunting certain objects and manner of doing so,—sheep-dog. These are
shown clearly by crossing and their analogy with true instinct thus shown,
—retriever. Do not know objects for which they do it. Lord Brougham’s
definition{90}. Origin partly habit, but the amount necessarily unknown,
partly selection. Young pointers pointing stones and sheep—tumbling
pigeons—sheep{91} going back to place where born. Instinct aided by
reason, as in the taylor-bird{92}. Taught by parents, cows choosing food,
birds singing. Instincts vary in wild state (birds get wilder) often lost{93};

more perfect,—nest without roof. These facts [only clear way] show how
incomprehensibly brain has power of transmitting intellectual operations.
Faculties{94} distinct from true instincts,—finding [way]. It must I think
be admitted that habits whether congenital or acquired by practice
[sometimes] often become inherited{95}; instincts, influence, equally with
structure, the preservation of animals; therefore selection must, with
changing conditions tend to modify the inherited habits of animals. If this
be admitted it will be found possible that many of the strangest instincts
may be thus acquired. I may observe, without attempting definition, that an
inherited habit or trick (trick because may be born) fulfils closely what we
mean by instinct. A habit is often performed unconsciously, the strangest
habits become associated, do. tricks, going in certain spots &c. &c., even
against will, is excited by external agencies, and looks not to the end,—a
person playing a pianoforte. If such a habit were transmitted it would make
a marvellous instinct. Let us consider some of the most difficult cases of
instincts, whether they could be possibly acquired. I do not say probably,
for that belongs to our 3rd Part{96}, I beg this may be remembered, nor do I
mean to attempt to show exact method. I want only to show that whole
theory ought not at once to be rejected on this score.
Every instinct must, by my theory, have been acquired gradually by
slight changes «illegible» of former instinct, each change being useful to its
then species. Shamming death struck me at first as remarkable objection. I
found none really sham death{97}, and that there is gradation; now no one
doubts that those insects which do it either more or less, do it for some
good, if then any species was led to do it more, and then «?» escaped &c.
&c.
Take migratory instincts, faculty distinct from instinct, animals have
notion of time,—like savages. Ordinary finding way by memory, but how
does savage find way across country,—as incomprehensible to us, as animal
to them,—geological changes,—fishes in river,—case of sheep in Spain{98}.
Architectural instincts,—a manufacturer’s employee in making single
articles extraordinary skill,—often said seem to make it almost «illegible»,
child born with such a notion of playing{99},—we can fancy tailoring
acquired in same perfection,—mixture of reason,—water-ouzel,—taylor-
bird,—gradation of simple nest to most complicated.

Bees again, distinction of faculty,—how they make a hexagon,—
Waterhouse’s theory{100},—the impulse to use whatever faculty they possess,
—the taylor-bird has the faculty of sewing with beak, instinct impels him to
do it.
Last case of parent feeding young with different food (take case of
Galapagos birds, gradation from Hawfinch to Sylvia) selection and habit
might lead old birds to vary taste «?» and form, leaving their instinct of
feeding their young with same food{101},—or I see no difficulty in parents
being forced or induced to vary the food brought, and selection adapting the
young ones to it, and thus by degree any amount of diversity might be
arrived at. Although we can never hope to see the course revealed by which
different instincts have been acquired, for we have only present animals
(not well known) to judge of the course of gradation, yet once grant the
principle of habits, whether congenital or acquired by experience, being
inherited and I can see no limit to the [amount of variation]
extraordinariness «?» of the habits thus acquired.
Summing up this Division. If variation be admitted to occur occasionally
in some wild animals, and how can we doubt it, when we see [all]
thousands «of» organisms, for whatever use taken by man, do vary. If we
admit such variations tend to be hereditary, and how can we doubt it when
we «remember» resemblances of features and character,—disease and
monstrosities inherited and endless races produced (1200 cabbages). If we
admit selection is steadily at work, and who will doubt it, when he
considers amount of food on an average fixed and reproductive powers act
in geometrical ratio. If we admit that external conditions vary, as all
geology proclaims, they have done and are now doing,—then, if no law of
nature be opposed, there must occasionally be formed races, [slightly]
differing from the parent races. So then any such law{102}, none is known,
but in all works it is assumed, in «?» flat contradiction to all known facts,
that the amount of possible variation is soon acquired. Are not all the most
varied species, the oldest domesticated: who «would» think that horses or
corn could be produced? Take dahlia and potato, who will pretend in 5000
years{103} «that great changes might not be effected»: perfectly adapted to
conditions and then again brought into varying conditions. Think what has
been done in few last years, look at pigeons, and cattle. With the amount of
food man can produce he may have arrived at limit of fatness or size, or

thickness of wool «?», but these are the most trivial points, but even in
these I conclude it is impossible to say we know the limit of variation. And
therefore with the [adapting] selecting power of nature, infinitely wise
compared to those of man, «I conclude» that it is impossible to say we
know the limit of races, which would be true «to their» kind; if of different
constitutions would probably be infertile one with another, and which might
be adapted in the most singular and admirable manner, according to their
wants, to external nature and to other surrounding organisms,—such races
would be species. But is there any evidence «that» species «have» been thus
produced, this is a question wholly independent of all previous points, and
which on examination of the kingdom of nature «we» ought to answer one
way or another.

PART II{104}.
§§ IV. & V. «On the evidence from Geology.»
I may premise, that according to the view ordinarily received, the
myriads of organisms peopling this world have been created by so many
distinct acts of creation. As we know nothing of the «illegible» will of a
Creator,—we can see no reason why there should exist any relation between
the organisms thus created; or again, they might be created according to any
scheme. But it would be marvellous if this scheme should be the same as
would result from the descent of groups of organisms from [certain] the
same parents, according to the circumstances, just attempted to be
developed.
With equal probability did old cosmogonists say fossils were created, as
we now see them, with a false resemblance to living beings{105}; what would
the Astronomer say to the doctrine that the planets moved «not» according
to the law of gravitation, but from the Creator having willed each separate
planet to move in its particular orbit? I believe such a proposition (if we
remove all prejudices) would be as legitimate as to admit that certain
groups of living and extinct organisms, in their distribution, in their
structure and in their relations one to another and to external conditions,
agreed with the theory and showed signs of common descent, and yet were
created distinct. As long as it was thought impossible that organisms should
vary, or should anyhow become adapted to other organisms in a
complicated manner, and yet be separated from them by an impassable
barrier of sterility{106}, it was justifiable, even with some appearance in
favour of a common descent, to admit distinct creation according to the will
of an Omniscient Creator; or, for it is the same thing, to say with Whewell
that the beginnings of all things surpass the comprehension of man. In the
former sections I have endeavoured to show that such variation or
specification is not impossible, nay, in many points of view is absolutely
probable. What then is the evidence in favour of it and what the evidence
against it. With our imperfect knowledge of past ages [surely there will be

some] it would be strange if the imperfection did not create some
unfavourable evidence.
Give sketch of the Past,—beginning with facts appearing hostile under
present knowledge,—then proceed to geograph. distribution,—order of
appearance,—affinities,—morphology &c., &c.
Our theory requires a very gradual introduction of new forms{107}, and
extermination of the old (to which we shall revert). The extermination of
old may sometimes be rapid, but never the introduction. In the groups
descended from common parent, our theory requires a perfect gradation not
differing more than breed«s» of cattle, or potatoes, or cabbages in forms. I
do not mean that a graduated series of animals must have existed,
intermediate between horse, mouse, tapir{108}, elephant [or fowl and
peacock], but that these must have had a common parent, and between
horse and this «?» parent &c., &c., but the common parent may possibly
have differed more from either than the two do now from each other. Now
what evidence of this is there? So perfect gradation in some departments,
that some naturalists have thought that in some large divisions, if all
existing forms were collected, a near approach to perfect gradation would
be made. But such a notion is preposterous with respect to all, but evidently
so with mammals. Other naturalists have thought this would be so if all the
specimens entombed in the strata were collected{109}. I conceive there is no
probability whatever of this; nevertheless it is certain all the numerous
fossil forms fall in«to», as Buckland remarks, not present classes, families
and genera, they fall between them: so is it with new discoveries of existing
forms. Most ancient fossils, that is most separated «by» space of time, are
most apt to fall between the classes—(but organisms from those countries
most separated by space also fall between the classes «e.g.»
Ornithorhyncus?). As far as geological discoveries «go» they tend towards
such gradation{110}. Illustrate it with net. Toxodon,—tibia and fibula,—dog
and otter,—but so utterly improbable is «it», in ex. gr. Pachydermata, to
compose series as perfect as cattle, that if, as many geologists seem to infer,
each separate formation presents even an approach to a consecutive history,
my theory must be given up. Even if it were consecutive, it would only
collect series of one district in our present state of knowledge; but what
probability is there that any one formation during the immense period which
has elapsed during each period will generally present a consecutive history.

[Compare number living at one period to fossils preserved—look at
enormous periods of time.]
Referring only to marine animals, which are obviously most likely to be
preserved, they must live where «?» sediment (of a kind favourable for
preservation, not sand and pebble){111} is depositing quickly and over large
area and must be thickly capped, «illegible» littoral deposits: for otherwise
denudation «will destroy them»,—they must live in a shallow space which
sediment will tend to fill up,—as movement is «in?» progress if soon
brought «?» up «?» subject to denudation,—[if] as during subsidence
favourable, accords with facts of European deposits{112}, but subsidence apt
to destroy agents which produce sediment{113}.
I believe safely inferred «that» groups of marine «?» fossils only
preserved for future ages where sediment goes on long «and»
continuous«ly» and with rapid but not too rapid deposition in «an» area of
subsidence. In how few places in any one region like Europe will «?» these
contingencies be going on? Hence «?» in past ages mere [gaps] pages
preserved{114}. Lyell's doctrine carried to extreme,—we shall understand
difficulty if it be asked:—what chance of series of gradation between cattle
by «illegible» at age «illegible» as far back as Miocene{115}? We know then
cattle existed. Compare number of living,—immense duration of each
period,—fewness of fossils.
This only refers to consecutiveness of history of organisms of each
formation.
The foregoing argument will show firstly, that formations are distinct
merely from want of fossils «of intermediate beds», and secondly, that each
formation is full of gaps, has been advanced to account for fewness of
preserved organisms compared to what have lived on the world. The very
same argument explains why in older formations the organisms appear to
come on and disappear suddenly,—but in [later] tertiary not quite
suddenly{116}, in later tertiary gradually,—becoming rare and disappearing,
—some have disappeared within man’s time. It is obvious that our theory
requires gradual and nearly uniform introduction, possibly more sudden
extermination,—subsidence of continent of Australia &c., &c.

Our theory requires that the first form which existed of each of the great
divisions would present points intermediate between existing ones, but
immensely different. Most geologists believe Silurian{117} fossils are those
which first existed in the whole world, not those which have chanced to be
the oldest not destroyed,—or the first which existed in profoundly deep seas
in progress of conversion from sea to land: if they are first they «? we» give
up. Not so Hutton or Lyell: if first reptile{118} of Red Sandstone «?» really
was first which existed: if Pachyderm{119} of Paris was first which existed:
fish of Devonian: dragon fly of Lias: for we cannot suppose them the
progenitors: they agree too closely with existing divisions. But geologists
consider Europe as «?» a passage from sea to island «?» to continent
(except Wealden, see Lyell). These animals therefore, I consider then mere
introduction «?» from continents long since submerged.
Finally, if views of some geologists be correct, my theory must be given
up. [Lyell’s views, as far as they go, are in favour, but they go so little in
favour, and so much more is required, that it may «be» viewed as
objection.] If geology present us with mere pages in chapters, towards end
of «a» history, formed by tearing out bundles of leaves, and each page
illustrating merely a small portion of the organisms of that time, the facts
accord perfectly with my theory{120}.
Extermination. We have seen that in later periods the organisms have
disappeared by degrees and [perhaps] probably by degrees in earlier, and I
have said our theory requires it. As many naturalists seem to think
extermination a most mysterious circumstance{121} and call in astonishing
agencies, it is well to recall what we have shown concerning the struggle of
nature. An exterminating agency is at work with every organism: we
scarcely see it: if robins would increase to thousands in ten years how
severe must the process be. How imperceptible a small increase: fossils
become rare: possibly sudden extermination as Australia, but as present
means very slow and many means of escape, I shall doubt very sudden
exterminations. Who can explain why some species abound more,—why
does marsh titmouse, or ring-ouzel, now little change,—why is one sea-slug
rare and another common on our coasts,—why one species of Rhinoceros
more than another,—why is «illegible» tiger of India so rare? Curious and
general sources of error, the place of an organism is instantly filled up.

We know state of earth has changed, and as earthquakes and tides go on,
the state must change,—many geologists believe a slow gradual cooling.
Now let us see in accordance with principles of [variation] specification
explained in Sect. ii. how species would probably be introduced and how
such results accord with what is known.
The first fact geology proclaims is immense number of extinct forms,
and new appearances. Tertiary strata leads to belief, that forms gradually
become rare and disappear and are gradually supplied by others. We see
some forms now becoming rare and disappearing, we know of no sudden
creation: in older periods the forms appear to come in suddenly, scene
shifts: but even here Devonian, Permian &c. [keep on supplying new links
in chain]—Genera and higher forms come on and disappear, in same way
leaving a species on one or more stages below that in which the form
abounded.

«Geographical Distribution.»
§ vi. Let us consider the absolute state of distribution of
organisms of earth's face.
Referring chiefly, but not exclusively (from difficulty of transport,
fewness, and the distinct characteristics of groups) to Mammalia; and first
considering the three or four main [regions] divisions; North America,
Europe, Asia, including greater part of E. Indian Archipelago and Africa are
intimately allied. Africa most distinct, especially most southern parts. And
the Arctic regions, which unite N. America, Asia and Europe, only
separated (if we travel one way by Behring’s St.) by a narrow strait, is most
intimately allied, indeed forms but one restricted group. Next comes S.
America,—then Australia, Madagascar (and some small islands which stand
very remote from the land). Looking at these main divisions separately, the
organisms vary according to changes in condition{122} of different parts. But
besides this, barriers of every kind seem to separate regions in a greater
degree than proportionally to the difference of climates on each side. Thus
great chains of mountains, spaces of sea between islands and continents,
even great rivers and deserts. In fact the amount «of» difference in the
organisms bears a certain, but not invariable relation to the amount of
physical difficulties to transit{123}.

There are some curious exceptions, namely, similarity of fauna of
mountains of Europe and N. America and Lapland. Other cases just «the»
reverse, mountains of eastern S. America, Altai «?», S. India «?»{124}:
mountain summits of islands often eminently peculiar. Fauna generally of
some islands, even when close, very dissimilar, in others very similar. [I am
here led to observe one or more centres of creation{125}.]
The simple geologist can explain many of the foregoing cases of
distribution. Subsidence of a continent in which free means of dispersal,
would drive the lowland plants up to the mountains, now converted into
islands, and the semi-alpine plants would take place of alpine, and alpine be
destroyed, if mountains originally were not of great height. So we may see,
during gradual changes{126} of climate on a continent, the propagation of
species would vary and adapt themselves to small changes causing much
extermination{127}. The mountains of Europe were quite lately covered with
ice, and the lowlands probably partaking of the Arctic climate and Fauna.
Then as climate changed, arctic fauna would take place of ice, and an
inundation of plants from different temperate countries «would» seize the
lowlands, leaving islands of arctic forms. But if this had happened on an
island, whence could the new forms have come,—here the geologist calls in
creationists. If island formed, the geologist will suggest «that» many of the
forms might have been borne from nearest land, but if peculiar, he calls in
creationist,—as such island rises in height &c., he still more calls in
creation. The creationist tells one, on a «illegible» spot the American spirit
of creation makes Orpheus and Tyrannus and American doves, and in
accordance with past and extinct forms, but no persistent relation between
areas and distribution, Geologico-Geograph.-Distribution.
Now according to analogy of domesticated animals let us see what
would result. Let us take case of farmer on Pampas, where everything
approaches nearer to state of nature. He works on organisms having strong
tendency to vary: and he knows «that the» only way to make a distinct
breed is to select and separate. It would be useless to separate the best bulls
and pair with best cows if their offspring run loose and bred with the other
herds, and tendency to reversion not counteracted; he would endeavour
therefore to get his cows on islands and then commence his work of
selection. If several farmers in different rincons{128} were to set to work,
especially if with different objects, several breeds would soon be produced.

So would it be with horticulturist and so history of every plant shows; the
number of varieties{129} increase in proportion to care bestowed on their
selection and, with crossing plants, separation. Now, according to this
analogy, change of external conditions, and isolation either by chance
landing «of» a form on an island, or subsidence dividing a continent, or
great chain of mountains, and the number of individuals not being
numerous will best favour variation and selection{130}. No doubt change
could be effected in same country without any barrier by long continued
selection on one species: even in case of a plant not capable of crossing
would easier get possession and solely occupy an island{131}. Now we can at
once see that «if» two parts of a continent isolated, new species thus
generated in them, would have closest affinities, like cattle in counties of
England: if barrier afterwards destroyed one species might destroy the other
or both keep their ground. So if island formed near continent, let it be ever
so different, that continent would supply inhabitants, and new species (like
the old) would be allied with that continent. An island generally very
different soil and climate, and number and order of inhabitants supplied by
chance, no point so favourable for generation of new species{132},—
especially the mountains, hence, so it is. As isolated mountains formed in a
plain country (if such happens) is an island. As other islands formed, the old
species would spread and thus extend and the fauna of distant island might
ultimately meet and a continent formed between them. No one doubts
continents formed by repeated elevations and depressions{133}. In looking
backwards, but not so far that all geographical boundaries are destroyed, we
can thus at once see why existing forms are related to the extinct in the
same manner as existing ones are in some part of existing continent. By
chance we might even have one or two absolute parent fossils.
The detection of transitional forms would be rendered more difficult on
rising point of land.
The distribution therefore in the above enumerated points, even the
trivial ones, which on any other «theory?» can be viewed as so many
ultimate facts, all follow «in» a simple manner on the theory of the
occurrence of species by «illegible» and being adapted by selection to
«illegible», conjoined with their power of dispersal, and the steady
geographico-geological changes which are now in progress and which
undoubtedly have taken place. Ought to state the opinion of the

immutability of species and the creation by so many separate acts of will of
the Creator{134}.

§ VII. «Affinities and Classification.»
Looking now to the affinities of organisms, without relation to their
distribution, and taking all fossil and recent, we see the degrees of
relationship are of different degrees and arbitrary,—sub-genera,—genera,—
sub-families, families, orders and classes and kingdoms. The kind of
classification which everyone feels is most correct is called the natural
system, but no can define this. If we say with Whewell «that we have an»
undefined instinct of the importance of organs{135}, we have no means in
lower animals of saying which is most important, and yet everyone feels
that some one system alone deserves to be called natural. The true
relationship of organisms is brought before one by considering relations of
analogy, an otter-like animal amongst mammalia and an otter amongst
marsupials. In such cases external resemblance and habit of life and the
final end of whole organization very strong, yet no relation{136}. Naturalists
cannot avoid these terms of relation and affinity though they use them
metaphorically. If used in simple earnestness the natural system ought to be
a genealogical «one»; and our knowledge of the points which are most
easily affected in transmission are those which we least value in considering
the natural system, and practically when we find they do vary we regard
them of less value{137}. In classifying varieties the same language is used
and the same kind of division: here also (in pine-apple){138} we talk of the
natural classification, overlooking similarity of the fruits, because whole
plant differs. The origin of sub-genera, genera, &c., &c., is not difficult on
notion of genealogical succession, and accords with what we know of
similar gradations of affinity in domesticated organisms. In the same region
the organic beings are «illegible» related to each other and the external
conditions in many physical respects are allied{139} and their differences of
same kind, and therefore when a new species has been selected and has
obtained a place in the economy of nature, we may suppose that generally it
will tend to extend its range during geographical changes, and thus,
becoming isolated and exposed to new conditions, will slightly alter and its
structure by selection become slightly remodified, thus we should get
species of a sub-genus and genus,—as varieties of merino-sheep,—varieties
of British and Indian cattle. Fresh species might go on forming and others

become extinct and all might become extinct, and then we should have «an»
extinct genus; a case formerly mentioned, of which numerous cases occur
in Palæontology. But more often the same advantages which caused the
new species to spread and become modified into several species would
favour some of the species being preserved: and if two of the species,
considerably different, each gave rise to group of new species, you would
have two genera; the same thing will go on. We may look at case in other
way, looking to future. According to mere chance every existing species
may generate another, but if any species, A, in changing gets an advantage
and that advantage (whatever it may be, intellect, &c., &c., or some
particular structure or constitution) is inherited{140}, A will be the progenitor
of several genera or even families in the hard struggle of nature. A will go
on beating out other forms, it might come that A would people earth,—we
may now not have one descendant on our globe of the one or several
original creations{141}. External conditions air, earth, water being same{142}
on globe, and the communication not being perfect, organisms of widely
different descent might become adapted to the same end and then we should
have cases of analogy{143}, [they might even tend to become numerically
representative]. From this often happening each of the great divisions of
nature would have their representative eminently adapted to earth, to
«air»{144}, to water, and to these in «illegible» and then these great divisions
would show numerical relations in their classification.

§ VIII. Unity [or similarity] of type in the great classes.
Nothing more wonderful in Nat. Hist. than looking at the vast number
of organisms, recent and fossil, exposed to the most diverse conditions,
living in the most distant climes, and at immensely remote periods, fitted to
wholely different ends, yet to find large groups united by a similar type of
structure. When we for instance see bat, horse, porpoise-fin, hand, all built
on same structure{145}, having bones{146} with same name, we see there is
some deep bond of union between them{147}, to illustrate this is the
foundation and objects «?» «of» what is called the Natural System; and
which is foundation of distinction «?» of true and adaptive characters{148}.
Now this wonderful fact of hand, hoof, wing, paddle and claw being the
same, is at once explicable on the principle of some parent-forms, which
might either be «illegible» or walking animals, becoming through infinite
number of small selections adapted to various conditions. We know that

proportion, size, shape of bones and their accompanying soft parts vary, and
hence constant selection would alter, to almost any purpose «?» the
framework of an organism, but yet would leave a general, even closest
similarity in it.
[We know the number of similar parts, as vertebræ and ribs can vary,
hence this also we might expect.] Also «if» the changes carried on to a
certain point, doubtless type will be lost, and this is case with
Plesiosaurus{149}. The unity of type in past and present ages of certain great
divisions thus undoubtedly receives the simplest explanation.
There is another class of allied and almost identical facts, admitted by
the soberest physiologists, [from the study of a certain set of organs in a
group of organisms] and refers «? referring» to a unity of type of different
organs in the same individual, denominated the science of “Morphology.”
The «? this» discovered by beautiful and regular series, and in the case of
plants from monstrous changes, that certain organs in an individual are
other organs metamorphosed. Thus every botanist considers petals,
nectaries, stamens, pistils, germen as metamorphosed leaf. They thus
explain, in the most lucid manner, the position and number of all parts of
the flower, and the curious conversion under cultivation of one part into
another. The complicated double set of jaws and palpi of crustaceans{150},
and all insects are considered as metamorphosed «limbs» and to see the
series is to admit this phraseology. The skulls of the vertebrates are
undoubtedly composed of three metamorphosed vertebræ; thus we can
understand the strange form of the separate bones which compose the
casket holding man’s brain. These{151} facts differ but slightly from those of
last section, if with wing, paddle, hand and hoof, some common structure
was yet visible, or could be made out by a series of occasional monstrous
conversions, and if traces could be discovered of «the» whole having once
existed as walking or swimming instruments, these organs would be said to
be metamorphosed, as it is they are only said to exhibit a common type.
This distinction is not drawn by physiologists, and is only implied by
some by their general manner of writing. These facts, though affecting
every organic being on the face of the globe, which has existed, or does
exist, can only be viewed by the Creationist as ultimate and inexplicable
facts. But this unity of type through the individuals of a group, and this

metamorphosis of the same organ into other organs, adapted to diverse use,
necessarily follows on the theory of descent{152}. For let us take case of
Vertebrata, which if{153} they descended from one parent and by this theory
all the Vertebrata have been altered by slow degrees, such as we see in
domestic animals. We know that proportions alter, and even that
occasionally numbers of vertebræ alter, that parts become soldered, that
parts are lost, as tail and toes, but we know «that?» here we can see that
possibly a walking organ might «?» be converted into swimming or into a
gliding organ and so on to a flying organ. But such gradual changes would
not alter the unity of type in their descendants, as parts lost and soldered
and vertebræ. But we can see that if this carried to extreme, unity lost,—
Plesiosaurus. Here we have seen the same organ is formed «?» «for»
different purposes «ten words illegible»: and if, in several orders of
vertebrata, we could trace origin «of» spinous processes and monstrosities
&c. we should say, instead of there existing a unity of type, morphology{154},
as we do when we trace the head as being the vertebræ metamorphosed. Be
it observed that Naturalists, as they use terms of affinity without attaching
real meaning, here also they are obliged to use metamorphosis, without
meaning that any parent of crustacean was really an animal with as many
legs as crustacean has jaws. The theory of descent at once explains these
wonderful facts.
Now few of the physiologists who use this language really suppose that
the parent of insect with the metamorphosed jaw, was an insect with [more]
so many legs, or that the parent of flowering plants, originally had no
stamens, or pistils or petals, but some other means of propagation,—and so
in other cases. Now according to our theory during the infinite number of
changes, we might expect that an organ used for a purpose might be used
for a different one by his descendant, as must have been the case by our
theory with the bat, porpoise, horse, &c., which are descended from one
parent. And if it so chanced that traces of the former use and structure of the
part should be retained, which is manifestly possible if not probable, then
we should have the organs, on which morphology is founded and which
instead of being metaphorical becomes plain and «and instead of being»
utterly unintelligible becomes simple matter of fact{155}.
«Embryology.» This general unity of type in great groups of organisms
(including of course these morphological cases) displays itself in a most

striking manner in the stages through which the fœtus passes{156}. In early
stage, the wing of bat, hoof, hand, paddle are not to be distinguished. At a
still earlier «stage» there is no difference between fish, bird, &c. &c. and
mammal. It is not that they cannot be distinguished, but the arteries{157}
«illegible». It is not true that one passes through the form of a lower group,
though no doubt fish more nearly related to fœtal state{158}.
This similarity at the earliest stage is remarkably shown in the course of
the arteries which become greatly altered, as fœtus advances in life and
assumes the widely different course and number which characterize full-
grown fish and mammals. How wonderful that in egg, in water or air, or in
womb of mother, artery{159} should run in same course.
Light can be thrown on this by our theory. The structure of each
organism is chiefly adapted to the sustension of its life, when full-grown,
when it has to feed itself and propagate{160}. The structure of a kitten is quite
in secondary degree adapted to its habits, whilst fed by its mother’s milk
and prey. Hence variation in the structure of the full-grown species will
chiefly determine the preservation of a species now become ill-suited to its
habitat, or rather with a better place opened to it in the economy of Nature.
It would not matter to the full-grown cat whether in its young state it was
more or less eminently feline, so that it become so when full-grown. No
doubt most variation, (not depending on habits of life of individual)
depends on early change{161} and we must suspect that at whatever time of
life the alteration of fœtus is effected, it tends to appear at same period.
When we «see» a tendency to particular disease in old age transmitted by
the male, we know some effect is produced during conception, on the
simple cell of ovule, which will not produce its effect till half a century
afterwards and that effect is not visible{162}. So we see in grey-hound, bull-
dog, in race-horse and cart-horse, which have been selected for their form
in full-life, there is much less «?» difference in the few first days after
birth{163}, than when full-grown: so in cattle, we see it clearly in cases of
cattle, which differ obviously in shape and length of horns. If man were
during 10,000 years to be able to select, far more diverse animals from
horse or cow, I should expect there would be far less differences in the very
young and fœtal state: and this, I think, throws light on above marvellous
fact. In larvæ, which have long life selection, perhaps, does much,—in the
pupa not so much{164} There is no object gained in varying form &c. of

fœtus (beyond certain adaptations to mother’s womb) and therefore
selection will not further act on it, than in giving to its changing tissues a
tendency to certain parts afterwards to assume certain forms.
Thus there is no power to change the course of the arteries, as long as
they nourish the fœtus; it is the selection of slight changes which supervene
at any time during «illegible» of life.
The less differences of fœtus,—this has obvious meaning on this view:
otherwise how strange that a [monkey] horse, a man, a bat should at one
time of life have arteries, running in a manner, which is only intelligibly
useful in a fish! The natural system being on theory genealogical, we can at
once see, why fœtus, retaining traces of the ancestral form, is of the highest
value in classification.

§ IX. «Abortive organs.»
There is another grand class of facts relating to what are called abortive
organs. These consist of organs which the same reasoning power that shows
us how beautifully these organs in some cases are adapted to certain end,
declares in other cases are absolutely useless. Thus teeth in Rhinoceros{165},
whale, narwhal,—bone on tibia, muscles which do not move,—little bone
of wing of Apteryx,—bone representing extremities in some snake,—little
wings within «?» soldered cover of beetles,—men and bulls, mammæ:
filaments without anthers in plants, mere scales representing petals in
others, in feather-hyacinth whole flower. Almost infinitely numerous. No
one can reflect on these without astonishment, can anything be clearer than
that wings are to fly and teeth «to bite», and yet we find these organs
perfect in every detail in situations where they cannot possibly be of their
normal use{166}.
The term abortive organ has been thus applied to above structure (as
invariable as all other parts{167}) from their absolute similarity to monstrous
cases, where from accident, certain organs are not developed; as infant
without arms or fingers with mere stump representing them: teeth
represented by mere points of ossification: headless children with mere
button,—viscera represented by small amorphous masses, &c.,—the tail by
mere stump,—a solid horn by minute hanging one{168}. There is a tendency
in all these cases, when life is preserved, for such structures to become

hereditary. We see it in tailless dogs and cats. In plants we see this
strikingly,—in Thyme, in Linum flavum,—stamen in Geranium
pyrenaicum{169}. Nectaries abort into petals in Columbine «Aquilegia»,
produced from some accident and then become hereditary, in some cases
only when propagated by buds, in other cases by seed. These cases have
been produced suddenly by accident in early growth, but it is part of law of
growth that when any organ is not used it tends to diminish (duck’s
wing{170}?) muscles of dog’s ears, «and of» rabbits, muscles wither, arteries
grow up. When eye born defective, optic nerve (Tuco Tuco) is atrophied. As
every part whether useful or not (diseases, double flowers) tends to be
transmitted to offspring, the origin of abortive organs whether produced at
the birth or slowly acquired is easily understood in domestic races of
organisms: [a struggle between the atrophy and hereditariness. Abortive
organs in domestic races.] There will always be a struggle between atrophy
of an organ rendered useless, and hereditariness{171}. Because we can
understand the origin of abortive organs in certain cases, it would be wrong
to conclude absolutely that all must have had same origin, but the strongest
analogy is in favour of it. And we can by our theory, for during infinite
changes some organ, we might have anticipated, would have become
useless. «We can» readily explain the fact, so astounding on any other view,
namely that organs possibly useless have been formed often with the same
exquisite care as when of vital importance.
Our theory, I may remark would permit an organ «to» become abortive
with respect to its primary use, to be turned to any other purpose, (as the
buds in a cauliflower) thus we can see no difficulty in bones of male
marsupials being used as fulcrum of muscles, or style of marygold{172},—
indeed in one point of view, the heads of [vertebrated] animal may be said
to be abortive vertebræ turned into other use: legs of some crustacea
abortive jaws, &c., &c. De Candolle's analogy of table covered with
dishes{173}.
«The following passage was possibly intended to be inserted here.»
Degradation and complication see Lamarck: no tendency to perfection: if
room, [even] high organism would have greater power in beating lower one,
thought «?» to be selected for a degraded end.

§ X. Recapitulation and conclusion.

Let us recapitulate the whole «?» «of» these latter sections by taking
case of the three species of Rhinoceros, which inhabit Java, Sumatra, and
mainland of Malacca or India. We find these three close neighbours,
occupants of distinct but neighbouring districts, as a group having a
different aspect from the Rhinoceros of Africa, though some of these latter
inhabit very similar countries, but others most diverse stations. We find
them intimately related [scarcely «?» differences more than some breeds of
cattle] in structure to the Rhinoceros, which for immense periods have
inhabited this one, out of three main zoological divisions of the world. Yet
some of these ancient animals were fitted to very different stations: we find
all three «illegible» of the generic character of the Rhinoceros, which form
a [piece of net]{174} set of links in the broken chain representing the
Pachydermata, as the chain likewise forms a portion in other and longer
chains. We see this wonderfully in dissecting the coarse leg of all three and
finding nearly the same bones as in bat’s wings or man’s hand, but we see
the clear mark in solid tibia of the fusion into it of the fibula. In all three we
find their heads composed of three altered vertebræ, short neck, same bones
as giraffe. In the upper jaws of all three we find small teeth like rabbit’s. In
dissecting them in fœtal state we find at a not very early stage their form
exactly alike the most different animals, and even with arteries running as
in a fish: and this similarity holds when the young one is produced in
womb, pond, egg or spawn. Now these three undoubted species scarcely
differ more than breeds of cattle, are probably subject to many the same
contagious diseases; if domesticated these forms would vary, and they
might possibly breed together, and fuse into something{175} different «from»
their aboriginal forms; might be selected to serve different ends.
Now the Creationist believes these three Rhinoceroses were created{176}
with their deceptive appearance of true, not «illegible» relationship; as well
can I believe the planets revolve in their present courses not from one law
of gravity but from distinct volition of Creator.
If real species, sterile one with another, differently adapted, now
inhabiting different countries, with different structures and instincts, are
admitted to have common descent, we can only legitimately stop where our
facts stop. Look how far in some case a chain of species will lead us. «This
probably refers to the Crustacea, where the two ends of the series have
“hardly a character in common.” Origin, Ed. i. p. 419.» May we not jump

(considering how much extermination, and how imperfect geological
records) from one sub-genus to another sub-genus. Can genera restrain us;
many of the same arguments, which made us give up species, inexorably
demand genera and families and orders to fall, and classes tottering. We
ought to stop only when clear unity of type, independent of use and
adaptation, ceases.
Be it remembered no naturalist pretends to give test from external
characters of species; in many genera the distinction is quite arbitrary{177}.
But there remains one other way of comparing species with races; it is to
compare the effects of crossing them. Would it not be wonderful, if the
union of two organisms, produced by two separate acts of Creation, blended
their characters together when crossed according to the same rules, as two
races which have undoubtedly descended from same parent stock; yet this
can be shown to be the case. For sterility, though a usual «?», is not an
invariable concomitant, it varies much in degree and has been shown to be
probably dependent on causes closely analogous with those which make
domesticated organisms sterile. Independent of sterility there is no
difference between mongrels and hybrids, as can be shown in a long series
of facts. It is strikingly seen in cases of instincts, when the minds of the two
species or races become blended together{178}. In both cases if the half-breed
be crossed with either parent for a few generations, all traces of the one
parent form is lost (as Kölreuter in two tobacco species almost sterile
together), so that the Creationist in the case of a species, must believe that
one act of creation is absorbed into another!

Facsimile of the original manuscript of the paragraph on p. 50.
Conclusion.
Such are my reasons for believing that specific forms are not
immutable. The affinity of different groups, the unity of types of structure,
the representative forms through which fœtus passes, the metamorphosis of
organs, the abortion of others cease to be metaphorical expressions and
become intelligible facts. We no longer look «an» on animal as a savage
does at a ship{179}, or other great work of art, as a thing wholly beyond
comprehension, but we feel far more interest in examining it. How
interesting is every instinct, when we speculate on their origin as an
hereditary or congenital habit or produced by the selection of individuals
differing slightly from their parents. We must look at every complicated
mechanism and instinct, as the summary of a long history, «as the summing
up» of{180} useful contrivances, much like a work of art. How interesting
does the distribution of all animals become, as throwing light on ancient
geography. [We see some seas bridged over.] Geology loses in its glory
from the imperfection of its archives{181}, but how does it gain in the
immensity of the periods of its formations and of the gaps separating these
formations. There is much grandeur in looking at the existing animals either
as the lineal descendants of the forms buried under thousand feet of matter,
or as the coheirs of some still more ancient ancestor. It accords with what
we know of the law impressed on matter by the Creator, that the creation
and extinction of forms, like the birth and death of individuals should be the

effect of secondary [laws] means{182}. It is derogatory that the Creator of
countless systems of worlds should have created each of the myriads of
creeping parasites and [slimy] worms which have swarmed each day of life
on land and water «on» [this] one globe. We cease being astonished,
however much we may deplore, that a group of animals should have been
directly created to lay their eggs in bowels and flesh of other,—that some
organisms should delight in cruelty,—that animals should be led away by
false instincts,—that annually there should be an incalculable waste of eggs
and pollen. From death, famine, rapine, and the concealed war of nature we
can see that the highest good, which we can conceive, the creation of the
higher animals has directly come. Doubtless it at first transcends our
humble powers, to conceive laws capable of creating individual organisms,
each characterised by the most exquisite workmanship and widely-extended
adaptations. It accords better with [our modesty] the lowness of our
faculties to suppose each must require the fiat of a creator, but in the same
proportion the existence of such laws should exalt our notion of the power
of the omniscient Creator{183}. There is a simple grandeur in the view of life
with its powers of growth, assimilation and reproduction, being originally
breathed into matter under one or a few forms, and that whilst this our
planet has gone circling on according to fixed laws, and land and water, in a
cycle of change, have gone on replacing each other, that from so simple an
origin, through the process of gradual selection of infinitesimal changes,
endless forms most beautiful and most wonderful have been evolved{184}.
N.B.—There ought somewhere to be a discussion from Lyell to show
that external conditions do vary, or a note to Lyell's works «work?».
Besides other difficulties in ii. Part, non-acclimatisation of plants.
Difficulty when asked how did white and negro become altered from
common intermediate stock: no facts. We do not know that species are
immutable, on the contrary. What arguments against this theory, except our
not perceiving every step, like the erosion of valleys{185}.

THE ESSAY OF 1844

PART I

CHAPTER I
on the variation of organic beings under
domestication; and on the principles of selection

The most favourable conditions for variation seem to be when organic
beings are bred for many generations under domestication{186}: one may
infer this from the simple fact of the vast number of races and breeds of
almost every plant and animal, which has long been domesticated. Under
certain conditions organic beings even during their individual lives become
slightly altered from their usual form, size, or other characters: and many of
the peculiarities thus acquired are transmitted to their offspring. Thus in
animals, the size and vigour of body, fatness, period of maturity, habits of
body or consensual movements, habits of mind and temper, are modified or
acquired during the life of the individual{187}, and become inherited. There is
reason to believe that when long exercise has given to certain muscles great
development, or disuse has lessened them, that such development is also
inherited. Food and climate will occasionally produce changes in the colour
and texture of the external coverings of animals; and certain unknown
conditions affect the horns of cattle in parts of Abyssinia; but whether these
peculiarities, thus acquired during individual lives, have been inherited, I do
not know. It appears certain that malconformation and lameness in horses,
produced by too much work on hard roads,—that affections of the eyes in
this animal probably caused by bad ventilation,—that tendencies towards
many diseases in man, such as gout, caused by the course of life and
ultimately producing changes of structure, and that many other diseases
produced by unknown agencies, such as goitre, and the idiotcy resulting
from it, all become hereditary.
It is very doubtful whether the flowers and leaf-buds, annually produced
from the same bulb, root, or tree, can properly be considered as parts of the
same individual, though in some respects they certainly seem to be so. If
they are parts of an individual, plants also are subject to considerable
changes during their individual lives. Most florist-flowers if neglected
degenerate, that is, they lose some of their characters; so common is this,

that trueness is often stated, as greatly enhancing the value of a variety{188}:
tulips break their colours only after some years’ culture; some plants
become double and others single, by neglect or care: these characters can be
transmitted by cuttings or grafts, and in some cases by true or seminal
propagation. Occasionally a single bud on a plant assumes at once a new
and widely different character: thus it is certain that nectarines have been
produced on peach trees and moss roses on provence roses; white currants
on red currant bushes; flowers of a different colour from that of the stock, in
Chrysanthemums, Dahlias, sweet-williams, Azaleas, &c., &c.; variegated
leaf-buds on many trees, and other similar cases. These new characters
appearing in single buds, can, like those lesser changes affecting the whole
plant, be multiplied not only by cuttings and such means, but often likewise
by true seminal generation.
The changes thus appearing during the lives of individual animals and
plants are extremely rare compared with those which are congenital or
which appear soon after birth. Slight differences thus arising are infinitely
numerous: the proportions and form of every part of the frame, inside and
outside, appear to vary in very slight degrees: anatomists dispute what is the
“beau ideal” of the bones, the liver and kidneys, like painters do of the
proportions of the face: the proverbial expression that no two animals or
plants are born absolutely alike, is much truer when applied to those under
domestication, than to those in a state of nature{189}. Besides these slight
differences, single individuals are occasionally born considerably unlike in
certain parts or in their whole structure to their parents: these are called by
horticulturists and breeders “sports”; and are not uncommon except when
very strongly marked. Such sports are known in some cases to have been
parents of some of our domestic races; and such probably have been the
parents of many other races, especially of those which in some senses may
be called hereditary monsters; for instance where there is an additional
limb, or where all the limbs are stunted (as in the Ancon sheep), or where a
part is wanting, as in rumpless fowls and tailless dogs or cats{190}. The
effects of external conditions on the size, colour and form, which can rarely
and obscurely be detected during one individual life, become apparent after
several generations: the slight differences, often hardly describable, which
characterize the stock of different countries, and even of districts in the
same country, seem to be due to such continued action.

On the hereditary tendency.
A volume might be filled with facts showing what a strong tendency
there is to inheritance, in almost every case of the most trifling, as well as of
the most remarkable congenital peculiarities{191}. The term congenital
peculiarity, I may remark, is a loose expression and can only mean a
peculiarity apparent when the part affected is nearly or fully developed: in
the Second Part, I shall have to discuss at what period of the embryonic life
connatal peculiarities probably first appear; and I shall then be able to show
from some evidence, that at whatever period of life a new peculiarity first
appears, it tends hereditarily to appear at a corresponding period{192}.
Numerous though slight changes, slowly supervening in animals during
mature life (often, though by no means always, taking the form of disease),
are, as stated in the first paragraphs, very often hereditary. In plants, again,
the buds which assume a different character from their stock likewise tend
to transmit their new peculiarities. There is not sufficient reason to believe
that either mutilations{193} or changes of form produced by mechanical
pressure, even if continued for hundreds of generations, or that any changes
of structure quickly produced by disease, are inherited; it would appear as if
the tissue of the part affected must slowly and freely grow into the new
form, in order to be inheritable. There is a very great difference in the
hereditary tendency of different peculiarities, and of the same peculiarity, in
different individuals and species; thus twenty thousand seeds of the
weeping ash have been sown and not one come up true;—out of seventeen
seeds of the weeping yew, nearly all came up true. The ill-formed and
almost monstrous “Niata” cattle of S. America and Ancon sheep, both when
bred together and when crossed with other breeds, seem to transmit their
peculiarities to their offspring as truly as the ordinary breeds. I can throw no
light on these differences in the power of hereditary transmission. Breeders
believe, and apparently with good cause, that a peculiarity generally
becomes more firmly implanted after having passed through several
generations; that is if one offspring out of twenty inherits a peculiarity from
its parents, then its descendants will tend to transmit this peculiarity to a
larger proportion than one in twenty; and so on in succeeding generations. I
have said nothing about mental peculiarities being inheritable for I reserve
this subject for a separate chapter.

Causes of Variation.
Attention must here be drawn to an important distinction in the first
origin or appearance of varieties: when we see an animal highly kept
producing offspring with an hereditary tendency to early maturity and
fatness; when we see the wild-duck and Australian dog always becoming,
when bred for one or a few generations in confinement, mottled in their
colours; when we see people living in certain districts or circumstances
becoming subject to an hereditary taint to certain organic diseases, as
consumption or plica polonica,—we naturally attribute such changes to the
direct effect of known or unknown agencies acting for one or more
generations on the parents. It is probable that a multitude of peculiarities
may be thus directly caused by unknown external agencies. But in breeds,
characterized by an extra limb or claw, as in certain fowls and dogs; by an
extra joint in the vertebræ; by the loss of a part, as the tail; by the
substitution of a tuft of feathers for a comb in certain poultry; and in a
multitude of other cases, we can hardly attribute these peculiarities directly
to external influences, but indirectly to the laws of embryonic growth and of
reproduction. When we see a multitude of varieties (as has often been the
case, where a cross has been carefully guarded against) produced from
seeds matured in the very same capsule{194}, with the male and female
principle nourished from the same roots and necessarily exposed to the
same external influences; we cannot believe that the endless slight
differences between seedling varieties thus produced, can be the effect of
any corresponding difference in their exposure. We are led (as Müller has
remarked) to the same conclusion, when we see in the same litter, produced
by the same act of conception, animals considerably different.
As variation to the degree here alluded to has been observed only in
organic beings under domestication, and in plants amongst those most
highly and long cultivated, we must attribute, in such cases, the varieties
(although the difference between each variety cannot possibly be attributed
to any corresponding difference of exposure in the parents) to the indirect
effects of domestication on the action of the reproductive system{195}. It
would appear as if the reproductive powers failed in their ordinary function
of producing new organic beings closely like their parents; and as if the
entire organization of the embryo, under domestication, became in a slight
degree plastic{196}. We shall hereafter have occasion to show, that in organic

beings, a considerable change from the natural conditions of life, affects,
independently of their general state of health, in another and remarkable
manner the reproductive system. I may add, judging from the vast number
of new varieties of plants which have been produced in the same districts
and under nearly the same routine of culture, that probably the indirect
effects of domestication in making the organization plastic, is a much more
efficient source of variation than any direct effect which external causes
may have on the colour, texture, or form of each part. In the few instances
in which, as in the Dahlia{197}, the course of variation has been recorded, it
appears that domestication produces little effect for several generations in
rendering the organization plastic; but afterwards, as if by an accumulated
effect, the original character of the species suddenly gives way or breaks.

On Selection.
We have hitherto only referred to the first appearance in individuals of
new peculiarities; but to make a race or breed, something more is
generally{198} requisite than such peculiarities (except in the case of the
peculiarities being the direct effect of constantly surrounding conditions)
should be inheritable,—namely the principle of selection, implying
separation. Even in the rare instances of sports, with the hereditary tendency
very strongly implanted, crossing must be prevented with other breeds, or if
not prevented the best characterized of the half-bred offspring must be
carefully selected. Where the external conditions are constantly tending to
give some character, a race possessing this character will be formed with far
greater ease by selecting and breeding together the individuals most
affected. In the case of the endless slight variations produced by the indirect
effects of domestication on the action of the reproductive system, selection
is indispensable to form races; and when carefully applied, wonderfully
numerous and diverse races can be formed. Selection, though so simple in
theory, is and has been important to a degree which can hardly be overrated.
It requires extreme skill, the results of long practice, in detecting the
slightest difference in the forms of animals, and it implies some distinct
object in view; with these requisites and patience, the breeder has simply to
watch for every the smallest approach to the desired end, to select such
individuals and pair them with the most suitable forms, and so continue
with succeeding generations. In most cases careful selection and the
prevention of accidental crosses will be necessary for several generations,

for in new breeds there is a strong tendency to vary and especially to revert
to ancestral forms: but in every succeeding generation less care will be
requisite for the breed will become truer; until ultimately only an occasional
individual will require to be separated or destroyed. Horticulturalists in
raising seeds regularly practise this, and call it “roguing,” or destroying the
“rogues” or false varieties. There is another and less efficient means of
selection amongst animals: namely repeatedly procuring males with some
desirable qualities, and allowing them and their offspring to breed freely
together; and this in the course of time will affect the whole lot. These
principles of selection have been methodically followed for scarcely a
century; but their high importance is shown by the practical results, and is
admitted in the writings of the most celebrated agriculturalists and
horticulturalists;—I need only name Anderson, Marshall, Bakewell, Coke,
Western, Sebright and Knight.
Even in well-established breeds the individuals of which to an
unpractised eye would appear absolutely similar, which would give, it
might have been thought, no scope to selection, the whole appearance of the
animal has been changed in a few years (as in the case of Lord Western’s
sheep), so that practised agriculturalists could scarcely credit that a change
had not been effected by a cross with other breeds. Breeders both of plants
and animals frequently give their means of selection greater scope, by
crossing different breeds and selecting the offspring; but we shall have to
recur to this subject again.
The external conditions will doubtless influence and modify the results
of the most careful selection; it has been found impossible to prevent
certain breeds of cattle from degenerating on mountain pastures; it would
probably be impossible to keep the plumage of the wild-duck in the
domesticated race; in certain soils, no care has been sufficient to raise
cauliflower seed true to its character; and so in many other cases. But with
patience it is wonderful what man has effected. He has selected and
therefore in one sense made one breed of horses to race and another to pull;
he has made sheep with fleeces good for carpets and other sheep good for
broadcloth; he has, in the same sense, made one dog to find game and give
him notice when found, and another dog to fetch him the game when killed;
he has made by selection the fat to lie mixed with the meat in one breed and
in another to accumulate in the bowels for the tallow-chandler{199}; he has

made the legs of one breed of pigeons long, and the beak of another so
short, that it can hardly feed itself; he has previously determined how the
feathers on a bird’s body shall be coloured, and how the petals of many
flowers shall be streaked or fringed, and has given prizes for complete
success;—by selection, he has made the leaves of one variety and the
flower-buds of another variety of the cabbage good to eat, at different
seasons of the year; and thus has he acted on endless varieties. I do not wish
to affirm that the long-and short-wooled sheep, or that the pointer and
retriever, or that the cabbage and cauliflower have certainly descended from
one and the same aboriginal wild stock; if they have not so descended,
though it lessens what man has effected, a large result must be left
unquestioned.
In saying as I have done that man makes a breed, let it not be
confounded with saying that man makes the individuals, which are given by
nature with certain desirable qualities; man only adds together and makes a
permanent gift of nature’s bounties. In several cases, indeed, for instance in
the “Ancon” sheep, valuable from not getting over fences, and in the
turnspit dog, man has probably only prevented crossing; but in many cases
we positively know that he has gone on selecting, and taking advantage of
successive small variations.
Selection{200} has been methodically followed, as I have said, for barely
a century; but it cannot be doubted that occasionally it has been practised
from the remotest ages, in those animals completely under the dominion of
man. In the earliest chapters of the Bible there are rules given for
influencing the colours of breeds, and black and white sheep are spoken of
as separated. In the time of Pliny the barbarians of Europe and Asia
endeavoured by cross-breeding with a wild stock to improve the races of
their dogs and horses. The savages of Guyana now do so with their dogs:
such care shows at least that the characters of individual animals were
attended to. In the rudest times of English history, there were laws to
prevent the exportation of fine animals of established breeds, and in the
case of horses, in Henry VIII’s time, laws for the destruction of all horses
under a certain size. In one of the oldest numbers of the Phil. Transactions,
there are rules for selecting and improving the breeds of sheep. Sir H.
Bunbury, in 1660, has given rules for selecting the finest seedling plants,
with as much precision as the best recent horticulturalist could. Even in the

most savage and rude nations, in the wars and famines which so frequently
occur, the most useful of their animals would be preserved: the value set
upon animals by savages is shown by the inhabitants of Tierra del Fuego
devouring their old women before their dogs, which as they asserted are
useful in otter-hunting{201}: who can doubt but that in every case of famine
and war, the best otter-hunters would be preserved, and therefore in fact
selected for breeding. As the offspring so obviously take after their parents,
and as we have seen that savages take pains in crossing their dogs and
horses with wild stocks, we may even conclude as probable that they would
sometimes pair the most useful of their animals and keep their offspring
separate. As different races of men require and admire different qualities in
their domesticated animals, each would thus slowly, though unconsciously,
be selecting a different breed. As Pallas has remarked, who can doubt but
that the ancient Russian would esteem and endeavour to preserve those
sheep in his flocks which had the thickest coats. This kind of insensible
selection by which new breeds are not selected and kept separate, but a
peculiar character is slowly given to the whole mass of the breed, by often
saving the life of animals with certain characteristics, we may feel nearly
sure, from what we see has been done by the more direct method of
separate selection within the last 50 years in England, would in the course
of some thousand years produce a marked effect.

Crossing Breeds.
When once two or more races are formed, or if more than one race, or
species fertile inter se, originally existed in a wild state, their crossing
becomes a most copious source of new races{202}. When two well-marked
races are crossed the offspring in the first generation take more or less after
either parent or are quite intermediate between them, or rarely assume
characters in some degree new. In the second and several succeeding
generations, the offspring are generally found to vary exceedingly, one
compared with another, and many revert nearly to their ancestral forms.
This greater variability in succeeding generations seems analogous to the
breaking or variability of organic beings after having been bred for some
generations under domestication{203}. So marked is this variability in cross-
bred descendants, that Pallas and some other naturalists have supposed that
all variation is due to an original cross; but I conceive that the history of the
potato, Dahlia, Scotch Rose, the guinea-pig, and of many trees in this

country, where only one species of the genus exists, clearly shows that a
species may vary where there can have been no crossing. Owing to this
variability and tendency to reversion in cross-bred beings, much careful
selection is requisite to make intermediate or new permanent races:
nevertheless crossing has been a most powerful engine, especially with
plants, where means of propagation exist by which the cross-bred varieties
can be secured without incurring the risk of fresh variation from seminal
propagation: with animals the most skilful agriculturalists now greatly
prefer careful selection from a well-established breed, rather than from
uncertain cross-bred stocks.
Although intermediate and new races may be formed by the mingling of
others, yet if the two races are allowed to mingle quite freely, so that none
of either parent race remain pure, then, especially if the parent races are not
widely different, they will slowly blend together, and the two races will be
destroyed, and one mongrel race left in its place. This will of course happen
in a shorter time, if one of the parent races exists in greater number than the
other. We see the effect of this mingling, in the manner in which the
aboriginal breeds of dogs and pigs in the Oceanic Islands and the many
breeds of our domestic animals introduced into S. America, have all been
lost and absorbed in a mongrel race. It is probably owing to the freedom of
crossing, that, in uncivilised countries, where inclosures do not exist, we
seldom meet with more than one race of a species: it is only in enclosed
countries, where the inhabitants do not migrate, and have conveniences for
separating the several kinds of domestic animals, that we meet with a
multitude of races. Even in civilised countries, want of care for a few years
has been found to destroy the good results of far longer periods of selection
and separation.
This power of crossing will affect the races of all terrestrial animals; for
all terrestrial animals require for their reproduction the union of two
individuals. Amongst plants, races will not cross and blend together with so
much freedom as in terrestrial animals; but this crossing takes place through
various curious contrivances to a surprising extent. In fact such
contrivances exist in so very many hermaphrodite flowers by which an
occasional cross may take place, that I cannot avoid suspecting (with Mr
Knight) that the reproductive action requires, at intervals, the concurrence
of distinct individuals{204}. Most breeders of plants and animals are firmly

convinced that benefit is derived from an occasional cross, not with another
race, but with another family of the same race; and that, on the other hand,
injurious consequences follow from long-continued close interbreeding in
the same family. Of marine animals, many more, than was till lately
believed, have their sexes on separate individuals; and where they are
hermaphrodite, there seems very generally to be means through the water of
one individual occasionally impregnating another: if individual animals can
singly propagate themselves for perpetuity, it is unaccountable that no
terrestrial animal, where the means of observation are more obvious, should
be in this predicament of singly perpetuating its kind. I conclude, then, that
races of most animals and plants, when unconfined in the same country,
would tend to blend together.

Whether our domestic races have descended from one or more
wild stocks.
Several naturalists, of whom Pallas{205} regarding animals, and
Humboldt regarding certain plants, were the first, believe that the breeds of
many of our domestic animals such as of the horse, pig, dog, sheep, pigeon,
and poultry, and of our plants have descended from more than one
aboriginal form. They leave it doubtful, whether such forms are to be
considered wild races, or true species, whose offspring are fertile when
crossed inter se. The main arguments for this view consist, firstly, of the
great difference between such breeds, as the Race-and Cart-Horse, or the
Greyhound and Bull-dog, and of our ignorance of the steps or stages
through which these could have passed from a common parent; and
secondly that in the most ancient historical periods, breeds resembling some
of those at present most different, existed in different countries. The wolves
of N. America and of Siberia are thought to be different species; and it has
been remarked that the dogs belonging to the savages in these two countries
resemble the wolves of the same country; and therefore that they have
probably descended from two different wild stocks. In the same manner,
these naturalists believe that the horse of Arabia and of Europe have
probably descended from two wild stocks both apparently now extinct. I do
not think the assumed fertility of these wild stocks any very great difficulty
on this view; for although in animals the offspring of most cross-bred
species are infertile, it is not always remembered that the experiment is very

seldom fairly tried, except when two near species both breed freely (which
does not readily happen, as we shall hereafter see) when under the
dominion of man. Moreover in the case of the China{206} and common
goose, the canary and siskin, the hybrids breed freely; in other cases the
offspring from hybrids crossed with either pure parent are fertile, as is
practically taken advantage of with the yak and cow; as far as the analogy
of plants serves, it is impossible to deny that some species are quite fertile
inter se; but to this subject we shall recur.
On the other hand, the upholders of the view that the several breeds of
dogs, horses, &c., &c., have descended each from one stock, may aver that
their view removes all difficulty about fertility, and that the main argument
from the high antiquity of different breeds, somewhat similar to the present
breeds, is worth little without knowing the date of the domestication of such
animals, which is far from being the case. They may also with more weight
aver that, knowing that organic beings under domestication do vary in some
degree, the argument from the great difference between certain breeds is
worth nothing, without we know the limits of variation during a long course
of time, which is far from the case. They may argue that almost every
county in England, and in many districts of other countries, for instance in
India, there are slightly different breeds of the domestic animals; and that it
is opposed to all that we know of the distribution of wild animals to
suppose that these have descended from so many different wild races or
species: if so, they may argue, is it not probable that countries quite separate
and exposed to different climates would have breeds not slightly, but
considerably, different? Taking the most favourable case, on both sides,
namely that of the dog; they might urge that such breeds as the bull-dog and
turnspit have been reared by man, from the ascertained fact that strictly
analogous breeds (namely the Niata ox and Ancon sheep) in other
quadrupeds have thus originated. Again they may say, seeing what training
and careful selection has effected for the greyhound, and seeing how
absolutely unfit the Italian greyhound is to maintain itself in a state of
nature, is it not probable that at least all greyhounds,—from the rough
deerhound, the smooth Persian, the common English, to the Italian,—have
descended from one stock{207}? If so, is it so improbable that the deerhound
and long-legged shepherd dog have so descended? If we admit this, and

give up the bull-dog, we can hardly dispute the probable common descent
of the other breeds.
The evidence is so conjectural and balanced on both sides that at present
I conceive that no one can decide: for my own part, I lean to the probability
of most of our domestic animals having descended from more than one wild
stock; though from the arguments last advanced and from reflecting on the
slow though inevitable effect of different races of mankind, under different
circumstances, saving the lives of and therefore selecting the individuals
most useful to them, I cannot doubt but that one class of naturalists have
much overrated the probable number of the aboriginal wild stocks. As far as
we admit the difference of our races «to be» due to the differences of their
original stocks, so much must we give up of the amount of variation
produced under domestication. But this appears to me unimportant, for we
certainly know in some few cases, for instance in the Dahlia, and potato,
and rabbit, that a great number of varieties have proceeded from one stock;
and, in many of our domestic races, we know that man, by slowly selecting
and by taking advantage of sudden sports, has considerably modified old
races and produced new ones. Whether we consider our races as the
descendants of one or several wild stocks, we are in far the greater number
of cases equally ignorant what these stocks were.

Limits to Variation in degree and kind.
Man’s power in making races deends, in the first instance, on the stock
on which he works being variable; but his labours are modified and limited,
as we have seen, by the direct effects of the external conditions,—by the
deficient or imperfect hereditariness of new peculiarities,—and by the
tendency to continual variation and especially to reversion to ancestral
forms. If the stock is not variable under domestication, of course he can do
nothing; and it appears that species differ considerably in this tendency to
variation, in the same way as even sub-varieties from the same variety
differ greatly in this respect, and transmit to their offspring this difference in
tendency. Whether the absence of a tendency to vary is an unalterable
quality in certain species, or depends on some deficient condition of the
particular state of domestication to which they are exposed, there is no
evidence. When the organization is rendered variable, or plastic, as I have
expressed it, under domestication, different parts of the frame vary more or

less in different species: thus in the breeds of cattle it has been remarked
that the horns are the most constant or least variable character, for these
often remain constant, whilst the colour, size, proportions of the body,
tendency to fatten &c., vary; in sheep, I believe, the horns are much more
variable. As a general rule the less important parts of the organization seem
to vary most, but I think there is sufficient evidence that every part
occasionally varies in a slight degree. Even when man has the primary
requisite variability he is necessarily checked by the health and life of the
stock he is working on: thus he has already made pigeons with such small
beaks that they can hardly eat and will not rear their own young; he has
made families of sheep with so strong a tendency to early maturity and to
fatten, that in certain pastures they cannot live from their extreme liability
to inflammation; he has made (i.e. selected) sub-varieties of plants with a
tendency to such early growth that they are frequently killed by the spring
frosts; he has made a breed of cows having calves with such large hinder
quarters that they are born with great difficulty, often to the death of their
mothers{208}; the breeders were compelled to remedy this by the selection of
a breeding stock with smaller hinder quarters; in such a case, however, it is
possible by long patience and great loss, a remedy might have been found
in selecting cows capable of giving birth to calves with large hinder
quarters, for in human kind there «are» no doubt hereditary bad and good
confinements. Besides the limits already specified, there can be little doubt
that the variation of different parts of the frame are connected together by
many laws{209}: thus the two sides of the body, in health and disease, seem
almost always to vary together: it has been asserted by breeders that if the
head is much elongated, the bones of the extremities will likewise be so; in
seedling-apples large leaves and fruit generally go together, and serve the
horticulturalist as some guide in his selection; we can here see the reason,
as the fruit is only a metamorphosed leaf. In animals the teeth and hair seem
connected, for the hairless Chinese dog is almost toothless. Breeders
believe that one part of the frame or function being increased causes other
parts to decrease: they dislike great horns and great bones as so much flesh
lost; in hornless breeds of cattle certain bones of the head become more
developed: it is said that fat accumulating in one part checks its
accumulation in another, and likewise checks the action of the udder. The
whole organization is so connected that it is probable there are many
conditions determining the variation of each part, and causing other parts to

vary with it; and man in making new races must be limited and ruled by all
such laws.

In what consists Domestication.
In this chapter we have treated of variation under domestication, and it
now remains to consider in what does this power of domestication
consist{210}, a subject of considerable difficulty. Observing that organic
beings of almost every class, in all climates, countries, and times, have
varied when long bred under domestication, we must conclude that the
influence is of some very general nature{211}. Mr Knight alone, as far as I
know, has tried to define it; he believes it consists of an excess of food,
together with transport to a more genial climate, or protection from its
severities. I think we cannot admit this latter proposition, for we know how
many vegetable products, aborigines of this country, here vary, when
cultivated without any protection from the weather; and some of our
variable trees, as apricots, peaches, have undoubtedly been derived from a
more genial climate. There appears to be much more truth in the doctrine of
excess of food being the cause, though I much doubt whether this is the sole
cause, although it may well be requisite for the kind of variation desired by
man, namely increase of size and vigour. No doubt horticulturalists, when
they wish to raise new seedlings, often pluck off all the flower-buds, except
a few, or remove the whole during one season, so that a great stock of
nutriment may be thrown into the flowers which are to seed. When plants
are transported from high-lands, forests, marshes, heaths, into our gardens
and greenhouses, there must be a considerable change of food, but it would
be hard to prove that there was in every case an excess of the kind proper to
the plant. If it be an excess of food, compared with that which the being
obtained in its natural state{212}, the effects continue for an improbably long
time; during how many ages has wheat been cultivated, and cattle and sheep
reclaimed, and we cannot suppose their amount of food has gone on
increasing, nevertheless these are amongst the most variable of our
domestic productions. It has been remarked (Marshall) that some of the
most highly kept breeds of sheep and cattle are truer or less variable than
the straggling animals of the poor, which subsist on commons, and pick up
a bare subsistence{213}. In the case of forest-trees raised in nurseries, which
vary more than the same trees do in their aboriginal forests, the cause would
seem simply to lie in their not having to struggle against other trees and

weeds, which in their natural state doubtless would limit the conditions of
their existence. It appears to me that the power of domestication resolves
itself into the accumulated effects of a change of all or some of the natural
conditions of the life of the species, often associated with excess of food.
These conditions moreover, I may add, can seldom remain, owing to the
mutability of the affairs, habits, migrations, and knowledge of man, for very
long periods the same. I am the more inclined to come to this conclusion
from finding, as we shall hereafter show, that changes of the natural
conditions of existence seem peculiarly to affect the action of the
reproductive system{214}. As we see that hybrids and mongrels, after the first
generation, are apt to vary much, we may at least conclude that variability
does not altogether depend on excess of food.
After these views, it may be asked how it comes that certain animals
and plants, which have been domesticated for a considerable length of time,
and transported from very different conditions of existence, have not varied
much, or scarcely at all; for instance, the ass, peacock, guinea-fowl,
asparagus, Jerusalem artichoke{215}. I have already said that probably
different species, like different sub-varieties, possess different degrees of
tendency to vary; but I am inclined to attribute in these cases the want of
numerous races less to want of variability than to selection not having been
practised on them. No one will take the pains to select without some
corresponding object, either of use or amusement; the individuals raised
must be tolerably numerous, and not so precious, but that he may freely
destroy those not answering to his wishes. If guinea-fowls or peacocks{216}
became “fancy” birds, I cannot doubt that after some generations several
breeds would be raised. Asses have not been worked on from mere neglect;
but they differ in some degree in different countries. The insensible
selection, due to different races of mankind preserving those individuals
most useful to them in their different circumstances, will apply only to the
oldest and most widely domesticated animals. In the case of plants, we must
put entirely out of the case those exclusively (or almost so) propagated by
cuttings, layers or tubers, such as the Jerusalem artichoke and laurel; and if
we put on one side plants of little ornament or use, and those which are
used at so early a period of their growth that no especial characters signify,
as asparagus{217} and seakale, I can think of none long cultivated which have
not varied. In no case ought we to expect to find as much variation in a race

when it alone has been formed, as when several have been formed, for their
crossing and recrossing will greatly increase their variability.

Summary of first Chapter.
To sum up this chapter. Races are made under domestication: 1st, by the
direct effects of the external conditions to which the species is exposed:
2nd, by the indirect effects of the exposure to new conditions, often aided
by excess of food, rendering the organization plastic, and by man’s
selecting and separately breeding certain individuals, or introducing to his
stock selected males, or often preserving with care the life of the individuals
best adapted to his purposes: 3rd, by crossing and recrossing races already
made, and selecting their offspring. After some generations man may relax
his care in selection: for the tendency to vary and to revert to ancestral
forms will decrease, so that he will have only occasionally to remove or
destroy one of the yearly offspring which departs from its type. Ultimately,
with a large stock, the effects of free crossing would keep, even without this
care, his breed true. By these means man can produce infinitely numerous
races, curiously adapted to ends, both most important and most frivolous; at
the same time that the effects of the surrounding conditions, the laws of
inheritance, of growth, and of variation, will modify and limit his labours.

CHAPTER II
on the variation of organic beings in a wild
state; on the natural means of selection; and on
the comparison of domestic races and true
species

Having treated of variation under domestication, we now come to it in a
state of nature.
Most organic beings in a state of nature vary exceedingly little{218}: I put
out of the case variations (as stunted plants &c., and sea-shells in brackish
water{219}) which are directly the effect of external agencies and which we
do not know are in the breed{220}, or are hereditary. The amount of
hereditary variation is very difficult to ascertain, because naturalists (partly
from the want of knowledge, and partly from the inherent difficulty of the
subject) do not all agree whether certain forms are species or races{221}.
Some strongly marked races of plants, comparable with the decided sports
of horticulturalists, undoubtedly exist in a state of nature, as is actually
known by experiment, for instance in the primrose and cowslip{222}, in two
so-called species of dandelion, in two of foxglove{223}, and I believe in some
pines. Lamarck has observed that, as long as we confine our attention to one
limited country, there is seldom much difficulty in deciding what forms to
call species and what varieties; and that it is when collections flow in from
all parts of the world that naturalists often feel at a loss to decide the limit
of variation. Undoubtedly so it is, yet amongst British plants (and I may add
land shells), which are probably better known than any in the world, the
best naturalists differ very greatly in the relative proportions of what they
call species and what varieties. In many genera of insects, and shells, and
plants, it seems almost hopeless to establish which are which. In the higher
classes there are less doubts; though we find considerable difficulty in
ascertaining what deserve to be called species amongst foxes and wolves,
and in some birds, for instance in the case of the white barn-owl. When
specimens are brought from different parts of the world, how often do

naturalists dispute this same question, as I found with respect to the birds
brought from the Galapagos islands. Yarrell has remarked that the
individuals of the same undoubted species of birds, from Europe and N.
America, usually present slight, indefinable though perceptible differences.
The recognition indeed of one animal by another of its kind seems to imply
some difference. The disposition of wild animals undoubtedly differs. The
variation, such as it is, chiefly affects the same parts in wild organisms as in
domestic breeds; for instance, the size, colour, and the external and less
important parts. In many species the variability of certain organs or qualities
is even stated as one of the specific characters: thus, in plants, colour, size,
hairiness, the number of the stamens and pistils, and even their presence,
the form of the leaves; the size and form of the mandibles of the males of
some insects; the length and curvature of the beak in some birds (as in
Opetiorynchus) are variable characters in some species and quite fixed in
others. I do not perceive that any just distinction can be drawn between this
recognised variability of certain parts in many species and the more general
variability of the whole frame in domestic races.
Although the amount of variation be exceedingly small in most organic
beings in a state of nature, and probably quite wanting (as far as our senses
serve) in the majority of cases; yet considering how many animals and
plants, taken by mankind from different quarters of the world for the most
diverse purposes, have varied under domestication in every country and in
every age, I think we may safely conclude that all organic beings with few
exceptions, if capable of being domesticated and bred for long periods,
would vary. Domestication seems to resolve itself into a change from the
natural conditions of the species [generally perhaps including an increase of
food]; if this be so, organisms in a state of nature must occasionally, in the
course of ages, be exposed to analogous influences; for geology clearly
shows that many places must, in the course of time, become exposed to the
widest range of climatic and other influences; and if such places be isolated,
so that new and better adapted organic beings cannot freely emigrate, the
old inhabitants will be exposed to new influences, probably far more varied,
than man applies under the form of domestication. Although every species
no doubt will soon breed up to the full number which the country will
support, yet it is easy to conceive that, on an average, some species may
receive an increase of food; for the times of dearth may be short, yet enough

to kill, and recurrent only at long intervals. All such changes of conditions
from geological causes would be exceedingly slow; what effect the
slowness might have we are ignorant; under domestication it appears that
the effects of change of conditions accumulate, and then break out.
Whatever might be the result of these slow geological changes, we may feel
sure, from the means of dissemination common in a lesser or greater degree
to every organism taken conjointly with the changes of geology, which are
steadily (and sometimes suddenly, as when an isthmus at last separates) in
progress, that occasionally organisms must suddenly be introduced into new
regions, where, if the conditions of existence are not so foreign as to cause
its extermination, it will often be propagated under circumstances still more
closely analogous to those of domestication; and therefore we expect will
evince a tendency to vary. It appears to me quite inexplicable if this has
never happened; but it can happen very rarely. Let us then suppose that an
organism by some chance (which might be hardly repeated in 1000 years)
arrives at a modern volcanic island in process of formation and not fully
stocked with the most appropriate organisms; the new organism might
readily gain a footing, although the external conditions were considerably
different from its native ones. The effect of this we might expect would
influence in some small degree the size, colour, nature of covering &c., and
from inexplicable influences even special parts and organs of the body. But
we might further (and «this» is far more important) expect that the
reproductive system would be affected, as under domesticity, and the
structure of the offspring rendered in some degree plastic. Hence almost
every part of the body would tend to vary from the typical form in slight
degrees, and in no determinate way, and therefore without selection the free
crossing of these small variations (together with the tendency to reversion
to the original form) would constantly be counteracting this unsettling effect
of the extraneous conditions on the reproductive system. Such, I conceive,
would be the unimportant result without selection. And here I must observe
that the foregoing remarks are equally applicable to that small and admitted
amount of variation which has been observed in some organisms in a state
of nature; as well as to the above hypothetical variation consequent on
changes of condition.
Let us now suppose a Being{224} with penetration sufficient to perceive
differences in the outer and innermost organization quite imperceptible to

man, and with forethought extending over future centuries to watch with
unerring care and select for any object the offspring of an organism
produced under the foregoing circumstances; I can see no conceivable
reason why he could not form a new race (or several were he to separate the
stock of the original organism and work on several islands) adapted to new
ends. As we assume his discrimination, and his forethought, and his
steadiness of object, to be incomparably greater that those qualities in man,
so we may suppose the beauty and complications of the adaptations of the
new races and their differences from the original stock to be greater than in
the domestic races produced by man’s agency: the ground-work of his
labours we may aid by supposing that the external conditions of the
volcanic island, from its continued emergence and the occasional
introduction of new immigrants, vary; and thus to act on the reproductive
system of the organism, on which he is at work, and so keep its organization
somewhat plastic. With time enough, such a Being might rationally
(without some unknown law opposed him) aim at almost any result.
For instance, let this imaginary Being wish, from seeing a plant growing
on the decaying matter in a forest and choked by other plants, to give it
power of growing on the rotten stems of trees, he would commence
selecting every seedling whose berries were in the smallest degree more
attractive to tree-frequenting birds, so as to cause a proper dissemination of
the seeds, and at the same time he would select those plants which had in
the slightest degree more and more power of drawing nutriment from rotten
wood; and he would destroy all other seedlings with less of this power. He
might thus, in the course of century after century, hope to make the plant by
degrees grow on rotten wood, even high up on trees, wherever birds
dropped the non-digested seeds. He might then, if the organization of the
plant was plastic, attempt by continued selection of chance seedlings to
make it grow on less and less rotten wood, till it would grow on sound
wood{225}. Supposing again, during these changes the plant failed to seed
quite freely from non-impregnation, he might begin selecting seedlings with
a little sweeter «or» differently tasted honey or pollen, to tempt insects to
visit the flowers regularly: having effected this, he might wish, if it profited
the plant, to render abortive the stamens and pistils in different flowers,
which he could do by continued selection. By such steps he might aim at
making a plant as wonderfully related to other organic beings as is the

mistletoe, whose existence absolutely depends on certain insects for
impregnation, certain birds for transportal, and certain trees for growth.
Furthermore, if the insect which had been induced regularly to visit this
hypothetical plant profited much by it, our same Being might wish by
selection to modify by gradual selection the insect’s structure, so as to
facilitate its obtaining the honey or pollen: in this manner he might adapt
the insect (always presupposing its organization to be in some degree
plastic) to the flower, and the impregnation of the flower to the insect; as is
the case with many bees and many plants.
Seeing what blind capricious man has actually effected by selection
during the few last years, and what in a ruder state he has probably effected
without any systematic plan during the last few thousand years, he will be a
bold person who will positively put limits to what the supposed Being could
effect during whole geological periods. In accordance with the plan by
which this universe seems governed by the Creator, let us consider whether
there exists any secondary means in the economy of nature by which the
process of selection could go on adapting, nicely and wonderfully,
organisms, if in ever so small a degree plastic, to diverse ends. I believe
such secondary means do exist{226}.

Natural means of Selection{227}.
De Candolle, in an eloquent passage, has declared that all nature is at
war, one organism with another, or with external nature. Seeing the
contented face of nature, this may at first be well doubted; but reflection
will inevitably prove it is too true. The war, however, is not constant, but
only recurrent in a slight degree at short periods and more severely at
occasional more distant periods; and hence its effects are easily overlooked.
It is the doctrine of Malthus applied in most cases with ten-fold force. As in
every climate there are seasons for each of its inhabitants of greater and less
abundance, so all annually breed; and the moral restraint, which in some
small degree checks the increase of mankind, is entirely lost. Even slow-
breeding mankind has doubled in 25 years{228}, and if he could increase his
food with greater ease, he would double in less time. But for animals,
without artificial means, on an average the amount of food for each species
must be constant; whereas the increase of all organisms tends to be
geometrical, and in a vast majority of cases at an enormous ratio. Suppose

in a certain spot there are eight pairs of [robins] birds, and that only four
pairs of them annually (including double hatches) rear only four young; and
that these go on rearing their young at the same rate: then at the end of
seven years (a short life, excluding violent deaths, for any birds) there will
be 2048 robins, instead of the original sixteen; as this increase is quite
impossible, so we must conclude either that robins do not rear nearly half
their young or that the average life of a robin when reared is from accident
not nearly seven years. Both checks probably concur. The same kind of
calculation applied to all vegetables and animals produces results either
more or less striking, but in scarcely a single instance less striking than in
man{229}.
Many practical illustrations of this rapid tendency to increase are on
record, namely during peculiar seasons, in the extraordinary increase of
certain animals, for instance during the years 1826 to 1828, in La Plata,
when from drought, some millions of cattle perished, the whole country
swarmed with innumerable mice: now I think it cannot be doubted that
during the breeding season all the mice (with the exception of a few males
or females in excess) ordinarily pair; and therefore that this astounding
increase during three years must be attributed to a greater than usual
number surviving the first year, and then breeding, and so on, till the third
year, when their numbers were brought down to their usual limits on the
return of wet weather. Where man has introduced plants and animals into a
new country favourable to them, there are many accounts in how
surprisingly few years the whole country has become stocked with them.
This increase would necessarily stop as soon as the country was fully
stocked; and yet we have every reason to believe from what is known of
wild animals that all would pair in the spring. In the majority of cases it is
most difficult to imagine where the check falls, generally no doubt on the
seeds, eggs, and young; but when we remember how impossible even in
mankind (so much better known than any other animal) it is to infer from
repeated casual observations what the average of life is, or to discover how
different the percentage of deaths to the births in different countries, we
ought to feel no legitimate surprise at not seeing where the check falls in
animals and plants. It should always be remembered that in most cases the
checks are yearly recurrent in a small regular degree, and in an extreme
degree during occasionally unusually cold, hot, dry, or wet years, according

to the constitution of the being in question. Lighten any check in the
smallest degree, and the geometrical power of increase in every organism
will instantly increase the average numbers of the favoured species. Nature
may be compared to a surface, on which rest ten thousand sharp wedges
touching each other and driven inwards by incessant blows{230}. Fully to
realise these views much reflection is requisite; Malthus on man should be
studied; and all such cases as those of the mice in La Plata, of the cattle and
horses when first turned out in S. America, of the robins by our calculation,
&c., should be well considered: reflect on the enormous multiplying power
inherent and annually in action in all animals; reflect on the countless seeds
scattered by a hundred ingenious contrivances, year after year, over the
whole face of the land; and yet we have every reason to suppose that the
average percentage of every one of the inhabitants of a country will
ordinarily remain constant. Finally, let it be borne in mind that this average
number of individuals (the external conditions remaining the same) in each
country is kept up by recurrent struggles against other species or against
external nature (as on the borders of the arctic regions{231}, where the cold
checks life); and that ordinarily each individual of each species holds its
place, either by its own struggle and capacity of acquiring nourishment in
some period (from the egg upwards) of its life, or by the struggle of its
parents (in short lived organisms, when the main check occurs at long
intervals) against and compared with other individuals of the same or
different species.
But let the external conditions of a country change; if in a small degree,
the relative proportions of the inhabitants will in most cases simply be
slightly changed; but let the number of inhabitants be small, as in an
island{232}, and free access to it from other countries be circumscribed; and
let the change of condition continue progressing (forming new stations); in
such case the original inhabitants must cease to be so perfectly adapted to
the changed conditions as they originally were. It has been shown that
probably such changes of external conditions would, from acting on the
reproductive system, cause the organization of the beings most affected to
become, as under domestication, plastic. Now can it be doubted from the
struggle each individual (or its parents) has to obtain subsistence that any
minute variation in structure, habits, or instincts, adapting that individual
better to the new conditions, would tell upon its vigour and health? In the

struggle it would have a better chance of surviving, and those of its
offspring which inherited the variation, let it be ever so slight, would have a
better chance to survive. Yearly more are bred than can survive; the
smallest grain in the balance, in the long run, must tell on which death shall
fall, and which shall survive{233}. Let this work of selection, on the one
hand, and death on the other, go on for a thousand generations; who would
pretend to affirm that it would produce no effect, when we remember what
in a few years Bakewell effected in cattle and Western in sheep, by this
identical principle of selection.
To give an imaginary example, from changes in progress on an island,
let the organization{234} of a canine animal become slightly plastic, which
animal preyed chiefly on rabbits, but sometimes on hares; let these same
changes cause the number of rabbits very slowly to decrease and the
number of hares to increase; the effect of this would be that the fox or dog
would be driven to try to catch more hares, and his numbers would tend to
decrease; his organization, however, being slightly plastic, those individuals
with the lightest forms, longest limbs, and best eye-sight (though perhaps
with less cunning or scent) would be slightly favoured, let the difference be
ever so small, and would tend to live longer and to survive during that time
of the year when food was shortest; they would also rear more young,
which young would tend to inherit these slight peculiarities. The less fleet
ones would be rigidly destroyed. I can see no more reason to doubt but that
these causes in a thousand generations would produce a marked effect, and
adapt the form of the fox to catching hares instead of rabbits, than that
greyhounds can be improved by selection and careful breeding. So would it
be with plants under similar circumstances; if the number of individuals of
a species with plumed seeds could be increased by greater powers of
dissemination within its own area (that is if the check to increase fell chiefly
on the seeds), those seeds which were provided with ever so little more
down, or with a plume placed so as to be slightly more acted on by the
winds, would in the long run tend to be most disseminated; and hence a
greater number of seeds thus formed would germinate, and would tend to
produce plants inheriting this slightly better adapted down.
Besides this natural means of selection, by which those individuals are
preserved, whether in their egg or seed or in their mature state, which are
best adapted to the place they fill in nature, there is a second agency at work

in most bisexual animals tending to produce the same effect, namely the
struggle of the males for the females. These struggles are generally decided
by the law of battle; but in the case of birds, apparently, by the charms of
their song{235}, by their beauty or their power of courtship, as in the dancing
rock-thrush of Guiana. Even in the animals which pair there seems to be an
excess of males which would aid in causing a struggle: in the polygamous
animals{236}, however, as in deer, oxen, poultry, we might expect there
would be severest struggle: is it not in the polygamous animals that the
males are best formed for mutual war? The most vigorous males, implying
perfect adaptation, must generally gain the victory in their several contests.
This kind of selection, however, is less rigorous than the other; it does not
require the death of the less successful, but gives to them fewer
descendants. This struggle falls, moreover, at a time of year when food is
generally abundant, and perhaps the effect chiefly produced would be the
alteration of sexual characters, and the selection of individual forms, no
way related to their power of obtaining food, or of defending themselves
from their natural enemies, but of fighting one with another. This natural
struggle amongst the males may be compared in effect, but in a less degree,
to that produced by those agriculturalists who pay less attention to the
careful selection of all the young animals which they breed and more to the
occasional use of a choice male{237}.

Differences between “Races” and “Species”:—first, in their
trueness or variability.
Races{238} produced by these natural means of selection{239} we may
expect would differ in some respects from those produced by man. Man
selects chiefly by the eye, and is not able to perceive the course of every
vessel and nerve, or the form of the bones, or whether the internal structure
corresponds to the outside shape. He{240} is unable to select shades of
constitutional differences, and by the protection he affords and his
endeavours to keep his property alive, in whatever country he lives, he
checks, as much as lies in his power, the selecting action of nature, which
will, however, go on to a lesser degree with all living things, even if their
length of life is not determined by their own powers of endurance. He has
bad judgment, is capricious, he does not, or his successors do not, wish to
select for the same exact end for hundreds of generations. He cannot always

suit the selected form to the properest conditions; nor does he keep those
conditions uniform: he selects that which is useful to him, not that best
adapted to those conditions in which each variety is placed by him: he
selects a small dog, but feeds it highly; he selects a long-backed dog, but
does not exercise it in any peculiar manner, at least not during every
generation. He seldom allows the most vigorous males to struggle for
themselves and propagate, but picks out such as he possesses, or such as he
prefers, and not necessarily those best adapted to the existing conditions.
Every agriculturalist and breeder knows how difficult it is to prevent an
occasional cross with another breed. He often grudges to destroy an
individual which departs considerably from the required type. He often
begins his selection by a form or sport considerably departing from the
parent form. Very differently does the natural law of selection act; the
varieties selected differ only slightly from the parent forms{241}; the
conditions are constant for long periods and change slowly; rarely can there
be a cross; the selection is rigid and unfailing, and continued through many
generations; a selection can never be made without the form be better
adapted to the conditions than the parent form; the selecting power goes on
without caprice, and steadily for thousands of years adapting the form to
these conditions. The selecting power is not deceived by external
appearances, it tries the being during its whole life; and if less well «?»
adapted than its congeners, without fail it is destroyed; every part of its
structure is thus scrutinised and proved good towards the place in nature
which it occupies.
We have every reason to believe that in proportion to the number of
generations that a domestic race is kept free from crosses, and to the care
employed in continued steady selection with one end in view, and to the
care in not placing the variety in conditions unsuited to it; in such
proportion does the new race become “true” or subject to little variation{242}.
How incomparably “truer” then would a race produced by the above rigid,
steady, natural means of selection, excellently trained and perfectly adapted
to its conditions, free from stains of blood or crosses, and continued during
thousands of years, be compared with one produced by the feeble,
capricious, misdirected and ill-adapted selection of man. Those races of
domestic animals produced by savages, partly by the inevitable conditions
of their life, and partly unintentionally by their greater care of the

individuals most valuable to them, would probably approach closest to the
character of a species; and I believe this is the case. Now the characteristic
mark of a species, next, if not equal in importance to its sterility when
crossed with another species, and indeed almost the only other character
(without we beg the question and affirm the essence of a species, is its not
having descended from a parent common to any other form), is the
similarity of the individuals composing the species, or in the language of
agriculturalists their “trueness.”

Difference between “Races” and “Species” in fertility when
crossed.
The sterility of species, or of their offspring, when crossed has,
however, received more attention than the uniformity in character of the
individuals composing the species. It is exceedingly natural that such
sterility{243} should have been long thought the certain characteristic of
species. For it is obvious that if the allied different forms which we meet
with in the same country could cross together, instead of finding a number
of distinct species, we should have a confused and blending series. The fact
however of a perfect gradation in the degree of sterility between species,
and the circumstance of some species most closely allied (for instance many
species of crocus and European heaths) refusing to breed together, whereas
other species, widely different, and even belonging to distinct genera, as the
fowl and the peacock, pheasant and grouse{244}, Azalea and Rhododendron,
Thuja and Juniperus, breeding together ought to have caused a doubt
whether the sterility did not depend on other causes, distinct from a law,
coincident with their creation. I may here remark that the fact whether one
species will or will not breed with another is far less important than the
sterility of the offspring when produced; for even some domestic races
differ so greatly in size (as the great stag-greyhound and lap-dog, or cart-
horse and Burmese ponies) that union is nearly impossible; and what is less
generally known is, that in plants Kölreuter has shown by hundreds of
experiments that the pollen of one species will fecundate the germen of
another species, whereas the pollen of this latter will never act on the
germen of the former; so that the simple fact of mutual impregnation
certainly has no relation whatever to the distinctness in creation of the two
forms. When two species are attempted to be crossed which are so distantly

allied that offspring are never produced, it has been observed in some cases
that the pollen commences its proper action by exserting its tube, and the
germen commences swelling, though soon afterwards it decays. In the next
stage in the series, hybrid offspring are produced though only rarely and
few in number, and these are absolutely sterile: then we have hybrid
offspring more numerous, and occasionally, though very rarely, breeding
with either parent, as is the case with the common mule. Again, other
hybrids, though infertile inter se, will breed quite freely with either parent,
or with a third species, and will yield offspring generally infertile, but
sometimes fertile; and these latter again will breed with either parent, or
with a third or fourth species: thus Kölreuter blended together many forms.
Lastly it is now admitted by those botanists who have longest contended
against the admission, that in certain families the hybrid offspring of many
of the species are sometimes perfectly fertile in the first generation when
bred together: indeed in some few cases Mr Herbert{245} found that the
hybrids were decidedly more fertile than either of their pure parents. There
is no way to escape from the admission that the hybrids from some species
of plants are fertile, except by declaring that no form shall be considered as
a species, if it produces with another species fertile offspring: but this is
begging the question{246}. It has often been stated that different species of
animals have a sexual repugnance towards each other; I can find no
evidence of this; it appears as if they merely did not excite each others
passions. I do not believe that in this respect there is any essential
distinction between animals and plants; and in the latter there cannot be a
feeling of repugnance.

Causes of Sterility in Hybrids.
The difference in nature between species which causes the greater or
lesser degree of sterility in their offspring appears, according to Herbert and
Kölreuter, to be connected much less with external form, size, or structure,
than with constitutional peculiarities; by which is meant their adaptation to
different climates, food and situation, &c.: these peculiarities of constitution
probably affect the entire frame, and no one part in particular{247}.
From the foregoing facts I think we must admit that there exists a
perfect gradation in fertility between species which when crossed are quite
fertile (as in Rhododendron, Calceolaria, &c.), and indeed in an

extraordinary degree fertile (as in Crinum), and those species which never
produce offspring, but which by certain effects (as the exsertion of the
pollen-tube) evince their alliance. Hence, I conceive, we must give up
sterility, although undoubtedly in a lesser or greater degree of very frequent
occurrence, as an unfailing mark by which species can be distinguished
from races, i.e. from those forms which have descended from a common
stock.

Infertility from causes distinct from hybridisation.
Let us see whether there are any analogous facts which will throw any
light on this subject, and will tend to explain why the offspring of certain
species, when crossed, should be sterile, and not others, without requiring a
distinct law connected with their creation to that effect. Great numbers,
probably a large majority of animals when caught by man and removed
from their natural conditions, although taken very young, rendered quite
tame, living to a good old age, and apparently quite healthy, seem incapable
under these circumstances of breeding{248}. I do not refer to animals kept in
menageries, such as at the Zoological Gardens, many of which, however,
appear healthy and live long and unite but do not produce; but to animals
caught and left partly at liberty in their native country. Rengger{249}
enumerates several caught young and rendered tame, which he kept in
Paraguay, and which would not breed: the hunting leopard or cheetah and
elephant offer other instances; as do bears in Europe, and the 25 species of
hawks, belonging to different genera, thousands of which have been kept
for hawking and have lived for long periods in perfect vigour. When the
expense and trouble of procuring a succession of young animals in a wild
state be borne in mind, one may feel sure that no trouble has been spared in
endeavours to make them breed. So clearly marked is this difference in
different kinds of animals, when captured by man, that St Hilaire makes two
great classes of animals useful to man:—the tame, which will not breed,
and the domestic which will breed in domestication. From certain singular
facts we might have supposed that the non-breeding of animals was owing
to some perversion of instinct. But we meet with exactly the same class of
facts in plants: I do not refer to the large number of cases where the climate
does not permit the seed or fruit to ripen, but where the flowers do not
“set,” owing to some imperfection of the ovule or pollen. The latter, which
alone can be distinctly examined, is often manifestly imperfect, as any one

with a microscope can observe by comparing the pollen of the Persian and
Chinese lilacs{250} with the common lilac; the two former species (I may
add) are equally sterile in Italy as in this country. Many of the American
bog plants here produce little or no pollen, whilst the Indian species of the
same genera freely produce it. Lindley observes that sterility is the bane of
the horticulturist{251}: Linnæus has remarked on the sterility of nearly all
alpine flowers when cultivated in a lowland district{252}. Perhaps the
immense class of double flowers chiefly owe their structure to an excess of
food acting on parts rendered slightly sterile and less capable of performing
their true function, and therefore liable to be rendered monstrous, which
monstrosity, like any other disease, is inherited and rendered common. So
far from domestication being in itself unfavourable to fertility, it is well
known that when an organism is once capable of submission to such
conditions «its» fertility is increased{253} beyond the natural limit. According
to agriculturists, slight changes of conditions, that is of food or habitation,
and likewise crosses with races slightly different, increase the vigour and
probably the fertility of their offspring. It would appear also that even a
great change of condition, for instance, transportal from temperate countries
to India, in many cases does not in the least affect fertility, although it does
health and length of life and the period of maturity. When sterility is
induced by domestication it is of the same kind, and varies in degree,
exactly as with hybrids: for be it remembered that the most sterile hybrid is
no way monstrous; its organs are perfect, but they do not act, and minute
microscopical investigations show that they are in the same state as those of
pure species in the intervals of the breeding season. The defective pollen in
the cases above alluded to precisely resembles that of hybrids. The
occasional breeding of hybrids, as of the common mule, may be aptly
compared to the most rare but occasional reproduction of elephants in
captivity. The cause of many exotic Geraniums producing (although in
vigorous health) imperfect pollen seems to be connected with the period
when water is given them{254}; but in the far greater majority of cases we
cannot form any conjecture on what exact cause the sterility of organisms
taken from their natural conditions depends. Why, for instance, the cheetah
will not breed whilst the common cat and ferret (the latter generally kept
shut up in a small box) do,—why the elephant will not whilst the pig will
abundantly—why the partridge and grouse in their own country will not,
whilst several species of pheasants, the guinea-fowl from the deserts of

Africa and the peacock from the jungles of India, will. We must, however,
feel convinced that it depends on some constitutional peculiarities in these
beings not suited to their new condition; though not necessarily causing an
ill state of health. Ought we then to wonder much that those hybrids which
have been produced by the crossing of species with different constitutional
tendencies (which tendencies we know to be eminently inheritable) should
be sterile: it does not seem improbable that the cross from an alpine and
lowland plant should have its constitutional powers deranged, in nearly the
same manner as when the parent alpine plant is brought into a lowland
district. Analogy, however, is a deceitful guide, and it would be rash to
affirm, although it may appear probable, that the sterility of hybrids is due
to the constitutional peculiarities of one parent being disturbed by being
blended with those of the other parent in exactly the same manner as it is
caused in some organic beings when placed by man out of their natural
conditions{255}. Although this would be rash, it would, I think, be still rasher,
seeing that sterility is no more incidental to all cross-bred productions than
it is to all organic beings when captured by man, to assert that the sterility
of certain hybrids proved a distinct creation of their parents.
But it may be objected{256} (however little the sterility of certain hybrids
is connected with the distinct creations of species), how comes it, if species
are only races produced by natural selection, that when crossed they so
frequently produce sterile offspring, whereas in the offspring of those races
confessedly produced by the arts of man there is no one instance of sterility.
There is not much difficulty in this, for the races produced by the natural
means above explained will be slowly but steadily selected; will be adapted
to various and diverse conditions, and to these conditions they will be
rigidly confined for immense periods of time; hence we may suppose that
they would acquire different constitutional peculiarities adapted to the
stations they occupy; and on the constitutional differences between species
their sterility, according to the best authorities, depends. On the other hand
man selects by external appearance{257}; from his ignorance, and from not
having any test at least comparable in delicacy to the natural struggle for
food, continued at intervals through the life of each individual, he cannot
eliminate fine shades of constitution, dependent on invisible differences in
the fluids or solids of the body; again, from the value which he attaches to
each individual, he asserts his utmost power in contravening the natural

tendency of the most vigorous to survive. Man, moreover, especially in the
earlier ages, cannot have kept his conditions of life constant, and in later
ages his stock pure. Until man selects two varieties from the same stock,
adapted to two climates or to other different external conditions, and
confines each rigidly for one or several thousand years to such conditions,
always selecting the individuals best adapted to them, he cannot be said to
have even commenced the experiment. Moreover, the organic beings which
man has longest had under domestication have been those which were of
the greatest use to him, and one chief element of their usefulness, especially
in the earlier ages, must have been their capacity to undergo sudden
transportals into various climates, and at the same time to retain their
fertility, which in itself implies that in such respects their constitutional
peculiarities were not closely limited. If the opinion already mentioned be
correct, that most of the domestic animals in their present state have
descended from the fertile commixture of wild races or species, we have
indeed little reason now to expect infertility between any cross of stock thus
descended.
It is worthy of remark, that as many organic beings, when taken by man
out of their natural conditions, have their reproductive system «so» affected
as to be incapable of propagation, so, we saw in the first chapter, that
although organic beings when taken by man do propagate freely, their
offspring after some generations vary or sport to a degree which can only be
explained by their reproductive system being «in» some way affected.
Again, when species cross, their offspring are generally sterile; but it was
found by Kölreuter that when hybrids are capable of breeding with either
parent, or with other species, that their offspring are subject after some
generations to excessive variation{258}. Agriculturists, also, affirm that the
offspring from mongrels, after the first generation, vary much. Hence we
see that both sterility and variation in the succeeding generations are
consequent both on the removal of individual species from their natural
states and on species crossing. The connection between these facts may be
accidental, but they certainly appear to elucidate and support each other,—
on the principle of the reproductive system of all organic beings being
eminently sensitive to any disturbance, whether from removal or
commixture, in their constitutional relations to the conditions to which they
are exposed.

Points of Resemblance between “Races” and “Species{259}.”
Races and reputed species agree in some respects, although differing
from causes which, we have seen, we can in some degree understand, in the
fertility and “trueness” of their offspring. In the first place, there is no clear
sign by which to distinguish races from species, as is evident from the great
difficulty experienced by naturalists in attempting to discriminate them. As
far as external characters are concerned, many of the races which are
descended from the same stock differ far more than true species of the same
genus; look at the willow-wrens, some of which skilful ornithologists can
hardly distinguish from each other except by their nests; look at the wild
swans, and compare the distinct species of these genera with the races of
domestic ducks, poultry, and pigeons; and so again with plants, compare the
cabbages, almonds, peaches and nectarines, &c. with the species of many
genera. St Hilaire has even remarked that there is a greater difference in size
between races, as in dogs (for he believes all have descended from one
stock), than between the species of any one genus; nor is this surprising,
considering that amount of food and consequently of growth is the element
of change over which man has most power. I may refer to a former
statement, that breeders believe the growth of one part or strong action of
one function causes a decrease in other parts; for this seems in some degree
analogous to the law of “organic compensation{260},” which many naturalists
believe holds good. To give an instance of this law of compensation,—those
species of Carnivora which have the canine teeth greatly developed have
certain molar teeth deficient; or again, in that division of the Crustaceans in
which the tail is much developed, the thorax is little so, and the converse.
The points of difference between different races is often strikingly
analogous to that between species of the same genus: trifling spots or marks
of colour{261} (as the bars on pigeons’ wings) are often preserved in races of
plants and animals, precisely in the same manner as similar trifling
characters often pervade all the species of a genus, and even of a family.
Flowers in varying their colours often become veined and spotted and the
leaves become divided like true species: it is known that the varieties of the
same plant never have red, blue and yellow flowers, though the hyacinth
makes a very near approach to an exception{262}; and different species of the
same genus seldom, though sometimes they have flowers of these three
colours. Dun-coloured horses having a dark stripe down their backs, and

certain domestic asses having transverse bars on their legs, afford striking
examples of a variation analogous in character to the distinctive marks of
other species of the same genus.

External characters of Hybrids and Mongrels.
There is, however, as it appears to me, a more important method of
comparison between species and races, namely the character of the
offspring{263} when species are crossed and when races are crossed: I
believe, in no one respect, except in sterility, is there any difference. It
would, I think, be a marvellous fact, if species have been formed by distinct
acts of creation, that they should act upon each other in uniting, like races
descended from a common stock. In the first place, by repeated crossing
one species can absorb and wholly obliterate the characters of another, or of
several other species, in the same manner as one race will absorb by
crossing another race. Marvellous, that one act of creation should absorb
another or even several acts of creation! The offspring of species, that is
hybrids, and the offspring of races, that is mongrels, resemble each other in
being either intermediate in character (as is most frequent in hybrids) or in
resembling sometimes closely one and sometimes the other parent; in both
the offspring produced by the same act of conception sometimes differ in
their degree of resemblance; both hybrids and mongrels sometimes retain a
certain part or organ very like that of either parent, both, as we have seen,
become in succeeding generations variable; and this tendency to vary can
be transmitted by both; in both for many generations there is a strong
tendency to reversion to their ancestral form. In the case of a hybrid
laburnum and of a supposed mongrel vine different parts of the same plants
took after each of their two parents. In the hybrids from some species, and
in the mongrel of some races, the offspring differ according as which of the
two species, or of the two races, is the father (as in the common mule and
hinny) and which the mother. Some races will breed together, which differ
so greatly in size, that the dam often perishes in labour; so it is with some
species when crossed; when the dam of one species has borne offspring to
the male of another species, her succeeding offspring are sometimes stained
(as in Lord Morton’s mare by the quagga, wonderful as the fact{264} is) by
this first cross; so agriculturists positively affirm is the case when a pig or
sheep of one breed has produced offspring by the sire of another breed.

Summary of second chapter{265}.
Let us sum up this second chapter. If slight variations do occur in
organic beings in a state of nature; if changes of condition from geological
causes do produce in the course of ages effects analogous to those of
domestication on any, however few, organisms; and how can we doubt it,—
from what is actually known, and from what may be presumed, since
thousands of organisms taken by man for sundry uses, and placed in new
conditions, have varied. If such variations tend to be hereditary; and how
can we doubt it,—when we see shades of expression, peculiar manners,
monstrosities of the strangest kinds, diseases, and a multitude of other
peculiarities, which characterise and form, being inherited, the endless races
(there are 1200 kinds of cabbages{266}) of our domestic plants and animals.
If we admit that every organism maintains its place by an almost
periodically recurrent struggle; and how can we doubt it,—when we know
that all beings tend to increase in a geometrical ratio (as is instantly seen
when the conditions become for a time more favourable); whereas on an
average the amount of food must remain constant, if so, there will be a
natural means of selection, tending to preserve those individuals with any
slight deviations of structure more favourable to the then existing
conditions, and tending to destroy any with deviations of an opposite
nature. If the above propositions be correct, and there be no law of nature
limiting the possible amount of variation, new races of beings will,—
perhaps only rarely, and only in some few districts,—be formed.

Limits of Variation.
That a limit to variation does exist in nature is assumed by most authors,
though I am unable to discover a single fact on which this belief is
grounded{267}. One of the commonest statements is that plants do not
become acclimatised; and I have even observed that kinds not raised by
seed, but propagated by cuttings, &c., are instanced. A good instance has,
however, been advanced in the case of kidney beans, which it is believed
are now as tender as when first introduced. Even if we overlook the
frequent introduction of seed from warmer countries, let me observe that as
long as the seeds are gathered promiscuously from the bed, without
continual observation and careful selection of those plants which have stood
the climate best during their whole growth, the experiment of

acclimatisation has hardly been begun. Are not all those plants and animals,
of which we have the greatest number of races, the oldest domesticated?
Considering the quite recent progress{268} of systematic agriculture and
horticulture, is it not opposed to every fact, that we have exhausted the
capacity of variation in our cattle and in our corn,—even if we have done so
in some trivial points, as their fatness or kind of wool? Will any one say,
that if horticulture continues to flourish during the next few centuries, that
we shall not have numerous new kinds of the potato and Dahlia? But take
two varieties of each of these plants, and adapt them to certain fixed
conditions and prevent any cross for 5000 years, and then again vary their
conditions; try many climates and situations; and who{269} will predict the
number and degrees of difference which might arise from these stocks? I
repeat that we know nothing of any limit to the possible amount of
variation, and therefore to the number and differences of the races, which
might be produced by the natural means of selection, so infinitely more
efficient than the agency of man. Races thus produced would probably be
very “true”; and if from having been adapted to different conditions of
existence, they possessed different constitutions, if suddenly removed to
some new station, they would perhaps be sterile and their offspring would
perhaps be infertile. Such races would be undistinguishable from species.
But is there any evidence that the species, which surround us on all sides,
have been thus produced? This is a question which an examination of the
economy of nature we might expect would answer either in the affirmative
or negative{270}.

CHAPTER III
on the variation of instincts and other mental
attributes under domestication and in state of
nature; on the difficulties in this subject; and on
analogous difficulties with respect to corporeal
structures

Variation of mental attributes under domestication.
I have as yet only alluded to the mental qualities which differ greatly in
different species. Let me here premise that, as will be seen in the Second
Part, there is no evidence and consequently no attempt to show that all
existing organisms have descended from any one common parent-stock, but
that only those have so descended which, in the language of naturalists, are
clearly related to each other. Hence the facts and reasoning advanced in this
chapter do not apply to the first origin of the senses{271}, or of the chief
mental attributes, such as of memory, attention, reasoning, &c., &c., by
which most or all of the great related groups are characterised, any more
than they apply to the first origin of life, or growth, or the power of
reproduction. The application of such facts as I have collected is merely to
the differences of the primary mental qualities and of the instincts in the
species{272} of the several great groups. In domestic animals every observer
has remarked in how great a degree, in the individuals of the same species,
the dispositions, namely courage, pertinacity, suspicion, restlessness,
confidence, temper, pugnaciousness, affection, care of their young, sagacity,
&c., &c., vary. It would require a most able metaphysician to explain how
many primary qualities of the mind must be changed to cause these
diversities of complex dispositions. From these dispositions being inherited,
of which the testimony is unanimous, families and breeds arise, varying in
these respects. I may instance the good and ill temper of different stocks of
bees and of horses,—the pugnacity and courage of game fowls,—the
pertinacity of certain dogs, as bull-dogs, and the sagacity of others,—for

restlessness and suspicion compare a wild rabbit reared with the greatest
care from its earliest age with the extreme tameness of the domestic breed
of the same animal. The offspring of the domestic dogs which have run wild
in Cuba{273}, though caught quite young, are most difficult to tame, probably
nearly as much so as the original parent-stock from which the domestic dog
descended. The habitual “periods” of different families of the same species
differ, for instance, in the time of year of reproduction, and the period of life
when the capacity is acquired, and the hour of roosting (in Malay fowls),
&c., &c. These periodical habits are perhaps essentially corporeal, and may
be compared to nearly similar habits in plants, which are known to vary
extremely. Consensual movements (as called by Müller) vary and are
inherited,—such as the cantering and ambling paces in horses, the tumbling
of pigeons, and perhaps the handwriting, which is sometimes so similar
between father and sons, may be ranked in this class. Manners, and even
tricks which perhaps are only peculiar manners, according to W. Hunter and
my father, are distinctly inherited in cases where children have lost their
parent in early infancy. The inheritance of expression, which often reveals
the finest shades of character, is familiar to everyone.
Again the tastes and pleasures of different breeds vary, thus the
shepherd-dog delights in chasing the sheep, but has no wish to kill them,—
the terrier (see Knight) delights in killing vermin, and the spaniel in finding
game. But it is impossible to separate their mental peculiarities in the way I
have done: the tumbling of pigeons, which I have instanced as a consensual
movement, might be called a trick and is associated with a taste for flying in
a close flock at a great height. Certain breeds of fowls have a taste for
roosting in trees. The different actions of pointers and setters might have
been adduced in the same class, as might the peculiar manner of hunting of
the spaniel. Even in the same breed of dogs, namely in fox-hounds, it is the
fixed opinion of those best able to judge that the different pups are born
with different tendencies; some are best to find their fox in the cover; some
are apt to run straggling, some are best to make casts and to recover the lost
scent, &c.; and that these peculiarities undoubtedly are transmitted to their
progeny. Or again the tendency to point might be adduced as a distinct habit
which has become inherited,—as might the tendency of a true sheep dog (as
I have been assured is the case) to run round the flock instead of directly at
them, as is the case with other young dogs when attempted to be taught. The

"transandantes" sheep{274} in Spain, which for some centuries have been
yearly taken a journey of several hundred miles from one province to
another, know when the time comes, and show the greatest restlessness (like
migratory birds in confinement), and are prevented with difficulty from
starting by themselves, which they sometimes do, and find their own way.
There is a case on good evidence{275} of a sheep which, when she lambed,
would return across a mountainous country to her own birth-place, although
at other times of year not of a rambling disposition. Her lambs inherited this
same disposition, and would go to produce their young on the farm whence
their parent came; and so troublesome was this habit that the whole family
was destroyed.
These facts must lead to the conviction, justly wonderful as it is, that
almost infinitely numerous shades of disposition, of tastes, of peculiar
movements, and even of individual actions, can be modified or acquired by
one individual and transmitted to its offspring. One is forced to admit that
mental phenomena (no doubt through their intimate connection with the
brain) can be inherited, like infinitely numerous and fine differences of
corporeal structure. In the same manner as peculiarities of corporeal
structure slowly acquired or lost during mature life (especially cognisant
«?» in disease), as well as congenital peculiarities, are transmitted; so it
appears to be with the mind. The inherited paces in the horse have no doubt
been acquired by compulsion during the lives of the parents: and temper
and tameness may be modified in a breed by the treatment which the
individuals receive. Knowing that a pig has been taught to point, one would
suppose that this quality in pointer-dogs was the simple result of habit, but
some facts, with respect to the occasional appearance of a similar quality in
other dogs, would make one suspect that it originally appeared in a less
perfect degree, “by chance,” that is from a congenital tendency{276} in the
parent of the breed of pointers. One cannot believe that the tumbling, and
high flight in a compact body, of one breed of pigeons has been taught; and
in the case of the slight differences in the manner of hunting in young fox-
hounds, they are doubtless congenital. The inheritance of the foregoing and
similar mental phenomena ought perhaps to create less surprise, from the
reflection that in no case do individual acts of reasoning, or movements, or
other phenomena connected with consciousness, appear to be transmitted.
An action, even a very complicated one, when from long practice it is

performed unconsciously without any effort (and indeed in the case of
many peculiarities of manners opposed to the will) is said, according to a
common expression, to be performed “instinctively.” Those cases of
languages, and of songs, learnt in early childhood and quite forgotten, being
perfectly repeated during the unconsciousness of illness, appear to me only
a few degrees less wonderful than if they had been transmitted to a second
generation{277}.

Hereditary habits compared with instincts.
The chief characteristics of true instincts appear to be their invariability
and non-improvement during the mature age of the individual animal: the
absence of knowledge of the end, for which the action is performed, being
associated, however, sometimes with a degree of reason; being subject to
mistakes and being associated with certain states of the body or times of the
year or day. In most of these respects there is a resemblance in the above
detailed cases of the mental qualities acquired or modified during
domestication. No doubt the instincts of wild animals are more uniform
than those habits or qualities modified or recently acquired under
domestication, in the same manner and from the same causes that the
corporeal structure in this state is less uniform than in beings in their natural
conditions. I have seen a young pointer point as fixedly, the first day it was
taken out, as any old dog; Magendie says this was the case with a retriever
which he himself reared: the tumbling of pigeons is not probably improved
by age: we have seen that in the case above given that the young sheep
inherited the migratory tendency to their particular birth-place the first time
they lambed. This last fact offers an instance of a domestic instinct being
associated with a state of body; as do the “transandantes” sheep with a time
of year. Ordinarily the acquired instincts of domestic animals seem to
require a certain degree of education (as generally in pointers and
retrievers) to be perfectly developed: perhaps this holds good amongst wild
animals in rather a greater degree than is generally supposed; for instance,
in the singing of birds, and in the knowledge of proper herbs in Ruminants.
It seems pretty clear that bees transmit knowledge from generation to
generation. Lord Brougham{278} insists strongly on ignorance of the end
proposed being eminently characteristic of true instincts; and this appears to
me to apply to many acquired hereditary habits; for instance, in the case of
the young pointer alluded to before, which pointed so steadfastly the first

day that we were obliged several times to carry him away{279}. This puppy
not only pointed at sheep, at large white stones, and at every little bird, but
likewise “backed” the other pointers: this young dog must have been as
unconscious for what end he was pointing, namely to facilitate his master’s
killing game to eat, as is a butterfly which lays her eggs on a cabbage, that
her caterpillars would eat the leaves. So a horse that ambles instinctively,
manifestly is ignorant that he performs that peculiar pace for the ease of
man; and if man had never existed, he would never have ambled. The
young pointer pointing at white stones appears to be as much a mistake of
its acquired instinct, as in the case of flesh-flies laying their eggs on certain
flowers instead of putrifying meat. However true the ignorance of the end
may generally be, one sees that instincts are associated with some degree of
reason; for instance, in the case of the tailor-bird, who spins threads with
which to make her nest «yet» will use artificial threads when she can
procure them{280}; so it has been known that an old pointer has broken his
point and gone round a hedge to drive out a bird towards his master{281}.
There is one other quite distinct method by which the instincts or habits
acquired under domestication may be compared with those given by nature,
by a test of a fundamental kind; I mean the comparison of the mental
powers of mongrels and hybrids. Now the instincts, or habits, tastes, and
dispositions of one breed of animals, when crossed with another breed, for
instance a shepherd-dog with a harrier, are blended and appear in the same
curiously mixed degree, both in the first and succeeding generations,
exactly as happens when one species is crossed with another{282}. This
would hardly be the case if there was any fundamental difference between
the domestic and natural instinct{283}; if the former were, to use a
metaphorical expression, merely superficial.

Variation in the mental attributes of wild animals.
With respect to the variation{284} of the mental powers of animals in a
wild state, we know that there is a considerable difference in the disposition
of different individuals of the same species, as is recognised by all those
who have had the charge of animals in a menagerie. With respect to the
wildness of animals, that is fear directed particularly against man, which
appears to be as true an instinct as the dread of a young mouse of a cat, we
have excellent evidence that it is slowly acquired and becomes hereditary. It

is also certain that, in a natural state, individuals of the same species lose or
do not practice their migratory instincts—as woodcocks in Madeira. With
respect to any variation in the more complicated instincts, it is obviously
most difficult to detect, even more so than in the case of corporeal structure,
of which it has been admitted the variation is exceedingly small, and
perhaps scarcely any in the majority of species at any one period. Yet, to
take one excellent case of instinct, namely the nests of birds, those who
have paid most attention to the subject maintain that not only certain
individuals «? species» seem to be able to build very imperfectly, but that a
difference in skill may not unfrequently be detected between
individuals{285}. Certain birds, moreover, adapt their nests to circumstances;
the water-ouzel makes no vault when she builds under cover of a rock—the
sparrow builds very differently when its nest is in a tree or in a hole, and the
golden-crested wren sometimes suspends its nest below and sometimes
places it on the branches of trees.

Principles of Selection applicable to instincts.
As the instincts of a species are fully as important to its preservation and
multiplication as its corporeal structure, it is evident that if there be the
slightest congenital differences in the instincts and habits, or if certain
individuals during their lives are induced or compelled to vary their habits,
and if such differences are in the smallest degree more favourable, under
slightly modified external conditions, to their preservation, such individuals
must in the long run have a better chance of being preserved and of
multiplying{286}. If this be admitted, a series of small changes may, as in the
case of corporeal structure, work great changes in the mental powers, habits
and instincts of any species.

Difficulties in the acquirement of complex instincts by Selection.
Every one will at first be inclined to explain (as I did for a long time)
that many of the more complicated and wonderful instincts could not be
acquired in the manner here supposed{287}. The Second Part of this work is
devoted to the general consideration of how far the general economy of
nature justifies or opposes the belief that related species and genera are
descended from common stocks; but we may here consider whether the
instincts of animals offer such a primâ facie case of impossibility of gradual

acquirement, as to justify the rejection of any such theory, however strongly
it may be supported by other facts. I beg to repeat that I wish here to
consider not the probability but the possibility of complicated instincts
having been acquired by the slow and long-continued selection of very
slight (either congenital or produced by habit) modifications of foregoing
simpler instincts; each modification being as useful and necessary, to the
species practising it, as the most complicated kind.
First, to take the case of birds’-nests; of existing species (almost
infinitely few in comparison with the multitude which must have existed,
since the period of the new Red Sandstone of N. America, of whose habits
we must always remain ignorant) a tolerably perfect series could be made
from eggs laid on the bare ground, to others with a few sticks just laid
round them, to a simple nest like the wood-pigeons, to others more and
more complicated: now if, as is asserted, there occasionally exist slight
differences in the building powers of an individual, and if, which is at least
probable, that such differences would tend to be inherited, then we can see
that it is at least possible that the nidificatory instincts may have been
acquired by the gradual selection, during thousands and thousands of
generations, of the eggs and young of those individuals, whose nests were
in some degree better adapted to the preservation of their young, under the
then existing conditions. One of the most surprising instincts on record is
that of the Australian bush-turkey, whose eggs are hatched by the heat
generated from a huge pile of fermenting materials, which it heaps together;
but here the habits of an allied species show how this instinct might possibly
have been acquired. This second species inhabits a tropical district, where
the heat of the sun is sufficient to hatch its eggs; this bird, burying its eggs,
apparently for concealment, under a lesser heap of rubbish, but of a dry
nature, so as not to ferment. Now suppose this bird to range slowly into a
climate which was cooler, and where leaves were more abundant, in that
case, those individuals, which chanced to have their collecting instinct
strongest developed, would make a somewhat larger pile, and the eggs,
aided during some colder season, under the slightly cooler climate by the
heat of incipient fermentation, would in the long run be more freely hatched
and would probably produce young ones with the same more highly
developed collecting tendencies; of these again, those with the best
developed powers would again tend to rear most young. Thus this strange

instinct might possibly be acquired, every individual bird being as ignorant
of the laws of fermentation, and the consequent development of heat, as we
know they must be.
Secondly, to take the case of animals feigning death (as it is commonly
expressed) to escape danger. In the case of insects, a perfect series can be
shown, from some insects, which momentarily stand still, to others which
for a second slightly contract their legs, to others which will remain
immovably drawn together for a quarter of an hour, and may be torn
asunder or roasted at a slow fire, without evincing the smallest sign of
sensation. No one will doubt that the length of time, during which each
remains immovable, is well adapted to «favour the insect’s» escape «from»
the dangers to which it is most exposed, and few will deny the possibility of
the change from one degree to another, by the means and at the rate already
explained. Thinking it, however, wonderful (though not impossible) that the
attitude of death should have been acquired by methods which imply no
imitation, I compared several species, when feigning, as is said, death, with
others of the same species really dead, and their attitudes were in no one
case the same.
Thirdly, in considering many instincts it is useful to endeavour to
separate the faculty{288} by which they perform it, and the mental power
which urges to the performance, which is more properly called an instinct.
We have an instinct to eat, we have jaws &c. to give us the faculty to do so.
These faculties are often unknown to us: bats, with their eyes destroyed, can
avoid strings suspended across a room, we know not at present by what
faculty they do this. Thus also, with migratory birds, it is a wonderful
instinct which urges them at certain times of the year to direct their course
in certain directions, but it is a faculty by which they know the time and
find their way. With respect to time{289}, man without seeing the sun can
judge to a certain extent of the hour, as must those cattle which come down
from the inland mountains to feed on sea-weed left bare at the changing
hour of low-water{290}. A hawk (D’Orbigny) seems certainly to have
acquired a knowledge of a period of every 21 days. In the cases already
given of the sheep which travelled to their birth-place to cast their lambs,
and the sheep in Spain which know their time of march{291}, we may
conjecture that the tendency to move is associated, we may then call it
instinctively, with some corporeal sensations. With respect to direction we

can easily conceive how a tendency to travel in a certain course may
possibly have been acquired, although we must remain ignorant how birds
are able to preserve any direction whatever in a dark night over the wide
ocean. I may observe that the power of some savage races of mankind to
find their way, although perhaps wholly different from the faculty of birds,
is nearly as unintelligible to us. Bellinghausen, a skilful navigator, describes
with the utmost wonder the manner in which some Esquimaux guided him
to a certain point, by a course never straight, through newly formed
hummocks of ice, on a thick foggy day, when he with a compass found it
impossible, from having no landmarks, and from their course being so
extremely crooked, to preserve any sort of uniform direction: so it is with
Australian savages in thick forests. In North and South America many birds
slowly travel northward and southward, urged on by the food they find, as
the seasons change; let them continue to do this, till, as in the case of the
sheep in Spain, it has become an urgent instinctive desire, and they will
gradually accelerate their journey. They would cross narrow rivers, and if
these were converted by subsidence into narrow estuaries, and gradually
during centuries to arms of the sea, still we may suppose their restless
desire of travelling onwards would impel them to cross such an arm, even if
it had become of great width beyond their span of vision. How they are able
to preserve a course in any direction, I have said, is a faculty unknown to
us. To give another illustration of the means by which I conceive it possible
that the direction of migrations have been determined. Elk and reindeer in
N. America annually cross, as if they could marvellously smell or see at the
distance of a hundred miles, a wide tract of absolute desert, to arrive at
certain islands where there is a scanty supply of food; the changes of
temperature, which geology proclaims, render it probable that this desert
tract formerly supported some vegetation, and thus these quadrupeds might
have been annually led on, till they reached the more fertile spots, and so
acquired, like the sheep of Spain, their migratory powers.
Fourthly, with respect to the combs of the hive-bee{292}; here again we
must look to some faculty or means by which they make their hexagonal
cells, without indeed we view these instincts as mere machines. At present
such a faculty is quite unknown: Mr Waterhouse supposes that several bees
are led by their instinct to excavate a mass of wax to a certain thinness, and
that the result of this is that hexagons necessarily remain. Whether this or

some other theory be true, some such means they must possess. They
abound, however, with true instincts, which are the most wonderful that are
known. If we examine the little that is known concerning the habits of other
species of bees, we find much simpler instincts: the humble bee merely fills
rude balls of wax with honey and aggregates them together with little order
in a rough nest of grass. If we knew the instinct of all the bees, which ever
had existed, it is not improbable that we should have instincts of every
degree of complexity, from actions as simple as a bird making a nest, and
rearing her young, to the wonderful architecture and government of the
hive-bee; at least such is possible, which is all that I am here considering.
Finally, I will briefly consider under the same point of view one other
class of instincts, which have often been advanced as truly wonderful,
namely parents bringing food to their young which they themselves neither
like nor partake of{293};—for instance, the common sparrow, a granivorous
bird, feeding its young with caterpillars. We might of course look into the
case still earlier, and seek how an instinct in the parent, of feeding its young
at all, was first derived; but it is useless to waste time in conjectures on a
series of gradations from the young feeding themselves and being slightly
and occasionally assisted in their search, to their entire food being brought
to them. With respect to the parent bringing a different kind of food from its
own kind, we may suppose either that the remote stock, whence the sparrow
and other congenerous birds have descended, was insectivorous, and that its
own habits and structure have been changed, whilst its ancient instincts
with respect to its young have remained unchanged; or we may suppose that
the parents have been induced to vary slightly the food of their young, by a
slight scarcity of the proper kind (or by the instincts of some individuals not
being so truly developed), and in this case those young which were most
capable of surviving were necessarily most often preserved, and would
themselves in time become parents, and would be similarly compelled to
alter their food for their young. In the case of those animals, the young of
which feed themselves, changes in their instincts for food, and in their
structure, might be selected from slight variations, just as in mature
animals. Again, where the food of the young depends on where the mother
places her eggs, as in the case of the caterpillars of the cabbage-butterfly,
we may suppose that the parent stock of the species deposited her eggs
sometimes on one kind and sometimes on another of congenerous plants (as

some species now do), and if the cabbage suited the caterpillars better than
any other plant, the caterpillars of those butterflies, which had chosen the
cabbage, would be most plentifully reared, and would produce butterflies
more apt to lay their eggs on the cabbage than on the other congenerous
plants.
However vague and unphilosophical these conjectures may appear, they
serve, I think, to show that one’s first impulse utterly to reject any theory
whatever, implying a gradual acquirement of these instincts, which for ages
have excited man’s admiration, may at least be delayed. Once grant that
dispositions, tastes, actions or habits can be slightly modified, either by
slight congenital differences (we must suppose in the brain) or by the force
of external circumstances, and that such slight modifications can be
rendered inheritable,—a proposition which no one can reject,—and it will
be difficult to put any limit to the complexity and wonder of the tastes and
habits which may possibly be thus acquired.

Difficulties in the acquirement by Selection of complex corporeal
structures.
After the past discussion it will perhaps be convenient here to consider
whether any particular corporeal organs, or the entire structure of any
animals, are so wonderful as to justify the rejection primâ facie of our
theory{294}. In the case of the eye, as with the more complicated instincts, no
doubt one’s first impulse is to utterly reject every such theory. But if the eye
from its most complicated form can be shown to graduate into an
exceedingly simple state,—if selection can produce the smallest change,
and if such a series exists, then it is clear (for in this work we have nothing
to do with the first origin of organs in their simplest forms{295}) that it may
possibly have been acquired by gradual selection of slight, but in each case,
useful deviations{296}. Every naturalist, when he meets with any new and
singular organ, always expects to find, and looks for, other and simpler
modifications of it in other beings. In the case of the eye, we have a
multitude of different forms, more or less simple, not graduating into each
other, but separated by sudden gaps or intervals; but we must recollect how
incomparably greater would the multitude of visual structures be if we had
the eyes of every fossil which ever existed. We shall discuss the probable
vast proportion of the extinct to the recent in the succeeding Part.

Notwithstanding the large series of existing forms, it is most difficult even
to conjecture by what intermediate stages very many simple organs could
possibly have graduated into complex ones: but it should be here borne in
mind, that a part having originally a wholly different function, may on the
theory of gradual selection be slowly worked into quite another use; the
gradations of forms, from which naturalists believe in the hypothetical
metamorphosis of part of the ear into the swimming bladder in fishes{297},
and in insects of legs into jaws, show the manner in which this is possible.
As under domestication, modifications of structure take place, without any
continued selection, which man finds very useful, or valuable for curiosity
(as the hooked calyx of the teazle, or the ruff round some pigeons’ necks),
so in a state of nature some small modifications, apparently beautifully
adapted to certain ends, may perhaps be produced from the accidents of the
reproductive system, and be at once propagated without long-continued
selection of small deviations towards that structure{298}. In conjecturing by
what stages any complicated organ in a species may have arrived at its
present state, although we may look to the analogous organs in other
existing species, we should do this merely to aid and guide our
imaginations; for to know the real stages we must look only through one
line of species, to one ancient stock, from which the species in question has
descended. In considering the eye of a quadruped, for instance, though we
may look at the eye of a molluscous animal or of an insect, as a proof how
simple an organ will serve some of the ends of vision; and at the eye of a
fish as a nearer guide of the manner of simplification; we must remember
that it is a mere chance (assuming for a moment the truth of our theory) if
any existing organic being has preserved any one organ, in exactly the same
condition, as it existed in the ancient species at remote geological periods.
The nature or condition of certain structures has been thought by some
naturalists to be of no use to the possessor{299}, but to have been formed
wholly for the good of other species; thus certain fruit and seeds have been
thought to have been made nutritious for certain animals—numbers of
insects, especially in their larval state, to exist for the same end—certain
fish to be bright coloured to aid certain birds of prey in catching them, &c.
Now could this be proved (which I am far from admitting) the theory of
natural selection would be quite overthrown; for it is evident that selection
depending on the advantage over others of one individual with some slight

deviation would never produce a structure or quality profitable only to
another species. No doubt one being takes advantage of qualities in another,
and may even cause its extermination; but this is far from proving that this
quality was produced for such an end. It may be advantageous to a plant to
have its seeds attractive to animals, if one out of a hundred or a thousand
escapes being digested, and thus aids dissemination: the bright colours of a
fish may be of some advantage to it, or more probably may result from
exposure to certain conditions in favourable haunts for food,
notwithstanding it becomes subject to be caught more easily by certain
birds.
If instead of looking, as above, at certain individual organs, in order to
speculate on the stages by which their parts have been matured and
selected, we consider an individual animal, we meet with the same or
greater difficulty, but which, I believe, as in the case of single organs, rests
entirely on our ignorance. It may be asked by what intermediate forms
could, for instance, a bat possibly have passed; but the same question might
have been asked with respect to the seal, if we had not been familiar with
the otter and other semi-aquatic carnivorous quadrupeds. But in the case of
the bat, who can say what might have been the habits of some parent form
with less developed wings, when we now have insectivorous opossums and
herbivorous squirrels fitted for merely gliding through the air{300}. One
species of bat is at present partly aquatic in its habits{301}. Woodpeckers and
tree-frogs are especially adapted, as their names express, for climbing trees;
yet we have species of both inhabiting the open plains of La Plata, where a
tree does not exist{302}. I might argue from this circumstance that a structure
eminently fitted for climbing trees might descend from forms inhabiting a
country where a tree did not exist. Notwithstanding these and a multitude of
other well-known facts, it has been maintained by several authors that one
species, for instance of the carnivorous order, could not pass into another,
for instance into an otter, because in its transitional state its habits would
not be adapted to any proper conditions of life; but the jaguar{303} is a
thoroughly terrestrial quadruped in its structure, yet it takes freely to the
water and catches many fish; will it be said that it is impossible that the
conditions of its country might become such that the jaguar should be
driven to feed more on fish than they now do; and in that case is it
impossible, is it not probable, that any the slightest deviation in its instincts,

its form of body, in the width of its feet, and in the extension of the skin
(which already unites the base of its toes) would give such individuals a
better chance of surviving and propagating young with similar, barely
perceptible (though thoroughly exercised), deviations{304}? Who will say
what could thus be effected in the course of ten thousand generations? Who
can answer the same question with respect to instincts? If no one can, the
possibility (for we are not in this chapter considering the probability) of
simple organs or organic beings being modified by natural selection and the
effects of external agencies into complicated ones ought not to be
absolutely rejected.

PART II{305}
on the evidence favourable and opposed to the
view that species are naturally formed races,
descended from common stocks

CHAPTER IV
on the number of intermediate forms required on
the theory of common descent; and on their
absence in a fossil state

I must here premise that, according to the view ordinarily received, the
myriads of organisms, which have during past and present times peopled
this world, have been created by so many distinct acts of creation. It is
impossible to reason concerning the will of the Creator, and therefore,
according to this view, we can see no cause why or why not the individual
organism should have been created on any fixed scheme. That all the
organisms of this world have been produced on a scheme is certain from
their general affinities; and if this scheme can be shown to be the same with
that which would result from allied organic beings descending from
common stocks, it becomes highly improbable that they have been
separately created by individual acts of the will of a Creator. For as well
might it be said that, although the planets move in courses conformably to
the law of gravity, yet we ought to attribute the course of each planet to the
individual act of the will of the Creator{306}. It is in every case more
conformable with what we know of the government of this earth, that the
Creator should have imposed only general laws. As long as no method was
known by which races could become exquisitely adapted to various ends,
whilst the existence of species was thought to be proved by the sterility{307}
of their offspring, it was allowable to attribute each organism to an
individual act of creation. But in the two former chapters it has (I think)
been shown that the production, under existing conditions, of exquisitely
adapted species, is at least possible. Is there then any direct evidence in
favour «of» or against this view? I believe that the geographical distribution
of organic beings in past and present times, the kind of affinity linking them
together, their so-called “metamorphic” and “abortive” organs, appear in
favour of this view. On the other hand, the imperfect evidence of the

continuousness of the organic series, which, we shall immediately see, is
required on our theory, is against it; and is the most weighty objection{308}.
The evidence, however, even on this point, as far as it goes, is favourable;
and considering the imperfection of our knowledge, especially with respect
to past ages, it would be surprising if evidence drawn from such sources
were not also imperfect.
As I suppose that species have been formed in an analogous manner
with the varieties of the domesticated animals and plants, so must there
have existed intermediate forms between all the species of the same group,
not differing more than recognised varieties differ. It must not be supposed
necessary that there should have existed forms exactly intermediate in
character between any two species of a genus, or even between any two
varieties of a species; but it is necessary that there should have existed
every intermediate form between the one species or variety of the common
parent, and likewise between the second species or variety, and this same
common parent. Thus it does not necessarily follow that there ever has
existed «a» series of intermediate sub-varieties (differing no more than the
occasional seedlings from the same seed-capsule,) between broccoli and
common red cabbage; but it is certain that there has existed, between
broccoli and the wild parent cabbage, a series of such intermediate
seedlings, and again between red cabbage and the wild parent cabbage: so
that the broccoli and red cabbage are linked together, but not necessarily by
directly intermediate forms{309}. It is of course possible that there may have
been directly intermediate forms, for the broccoli may have long since
descended from a common red cabbage, and this from the wild cabbage. So
on my theory, it must have been with species of the same genus. Still more
must the supposition be avoided that there has necessarily ever existed
(though one may have descended from «the» other) directly intermediate
forms between any two genera or families—for instance between the genus
Sus and the Tapir{310}; although it is necessary that intermediate forms (not
differing more than the varieties of our domestic animals) should have
existed between Sus and some unknown parent form, and Tapir with this
same parent form. The latter may have differed more from Sus and Tapir
than these two genera now differ from each other. In this sense, according
to our theory, there has been a gradual passage (the steps not being wider
apart than our domestic varieties) between the species of the same genus,

between genera of the same family, and between families of the same order,
and so on, as far as facts, hereafter to be given, lead us; and the number of
forms which must have at former periods existed, thus to make good this
passage between different species, genera, and families, must have been
almost infinitely great.
What evidence{311} is there of a number of intermediate forms having
existed, making a passage in the above sense, between the species of the
same groups? Some naturalists have supposed that if every fossil which
now lies entombed, together with all existing species, were collected
together, a perfect series in every great class would be formed. Considering
the enormous number of species requisite to effect this, especially in the
above sense of the forms not being directly intermediate between the
existing species and genera, but only intermediate by being linked through a
common but often widely different ancestor, I think this supposition highly
improbable. I am however far from underrating the probable number of
fossilised species: no one who has attended to the wonderful progress of
palæontology during the last few years will doubt that we as yet have found
only an exceedingly small fraction of the species buried in the crust of the
earth. Although the almost infinitely numerous intermediate forms in no one
class may have been preserved, it does not follow that they have not
existed. The fossils which have been discovered, it is important to remark,
do tend, the little way they go, to make good the series; for as observed by
Buckland they all fall into or between existing groups{312}. Moreover, those
that fall between our existing groups, fall in, according to the manner
required by our theory, for they do not directly connect two existing species
of different groups, but they connect the groups themselves: thus the
Pachydermata and Ruminantia are now separated by several characters,
«for instance» the Pachydermata{313} have both a tibia and fibula, whilst
Ruminantia have only a tibia; now the fossil Macrauchenia has a leg bone
exactly intermediate in this respect, and likewise has some other
intermediate characters. But the Macrauchenia does not connect any one
species of Pachydermata with some one other of Ruminantia but it shows
that these two groups have at one time been less widely divided. So have
fish and reptiles been at one time more closely connected in some points
than they now are. Generally in those groups in which there has been most
change, the more ancient the fossil, if not identical with recent, the more

often it falls between existing groups, or into small existing groups which
now lie between other large existing groups. Cases like the foregoing, of
which there are many, form steps, though few and far between, in a series of
the kind required by my theory.
As I have admitted the high improbability, that if every fossil were
disinterred, they would compose in each of the Divisions of Nature a
perfect series of the kind required; consequently I freely admit, that if those
geologists are in the right who consider the lowest known formation as
contemporaneous with the first appearances of life{314}; or the several
formations as at all closely consecutive; or any one formation as containing
a nearly perfect record of the organisms which existed during the whole
period of its deposition in that quarter of the globe;—if such propositions
are to be accepted, my theory must be abandoned.
If the Palæozoic system is really contemporaneous with the first
appearance of life, my theory must be abandoned, both inasmuch as it limits
from shortness of time the total number of forms which can have existed on
this world, and because the organisms, as fish, mollusca{315} and star-fish
found in its lower beds, cannot be considered as the parent forms of all the
successive species in these classes. But no one has yet overturned the
arguments of Hutton and Lyell, that the lowest formations known to us are
only those which have escaped being metamorphosed «illegible»; if we
argued from some considerable districts, we might have supposed that even
the Cretaceous system was that in which life first appeared. From the
number of distant points, however, in which the Silurian system has been
found to be the lowest, and not always metamorphosed, there are some
objections to Hutton’s and Lyell’s view; but we must not forget that the now
existing land forms only 1/5 part of the superficies of the globe, and that
this fraction is only imperfectly known. With respect to the fewness of the
organisms found in the Silurian and other Palæozoic formations, there is
less difficulty, inasmuch as (besides their gradual obliteration) we can
expect formations of this vast antiquity to escape entire denudation, only
when they have been accumulated over a wide area, and have been
subsequently protected by vast superimposed deposits: now this could
generally only hold good with deposits accumulating in a wide and deep
ocean, and therefore unfavourable to the presence of many living things. A
mere narrow and not very thick strip of matter, deposited along a coast

where organisms most abound, would have no chance of escaping
denudation and being preserved to the present time from such immensely
distant ages{316}.
If the several known formations are at all nearly consecutive in time,
and preserve a fair record of the organisms which have existed, my theory
must be abandoned. But when we consider the great changes in
mineralogical nature and texture between successive formations, what vast
and entire changes in the geography of the surrounding countries must
generally have been effected, thus wholly to have changed the nature of the
deposits on the same area. What time such changes must have required!
Moreover how often has it not been found, that between two conformable
and apparently immediately successive deposits a vast pile of water-worn
matter is interpolated in an adjoining district. We have no means of
conjecturing in many cases how long a period{317} has elapsed between
successive formations, for the species are often wholly different: as
remarked by Lyell, in some cases probably as long a period has elapsed
between two formations as the whole Tertiary system, itself broken by wide
gaps.
Consult the writings of any one who has particularly attended to any
one stage in the Tertiary system (and indeed of every system) and see how
deeply impressed he is with the time required for its accumulation{318}.
Reflect on the years elapsed in many cases, since the latest beds containing
only living species have been formed;—see what Jordan Smith says of the
20,000 years since the last bed, which is above the boulder formation in
Scotland, has been upraised; or of the far longer period since the recent
beds of Sweden have been upraised 400 feet, what an enormous period the
boulder formation must have required, and yet how insignificant are the
records (although there has been plenty of elevation to bring up submarine
deposits) of the shells, which we know existed at that time. Think, then,
over the entire length of the Tertiary epoch, and think over the probable
length of the intervals, separating the Secondary deposits. Of these deposits,
moreover, those consisting of sand and pebbles have seldom been
favourable, either to the embedment or to the preservation of fossils{319}.
Nor can it be admitted as probable that any one Secondary formation
contains a fair record even of those organisms which are most easily

preserved, namely hard marine bodies. In how many cases have we not
certain evidence that between the deposition of apparently closely
consecutive beds, the lower one existed for an unknown time as land,
covered with trees. Some of the Secondary formations which contain most
marine remains appear to have been formed in a wide and not deep sea, and
therefore only those marine animals which live in such situations would be
preserved{320}. In all cases, on indented rocky coasts, or any other coast,
where sediment is not accumulating, although often highly favourable to
marine animals, none can be embedded: where pure sand and pebbles are
accumulating few or none will be preserved. I may here instance the great
western line of the S. American coast{321}, tenanted by many peculiar
animals, of which none probably will be preserved to a distant epoch. From
these causes, and especially from such deposits as are formed along a line
of coast, steep above and below water, being necessarily of little width, and
therefore more likely to be subsequently denuded and worn away, we can
see why it is improbable that our Secondary deposits contain a fair record of
the Marine Fauna of any one period. The East Indian Archipelago offers an
area, as large as most of our Secondary deposits, in which there are wide
and shallow seas, teeming with marine animals, and in which sediment is
accumulating; now supposing that all the hard marine animals, or rather
those having hard parts to preserve, were preserved to a future age,
excepting those which lived on rocky shores where no sediment or only
sand and gravel were accumulating, and excepting those embedded along
the steeper coasts, where only a narrow fringe of sediment was
accumulating, supposing all this, how poor a notion would a person at a
future age have of the Marine Fauna of the present day. Lyell{322} has
compared the geological series to a work of which only the few latter but
not consecutive chapters have been preserved; and out of which, it may be
added, very many leaves have been torn, the remaining ones only
illustrating a scanty portion of the Fauna of each period. On this view, the
records of anteceding ages confirm my theory; on any other they destroy it.
Finally, if we narrow the question into, why do we not find in some
instances every intermediate form between any two species? the answer
may well be that the average duration of each specific form (as we have
good reason to believe) is immense in years, and that the transition could,
according to my theory, be effected only by numberless small gradations;

and therefore that we should require for this end a most perfect record,
which the foregoing reasoning teaches us not to expect. It might be thought
that in a vertical section of great thickness in the same formation some of
the species ought to be found to vary in the upper and lower parts{323}, but it
may be doubted whether any formation has gone on accumulating without
any break for a period as long as the duration of a species; and if it had done
so, we should require a series of specimens from every part. How rare must
be the chance of sediment accumulating for some 20 or 30 thousand years
on the same spot{324}, with the bottom subsiding, so that a proper depth
might be preserved for any one species to continue living: what an amount
of subsidence would be thus required, and this subsidence must not destroy
the source whence the sediment continued to be derived. In the case of
terrestrial animals, what chance is there when the present time is become a
pleistocene formation (at an earlier period than this, sufficient elevation to
expose marine beds could not be expected), what chance is there that future
geologists will make out the innumerable transitional sub-varieties, through
which the short-horned and long-horned cattle (so different in shape of
body) have been derived from the same parent stock{325}? Yet this transition
has been effected in the same country, and in a far shorter time, than would
be probable in a wild state, both contingencies highly favourable for the
future hypothetical geologists being enabled to trace the variation.

CHAPTER V
gradual appearance and disappearance of
{326}
species

In the Tertiary system, in the last uplifted beds, we find all the species
recent and living in the immediate vicinity; in rather older beds we find
only recent species, but some not living in the immediate vicinity{327}; we
then find beds with two or three or a few more extinct or very rare species;
then considerably more extinct species, but with gaps in the regular
increase; and finally we have beds with only two or three or not one living
species. Most geologists believe that the gaps in the percentage, that is the
sudden increments, in the number of the extinct species in the stages of the
Tertiary system are due to the imperfection of the geological record. Hence
we are led to believe that the species in the Tertiary system have been
gradually introduced; and from analogy to carry on the same view to the
Secondary formations. In these latter, however, entire groups of species
generally come in abruptly; but this would naturally result, if, as argued in
the foregoing chapter, these Secondary deposits are separated by wide
epochs. Moreover it is important to observe that, with our increase of
knowledge, the gaps between the older formations become fewer and
smaller; geologists of a few years standing remember how beautifully has
the Devonian system{328} come in between the Carboniferous and Silurian
formations. I need hardly observe that the slow and gradual appearance of
new forms follows from our theory, for to form a new species, an old one
must not only be plastic in its organization, becoming so probably from
changes in the conditions of its existence, but a place in the natural
economy of the district must [be made,] come to exist, for the selection of
some new modification of its structure, better fitted to the surrounding
conditions than are the other individuals of the same or other species{329}.
In the Tertiary system the same facts, which make us admit as probable
that new species have slowly appeared, lead to the admission that old ones
have slowly disappeared, not several together, but one after another; and by
analogy one is induced to extend this belief to the Secondary and Palæozoic

epochs. In some cases, as the subsidence of a flat country, or the breaking or
the joining of an isthmus, and the sudden inroad of many new and
destructive species, extinction might be locally sudden. The view
entertained by many geologists, that each fauna of each Secondary epoch
has been suddenly destroyed over the whole world, so that no succession
could be left for the production of new forms, is subversive of my theory,
but I see no grounds whatever to admit such a view. On the contrary, the
law, which has been made out, with reference to distinct epochs, by
independent observers, namely, that the wider the geographical range of a
species the longer is its duration in time, seems entirely opposed to any
universal extermination{330}. The fact of species of mammiferous animals
and fish being renewed at a quicker rate than mollusca, though both aquatic;
and of these the terrestrial genera being renewed quicker than the marine;
and the marine mollusca being again renewed quicker than the Infusorial
animalcula, all seem to show that the extinction and renewal of species does
not depend on general catastrophes, but on the particular relations of the
several classes to the conditions to which they are exposed{331}.
Some authors seem to consider the fact of a few species having
survived{332} amidst a number of extinct forms (as is the case with a tortoise
and a crocodile out of the vast number of extinct sub-Himalayan fossils) as
strongly opposed to the view of species being mutable. No doubt this would
be the case, if it were presupposed with Lamarck that there was some
inherent tendency to change and development in all species, for which
supposition I see no evidence. As we see some species at present adapted to
a wide range of conditions, so we may suppose that such species would
survive unchanged and unexterminated for a long time; time generally
being from geological causes a correlative of changing conditions. How at
present one species becomes adapted to a wide range, and another species
to a restricted range of conditions, is of difficult explanation.

Extinction of species.
The extinction of the larger quadrupeds, of which we imagine we better
know the conditions of existence, has been thought little less wonderful
than the appearance of new species; and has, I think, chiefly led to the
belief of universal catastrophes. When considering the wonderful
disappearance within a late period, whilst recent shells were living, of the

numerous great and small mammifers of S. America, one is strongly
induced to join with the catastrophists. I believe, however, that very
erroneous views are held on this subject. As far as is historically known, the
disappearance of species from any one country has been slow—the species
becoming rarer and rarer, locally extinct, and finally lost{333}. It may be
objected that this has been effected by man’s direct agency, or by his
indirect agency in altering the state of the country; in this latter case,
however, it would be difficult to draw any just distinction between his
agency and natural agencies. But we now know in the later Tertiary
deposits, that shells become rarer and rarer in the successive beds, and
finally disappear: it has happened, also, that shells common in a fossil state,
and thought to have been extinct, have been found to be still living species,
but very rare ones{334}. If the rule is that organisms become extinct by
becoming rarer and rarer, we ought not to view their extinction, even in the
case of the larger quadrupeds, as anything wonderful and out of the
common course of events. For no naturalist thinks it wonderful that one
species of a genus should be rare and another abundant, notwithstanding he
be quite incapable of explaining the causes of the comparative rareness{335}.
Why is one species of willow-wren or hawk or woodpecker common in
England, and another extremely rare: why at the Cape of Good Hope is one
species of rhinoceros or antelope far more abundant than other species?
Why again is the same species much more abundant in one district of a
country than in another district? No doubt there are in each case good
causes: but they are unknown and unperceived by us. May we not then
safely infer that as certain causes are acting unperceived around us, and are
making one species to be common and another exceedingly rare, that they
might equally well cause the final extinction of some species without being
perceived by us? We should always bear in mind that there is a recurrent
struggle for life in every organism, and that in every country a destroying
agency is always counteracting the geometrical tendency to increase in
every species; and yet without our being able to tell with certainty at what
period of life, or at what period of the year, the destruction falls the
heaviest. Ought we then to expect to trace the steps by which this
destroying power, always at work and scarcely perceived by us, becomes
increased, and yet if it continues to increase ever so slowly (without the
fertility of the species in question be likewise increased) the average
number of the individuals of that species must decrease, and become finally

lost. I may give a single instance of a check causing local extermination
which might long have escaped discovery{336}; the horse, though swarming
in a wild state in La Plata, and likewise under apparently the most
unfavourable conditions in the scorched and alternately flooded plains of
Caraccas, will not in a wild state extend beyond a certain degree of latitude
into the intermediate country of Paraguay; this is owing to a certain fly
depositing its eggs on the navels of the foals: as, however, man with a little
care can rear horses in a tame state abundantly in Paraguay, the problem of
its extinction is probably complicated by the greater exposure of the wild
horse to occasional famine from the droughts, to the attacks of the jaguar
and other such evils. In the Falkland Islands the check to the increase of the
wild horse is said to be loss of the sucking foals{337}, from the stallions
compelling the mares to travel across bogs and rocks in search of food: if
the pasture on these islands decreased a little, the horse, perhaps, would
cease to exist in a wild state, not from the absolute want of food, but from
the impatience of the stallions urging the mares to travel whilst the foals
were too young.
From our more intimate acquaintance with domestic animals, we cannot
conceive their extinction without some glaring agency; we forget that they
would undoubtedly in a state of nature (where other animals are ready to fill
up their place) be acted on in some part of their lives by a destroying
agency, keeping their numbers on an average constant. If the common ox
was known only as a wild S. African species, we should feel no surprise at
hearing that it was a very rare species; and this rarity would be a stage
towards its extinction. Even in man, so infinitely better known than any
other inhabitant of this world, how impossible it has been found, without
statistical calculations, to judge of the proportions of births and deaths, of
the duration of life, and of the increase and decrease of population; and still
less of the causes of such changes: and yet, as has so often been repeated,
decrease in numbers or rarity seems to be the high-road to extinction. To
marvel at the extermination of a species appears to me to be the same thing
as to know that illness is the road to death,—to look at illness as an ordinary
event, nevertheless to conclude, when the sick man dies, that his death has
been caused by some unknown and violent agency{338}.
In a future part of this work we shall show that, as a general rule, groups
of allied species{339} gradually appear and disappear, one after the other, on

the face of the earth, like the individuals of the same species: and we shall
then endeavour to show the probable cause of this remarkable fact.

CHAPTER VI
on the geographical distribution of organic
beings in past and present times

For convenience sake I shall divide this chapter into three sections{340}.
In the first place I shall endeavour to state the laws of the distribution of
existing beings, as far as our present object is concerned; in the second, that
of extinct; and in the third section I shall consider how far these laws accord
with the theory of allied species having a common descent.

Section First.
Distribution of the inhabitants in the different continents.
In the following discussion I shall chiefly refer to terrestrial mammifers,
inasmuch as they are better known; their differences in different countries,
strongly marked; and especially as the necessary means of their transport
are more evident, and confusion, from the accidental conveyance by man of
a species from one district to another district, is less likely to arise. It is
known that all mammifers (as well as all other organisms) are united in one
great system; but that the different species, genera, or families of the same
order inhabit different quarters of the globe. If we divide the land{341} into
two divisions, according to the amount of difference, and disregarding the
numbers of the terrestrial mammifers inhabiting them, we shall have first
Australia including New Guinea; and secondly the rest of the world: if we
make a three-fold division, we shall have Australia, S. America, and the rest
of the world; I must observe that North America is in some respects neutral
land, from possessing some S. American forms, but I believe it is more
closely allied (as it certainly is in its birds, plants and shells) with Europe. If
our division had been four-fold, we should have had Australia, S. America,
Madagascar (though inhabited by few mammifers) and the remaining land:
if five-fold, Africa, especially the southern eastern parts, would have to be
separated from the remainder of the world. These differences in the
mammiferous inhabitants of the several main divisions of the globe cannot,
it is well known, be explained by corresponding differences in their

conditions{342}; how similar are parts of tropical America and Africa; and
accordingly we find some analogous resemblances,—thus both have
monkeys, both large feline animals, both large Lepidoptera, and large dung-
feeding beetles; both have palms and epiphytes; and yet the essential
difference between their productions is as great as between those of the arid
plains of the Cape of Good Hope and the grass-covered savannahs of La
Plata{343}. Consider the distribution of the Marsupialia, which are eminently
characteristic of Australia, and in a lesser degree of S. America; when we
reflect that animals of this division, feeding both on animal and vegetable
matter, frequent the dry open or wooded plains and mountains of Australia,
the humid impenetrable forests of New Guinea and Brazil; the dry rocky
mountains of Chile, and the grassy plains of Banda Oriental, we must look
to some other cause, than the nature of the country, for their absence in
Africa and other quarters of the world.
Furthermore it may be observed that all the organisms inhabiting any
country are not perfectly adapted to it{344}; I mean by not being perfectly
adapted, only that some few other organisms can generally be found better
adapted to the country than some of the aborigines. We must admit this
when we consider the enormous number of horses and cattle which have
run wild during the three last centuries in the uninhabited parts of St
Domingo, Cuba, and S. America; for these animals must have supplanted
some aboriginal ones. I might also adduce the same fact in Australia, but
perhaps it will be objected that 30 or 40 years has not been a sufficient
period to test this power of struggling «with» and overcoming the
aborigines. We know the European mouse is driving before it that of New
Zealand, like the Norway rat has driven before it the old English species in
England. Scarcely an island can be named, where casually introduced plants
have not supplanted some of the native species: in La Plata the Cardoon
covers square leagues of country on which some S. American plants must
once have grown: the commonest weed over the whole of India is an
introduced Mexican poppy. The geologist who knows that slow changes are
in progress, replacing land and water, will easily perceive that even if all the
organisms of any country had originally been the best adapted to it, this
could hardly continue so during succeeding ages without either
extermination, or changes, first in the relative proportional numbers of the
inhabitants of the country, and finally in their constitutions and structure.

Inspection of a map of the world at once shows that the five divisions,
separated according to the greatest amount of difference in the mammifers
inhabiting them, are likewise those most widely separated from each other
by barriers{345} which mammifers cannot pass: thus Australia is separated
from New Guinea and some small adjoining islets only by a narrow and
shallow strait; whereas New Guinea and its adjoining islets are cut off from
the other East Indian islands by deep water. These latter islands, I may
remark, which fall into the great Asiatic group, are separated from each
other and the continent only by shallow water; and where this is the case we
may suppose, from geological oscillations of level, that generally there has
been recent union. South America, including the southern part of Mexico, is
cut off from North America by the West Indies, and the great table-land of
Mexico, except by a mere fringe of tropical forests along the coast: it is
owing, perhaps, to this fringe that N. America possesses some S. American
forms. Madagascar is entirely isolated. Africa is also to a great extent
isolated, although it approaches, by many promontories and by lines of
shallower sea, to Europe and Asia: southern Africa, which is the most
distinct in its mammiferous inhabitants, is separated from the northern
portion by the Great Sahara Desert and the table-land of Abyssinia. That the
distribution of organisms is related to barriers, stopping their progress, we
clearly see by comparing the distribution of marine and terrestrial
productions. The marine animals being different on the two sides of land
tenanted by the same terrestrial animals, thus the shells are wholly different
on the opposite sides of the temperate parts of South America{346}, as they
are «?» in the Red Sea and the Mediterranean. We can at once perceive that
the destruction of a barrier would permit two geographical groups of
organisms to fuse and blend into one. But the original cause of groups being
different on opposite sides of a barrier can only be understood on the
hypothesis of each organism having been created or produced on one spot
or area, and afterwards migrating as widely as its means of transport and
subsistence permitted it.

Relation of range in genera and species.
It is generally{347} found, that where a genus or group ranges over nearly
the entire world, many of the species composing the group have wide
ranges: on the other hand, where a group is restricted to any one country,
the species composing it generally have restricted ranges in that country{348}.

Thus among mammifers the feline and canine genera are widely distributed,
and many of the individual species have enormous ranges [the genus Mus I
believe, however, is a strong exception to the rule]. Mr Gould informs me
that the rule holds with birds, as in the owl genus, which is mundane, and
many of the species range widely. The rule holds also with land and fresh-
water mollusca, with butterflies and very generally with plants. As instances
of the converse rule, I may give that division of the monkeys which is
confined to S. America, and amongst plants, the Cacti, confined to the same
continent, the species of both of which have generally narrow ranges. On
the ordinary theory of the separate creation of each species, the cause of
these relations is not obvious; we can see no reason, because many allied
species have been created in the several main divisions of the world, that
several of these species should have wide ranges; and on the other hand,
that species of the same group should have narrow ranges if all have been
created in one main division of the world. As the result of such and
probably many other unknown relations, it is found that, even in the same
great classes of beings, the different divisions of the world are characterised
by either merely different species, or genera, or even families: thus in cats,
mice, foxes, S. America differs from Asia and Africa only in species; in her
pigs, camels and monkeys the difference is generic or greater. Again, whilst
southern Africa and Australia differ more widely in their mammalia than do
Africa and S. America, they are more closely (though indeed very distantly)
allied in their plants.

Distribution of the inhabitants in the same continent.
If we now look at the distribution of the organisms in any one of the
above main divisions of the world, we shall find it split up into many
regions, with all or nearly all their species distinct, but yet partaking of one
common character. This similarity of type in the subdivisions of a great
region is equally well-known with the dissimilarity of the inhabitants of the
several great regions; but it has been less often insisted on, though more
worthy of remark. Thus for instance, if in Africa or S. America, we go from
south to north{349}, or from lowland to upland, or from a humid to a dryer
part, we find wholly different species of those genera or groups which
characterise the continent over which we are passing. In these subdivisions
we may clearly observe, as in the main divisions of the world, that sub-
barriers divide different groups of species, although the opposite sides of

such sub-barriers may possess nearly the same climate, and may be in other
respects nearly similar: thus it is on the opposite sides of the Cordillera of
Chile, and in a lesser degree on the opposite sides of the Rocky mountains.
Deserts, arms of the sea, and even rivers form the barriers; mere
preoccupied space seems sufficient in several cases: thus Eastern and
Western Australia, in the same latitude, with very similar climate and soils,
have scarcely a plant, and few animals or birds, in common, although all
belong to the peculiar genera characterising Australia. It is in short
impossible to explain the differences in the inhabitants, either of the main
divisions of the world, or of these sub-divisions, by the differences in their
physical conditions, and by the adaptation of their inhabitants. Some other
cause must intervene.
We can see that the destruction of sub-barriers would cause (as before
remarked in the case of the main divisions) two sub-divisions to blend into
one; and we can only suppose that the original difference in the species, on
the opposite sides of sub-barriers, is due to the creation or production of
species in distinct areas, from which they have wandered till arrested by
such sub-barriers. Although thus far is pretty clear, it may be asked, why,
when species in the same main division of the world were produced on
opposite sides of a sub-barrier, both when exposed to similar conditions and
when exposed to widely different influences (as on alpine and lowland
tracts, as on arid and humid soils, as in cold and hot climates), have they
invariably been formed on a similar type, and that type confined to this one
division of the world? Why when an ostrich{350} was produced in the
southern parts of America, was it formed on the American type, instead of
on the African or on Australian types? Why when hare-like and rabbit-like
animals were formed to live on the Savannahs of La Plata, were they
produced on the peculiar Rodent type of S. America, instead of on the
true{351} hare-type of North America, Asia and Africa? Why when borrowing
Rodents, and camel-like animals were formed to tenant the Cordillera, were
they formed on the same type{352} with their representatives on the plains?
Why were the mice, and many birds of different species on the opposite
sides of the Cordillera, but exposed to a very similar climate and soil,
created on the same peculiar S. American type? Why were the plants in
Eastern and Western Australia, though wholly different as species, formed
on the same peculiar Australian types? The generality of the rule, in so

many places and under such different circumstances, makes it highly
remarkable and seems to demand some explanation.

Insular Faunas.
If we now look to the character of the inhabitants of small islands{353},
we shall find that those situated close to other land have a similar fauna
with that land{354}, whilst those at a considerable distance from other land
often possess an almost entirely peculiar fauna. The Galapagos
Archipelago{355} is a remarkable instance of this latter fact; here almost
every bird, its one mammifer, its reptiles, land and sea shells, and even fish,
are almost all peculiar and distinct species, not found in any other quarter of
the world: so are the majority of its plants. But although situated at the
distance of between 500 and 600 miles from the S. American coast, it is
impossible to even glance at a large part of its fauna, especially at the birds,
without at once seeing that they belong to the American type{356}. Hence, in
fact, groups of islands thus circumstanced form merely small but well-
defined sub-divisions of the larger geographical divisions. But the fact is in
such cases far more striking: for taking the Galapagos Archipelago as an
instance; in the first place we must feel convinced, seeing that every island
is wholly volcanic and bristles with craters, that in a geological sense the
whole is of recent origin comparatively with a continent; and as the species
are nearly all peculiar, we must conclude that they have in the same sense
recently been produced on this very spot; and although in the nature of the
soil, and in a lesser degree in the climate, there is a wide difference with the
nearer part of the S. American coast, we see that the inhabitants have been
formed on the same closely allied type. On the other hand, these islands, as
far as their physical conditions are concerned, resemble closely the Cape de
Verde volcanic group, and yet how wholly unlike are the productions of
these two archipelagoes. The Cape de Verde{357} group, to which may be
added the Canary Islands, are allied in their inhabitants (of which many are
peculiar species) to the coast of Africa and southern Europe, in precisely the
same manner as the Galapagos Archipelago is allied to America. We here
clearly see that mere geographical proximity affects, more than any relation
of adaptation, the character of species. How many islands in the Pacific
exist far more like in their physical conditions to Juan Fernandez than this
island is to the coast of Chile, distant 300 miles; why then, except from
mere proximity, should this island alone be tenanted by two very peculiar

species of humming-birds—that form of birds which is so exclusively
American? Innumerable other similar cases might be adduced.
The Galapagos Archipelago offers another, even more remarkable,
example of the class of facts we are here considering. Most of its genera
are, as we have said, American, many of them are mundane, or found
everywhere, and some are quite or nearly confined to this archipelago. The
islands are of absolutely similar composition, and exposed to the same
climate; most of them are in sight of each other; and yet several of the
islands are inhabited, each by peculiar species (or in some cases perhaps
only varieties) of some of the genera characterising the archipelago. So that
the small group of the Galapagos Islands typifies, and follows exactly the
same laws in the distribution of its inhabitants, as a great continent. How
wonderful it is that two or three closely similar but distinct species of a
mocking-thrush{358} should have been produced on three neighbouring and
absolutely similar islands; and that these three species of mocking-thrush
should be closely related to the other species inhabiting wholly different
climates and different districts of America, and only in America. No similar
case so striking as this of the Galapagos Archipelago has hitherto been
observed; and this difference of the productions in the different islands may
perhaps be partly explained by the depth of the sea between them (showing
that they could not have been united within recent geological periods), and
by the currents of the sea sweeping straight between them,—and by storms
of wind being rare, through which means seeds and birds could be blown,
or drifted, from one island to another. There are however some similar facts:
it is said that the different, though neighbouring islands of the East Indian
Archipelago are inhabited by some different species of the same genera;
and at the Sandwich group some of the islands have each their peculiar
species of the same genera of plants.
Islands standing quite isolated within the intra-tropical oceans have
generally very peculiar floras, related, though feebly (as in the case of St
Helena{359} where almost every species is distinct), with the nearest
continent: Tristan d'Acunha is feebly related, I believe, in its plants, both to
Africa and S. America, not by having species in common, but by the genera
to which they belong{360}. The floras of the numerous scattered islands of
the Pacific are related to each other and to all the surrounding continents;
but it has been said, that they have more of an Indo-Asiatic than American

character{361}. This is somewhat remarkable, as America is nearer to all the
Eastern islands, and lies in the direction of the trade-wind and prevailing
currents; on the other hand, all the heaviest gales come from the Asiatic
side. But even with the aid of these gales, it is not obvious on the ordinary
theory of creation how the possibility of migration (without we suppose,
with extreme improbability, that each species with an Indo-Asiatic character
has actually travelled from the Asiatic shores, where such species do not
now exist) explains this Asiatic character in the plants of the Pacific. This is
no more obvious than that (as before remarked) there should exist a relation
between the creation of closely allied species in several regions of the
world, and the fact of many such species having wide ranges; and on the
other hand, of allied species confined to one region of the world having in
that region narrow ranges.

Alpine Floras.
We will now turn to the floras of mountain-summits which are well
known to differ from the floras of the neighbouring lowlands. In certain
characters, such as dwarfness of stature, hairiness, &c., the species from the
most distant mountains frequently resemble each other,—a kind of analogy
like that for instance of the succulency of most desert plants. Besides this
analogy, Alpine plants present some eminently curious facts in their
distribution. In some cases the summits of mountains, although immensely
distant from each other, are clothed by the same identical species{362} which
are likewise the same with those growing on the likewise very distant Arctic
shores. In other cases, although few or none of the species may be actually
identical, they are closely related; whilst the plants of the lowland districts
surrounding the two mountains in question will be wholly dissimilar. As
mountain-summits, as far as their plants are concerned, are islands rising
out of an ocean of land in which the Alpine species cannot live, nor across
which is there any known means of transport, this fact appears directly
opposed to the conclusion which we have come to from considering the
general distribution of organisms both on continents and on islands—
namely, that the degree of relationship between the inhabitants of two
points depends on the completeness and nature of the barriers between
those points{363}. I believe, however, this anomalous case admits, as we shall
presently see, of some explanation. We might have expected that the flora
of a mountain summit would have presented the same relation to the flora

of the surrounding lowland country, which any isolated part of a continent
does to the whole, or an island does to the mainland, from which it is
separated by a rather wide space of sea. This in fact is the case with the
plants clothing the summits of some mountains, which mountains it may be
observed are particularly isolated; for instance, all the species are peculiar,
but they belong to the forms characteristic of the surrounding continent, on
the mountains of Caraccas, of Van Dieman's Land and of the Cape of Good
Hope{364}. On some other mountains, for instance «in» Tierra del Fuego and
in Brazil, some of the plants though distinct species are S. American forms;
whilst others are allied to or are identical with the Alpine species of Europe.
In islands of which the lowland flora is distinct «from» but allied to that of
the nearest continent, the Alpine plants are sometimes (or perhaps mostly)
eminently peculiar and distinct{365}; this is the case on Teneriffe, and in a
lesser degree even on some of the Mediterranean islands.
If all Alpine floras had been characterised like that of the mountain of
Caraccas, or of Van Dieman’s Land, &c., whatever explanation is possible
of the general laws of geographical distribution would have applied to
them. But the apparently anomalous case just given, namely of the
mountains of Europe, of some mountains in the United States (Dr Boott)
and of the summits of the Himalaya (Royle), having many identical species
in common conjointly with the Arctic regions, and many species, though
not identical, closely allied, require a separate explanation. The fact
likewise of several of the species on the mountains of Tierra del Fuego (and
in a lesser degree on the mountains of Brazil) not belonging to American
forms, but to those of Europe, though so immensely remote, requires also a
separate explanation.

Cause of the similarity in the floras of some distant mountains.
Now we may with confidence affirm, from the number of the then
floating icebergs and low descent of the glaciers, that within a period so
near that species of shells have remained the same, the whole of Central
Europe and of North America (and perhaps of Eastern Asia) possessed a
very cold climate; and therefore it is probable that the floras of these
districts were the same as the present Arctic one,—as is known to have been
to some degree the case with then existing sea-shells, and those now living
on the Arctic shores. At this period the mountains must have been covered

with ice of which we have evidence in the surfaces polished and scored by
glaciers. What then would be the natural and almost inevitable effects of the
gradual change into the present more temperate climate{366}? The ice and
snow would disappear from the mountains, and as new plants from the
more temperate regions of the south migrated northward, replacing the
Arctic plants, these latter would crawl{367} up the now uncovered mountains,
and likewise be driven northward to the present Arctic shores. If the Arctic
flora of that period was a nearly uniform one, as the present one is, then we
should have the same plants on these mountain-summits and on the present
Arctic shores. On this view the Arctic flora of that period must have been a
widely extended one, more so than even the present one; but considering
how similar the physical conditions must always be of land bordering on
perpetual frost, this does not appear a great difficulty; and may we not
venture to suppose that the almost infinitely numerous icebergs, charged
with great masses of rocks, soil and brushwood{368} and often driven high up
on distant beaches, might have been the means of widely distributing the
seeds of the same species?
I will only hazard one other observation, namely that during the change
from an extremely cold climate to a more temperate one the conditions,
both on lowland and mountain, would be singularly favourable for the
diffusion of any existing plants, which could live on land, just freed from
the rigour of eternal winter; for it would possess no inhabitants; and we
cannot doubt that preoccupation{369} is the chief bar to the diffusion of
plants. For amongst many other facts, how otherwise can we explain the
circumstance that the plants on the opposite, though similarly constituted
sides of a wide river in Eastern Europe (as I was informed by Humboldt)
should be widely different; across which river birds, swimming quadrupeds
and the wind must often transport seeds; we can only suppose that plants
already occupying the soil and freely seeding check the germination of
occasionally transported seeds.
At about the same period when icebergs were transporting boulders in
N. America as far as 36° south, where the cotton tree now grows in South
America, in latitude 42° (where the land is now clothed with forests having
an almost tropical aspect with the trees bearing epiphytes and intertwined
with canes), the same ice action was going on; is it not then in some degree
probable that at this period the whole tropical parts of the two Americas

possessed{370} (as Falconer asserts that India did) a more temperate climate?
In this case the Alpine plants of the long chain of the Cordillera would have
descended much lower and there would have been a broad high-road{371}
connecting those parts of North and South America which were then frigid.
As the present climate supervened, the plants occupying the districts which
now are become in both hemispheres temperate and even semi-tropical
must have been driven to the Arctic and Antarctic{372} regions; and only a
few of the loftiest points of the Cordillera can have retained their former
connecting flora. The transverse chain of Chiquitos might perhaps in a
similar manner during the ice-action period have served as a connecting
road (though a broken one) for Alpine plants to become dispersed from the
Cordillera to the highlands of Brazil. It may be observed that some (though
not strong) reasons can be assigned for believing that at about this same
period the two Americas were not so thoroughly divided as they now are by
the West Indies and tableland of Mexico. I will only further remark that the
present most singularly close similarity in the vegetation of the lowlands of
Kerguelen’s Land{373} and of Tierra del Fuego (Hooker), though so far apart,
may perhaps be explained by the dissemination of seeds during this same
cold period, by means of icebergs, as before alluded to{374}.
Finally, I think we may safely grant from the foregoing facts and
reasoning that the anomalous similarity in the vegetation of certain very
distant mountain-summits is not in truth opposed to the conclusion of the
intimate relation subsisting between proximity in space (in accordance with
the means of transport in each class) and the degree of affinity of the
inhabitants of any two countries. In the case of several quite isolated
mountains, we have seen that the general law holds good.

Whether the same species has been created more than once.
As the fact of the same species of plants having been found on
mountain-summits immensely remote has been one chief cause of the belief
of some species having been contemporaneously produced or created at two
different points{375}, I will here briefly discuss this subject. On the ordinary
theory of creation, we can see no reason why on two similar mountain-
summits two similar species may not have been created; but the opposite
view, independently of its simplicity, has been generally received from the
analogy of the general distribution of all organisms, in which (as shown in
this chapter) we almost always find that great and continuous barriers
separate distinct series; and we are naturally led to suppose that the two
series have been separately created. When taking a more limited view we
see a river, with a quite similar country on both sides, with one side well
stocked with a certain animal and on the other side not one (as is the case
with the Bizcacha{376} on the opposite sides of the Plata), we are at once led
to conclude that the Bizcacha was produced on some one point or area on
the western side of the river. Considering our ignorance of the many strange
chances of diffusion by birds (which occasionally wander to immense
distances) and quadrupeds swallowing seeds and ova (as in the case of the
flying water-beetle which disgorged the eggs of a fish), and of whirlwinds
carrying seeds and animals into strong upper currents (as in the case of
volcanic ashes and showers of hay, grain and fish{377}), and of the possibility
of species having survived for short periods at intermediate spots and
afterwards becoming extinct there{378}; and considering our knowledge of
the great changes which have taken place from subsidence and elevation in
the surface of the earth, and of our ignorance of the greater changes which
may have taken place, we ought to be very slow in admitting the probability
of double creations. In the case of plants on mountain-summits, I think I
have shown how almost necessarily they would, under the past conditions
of the northern hemisphere, be as similar as are the plants on the present
Arctic shores; and this ought to teach us a lesson of caution.
But the strongest argument against double creations may be drawn from
considering the case of mammifers{379} in which, from their nature and from
the size of their offspring, the means of distribution are more in view. There
are no cases where the same species is found in very remote localities,
except where there is a continuous belt of land: the Arctic region perhaps

offers the strongest exception, and here we know that animals are
transported on icebergs{380}. The cases of lesser difficulty may all receive a
more or less simple explanation; I will give only one instance; the
nutria{381}, I believe, on the eastern coast of S. America live exclusively in
fresh-water rivers, and I was much surprised how they could have got into
rivulets, widely apart, on the coast of Patagonia; but on the opposite coast I
found these quadrupeds living exclusively in the sea, and hence their
migration along the Patagonian coast is not surprising. There is no case of
the same mammifer being found on an island far from the coast, and on the
mainland, as happens with plants{382}. On the idea of double creations it
would be strange if the same species of several plants should have been
created in Australia and Europe; and no one instance of the same species of
mammifer having been created, or aboriginally existing, in two as nearly
remote and equally isolated points. It is more philosophical, in such cases,
as that of some plants being found in Australia and Europe, to admit that we
are ignorant of the means of transport. I will allude only to one other case,
namely, that of the Mydas{383}, an Alpine animal, found only on the distant
peaks of the mountains of Java: who will pretend to deny that during the ice
period of the northern and southern hemispheres, and when India is
believed to have been colder, the climate might not have permitted this
animal to haunt a lower country, and thus to have passed along the ridges
from summit to summit? Mr Lyell has further observed that, as in space, so
in time, there is no reason to believe that after the extinction of a species,
the self-same form has ever reappeared{384}. I think, then, we may,
notwithstanding the many cases of difficulty, conclude with some
confidence that every species has been created or produced on a single
point or area.

On the number of species, and of the classes to which they belong
in different regions.
The last fact in geographical distribution, which, as far as I can see, in
any way concerns the origin of species, relates to the absolute number and
nature of the organic beings inhabiting different tracts of land. Although
every species is admirably adapted (but not necessarily better adapted than
every other species, as we have seen in the great increase of introduced
species) to the country and station it frequents; yet it has been shown that

the entire difference between the species in distant countries cannot
possibly be explained by the difference of the physical conditions of these
countries. In the same manner, I believe, neither the number of the species,
nor the nature of the great classes to which they belong, can possibly in all
cases be explained by the conditions of their country. New Zealand{385}, a
linear island stretching over about 700 miles of latitude, with forests,
marshes, plains and mountains reaching to the limits of eternal snow, has
far more diversified habitats than an equal area at the Cape of Good Hope;
and yet, I believe, at the Cape of Good Hope there are, of phanerogamic
plants, from five to ten times the number of species as in all New Zealand.
Why on the theory of absolute creations should this large and diversified
island only have from 400 to 500 (? Dieffenbach) phanerogamic plants? and
why should the Cape of Good Hope, characterised by the uniformity of its
scenery, swarm with more species of plants than probably any other quarter
of the world? Why on the ordinary theory should the Galapagos Islands
abound with terrestrial reptiles? and why should many equal-sized islands
in the Pacific be without a single one{386} or with only one or two species?
Why should the great island of New Zealand be without one mammiferous
quadruped except the mouse, and that was probably introduced with the
aborigines? Why should not one island (it can be shown, I think, that the
mammifers of Mauritius and St Iago have all been introduced) in the open
ocean possess a mammiferous quadruped? Let it not be said that
quadrupeds cannot live in islands, for we know that cattle, horses and pigs
during a long period have run wild in the West Indian and Falkland Islands;
pigs at St Helena; goats at Tahiti; asses in the Canary Islands; dogs in Cuba;
cats at Ascension; rabbits at Madeira and the Falklands; monkeys at St Iago
and the Mauritius; even elephants during a long time in one of the very
small Sooloo Islands; and European mice on very many of the smallest
islands far from the habitations of man{387}. Nor let it be assumed that
quadrupeds are more slowly created and hence that the oceanic islands,
which generally are of volcanic formation, are of too recent origin to
possess them; for we know (Lyell) that new forms of quadrupeds succeed
each other quicker than Mollusca or Reptilia. Nor let it be assumed (though
such an assumption would be no explanation) that quadrupeds cannot be
created on small islands; for islands not lying in mid-ocean do possess their
peculiar quadrupeds; thus many of the smaller islands of the East Indian
Archipelago possess quadrupeds; as does Fernando Po on the West Coast of

Africa; as the Falkland Islands possess a peculiar wolf-like fox{388}; so do
the Galapagos Islands a peculiar mouse of the S. American type. These two
last are the most remarkable cases with which I am acquainted; inasmuch as
the islands lie further from other land. It is possible that the Galapagos
mouse may have been introduced in some ship from the S. American coast
(though the species is at present unknown there), for the aboriginal species
soon haunts the goods of man, as I noticed in the roof of a newly erected
shed in a desert country south of the Plata. The Falkland Islands, though
between 200 and 300 miles from the S. American coast, may in one sense
be considered as intimately connected with it; for it is certain that formerly
many icebergs loaded with boulders were stranded on its southern coast,
and the old canoes which are occasionally now stranded, show that the
currents still set from Tierra del Fuego. This fact, however, does not explain
the presence of the Canis antarcticus on the Falkland Islands, unless we
suppose that it formerly lived on the mainland and became extinct there,
whilst it survived on these islands, to which it was borne (as happens with
its northern congener, the common wolf) on an iceberg, but this fact
removes the anomaly of an island, in appearance effectually separated from
other land, having its own species of quadruped, and makes the case like
that of Java and Sumatra, each having their own rhinoceros.
Before summing up all the facts given in this section on the present
condition of organic beings, and endeavouring to see how far they admit of
explanation, it will be convenient to state all such facts in the past
geographical distribution of extinct beings as seem anyway to concern the
theory of descent.

Section Second.
Geographical distribution of extinct organisms.
I have stated that if the land of the entire world be divided into (we will
say) three sections, according to the amount of difference of the terrestrial
mammifers inhabiting them, we shall have three unequal divisions of (1st)
Australia and its dependent islands, (2nd) South America, (3rd) Europe,
Asia and Africa. If we now look to the mammifers which inhabited these
three divisions during the later Tertiary periods, we shall find them almost
as distinct as at the present day, and intimately related in each division to
the existing forms in that division{389}. This is wonderfully the case with the

several fossil Marsupial genera in the caverns of New South Wales and
even more wonderfully so in South America, where we have the same
peculiar group of monkeys, of a guanaco-like animal, of many rodents, of
the Marsupial Didelphys, of Armadilloes and other Edentata. This last
family is at present very characteristic of S. America, and in a late Tertiary
epoch it was even more so, as is shown by the numerous enormous animals
of the Megatheroid family, some of which were protected by an osseous
armour like that, but on a gigantic scale, of the recent Armadillo. Lastly,
over Europe the remains of the several deer, oxen, bears, foxes, beavers,
field-mice, show a relation to the present inhabitants of this region; and the
contemporaneous remains of the elephant, rhinoceros, hippopotamus,
hyæna, show a relation with the grand Africo-Asiatic division of the world.
In Asia the fossil mammifers of the Himalaya (though mingled with forms
long extinct in Europe) are equally related to the existing forms of the
Africo-Asiatic division; but especially to those of India itself. As the
gigantic and now extinct quadrupeds of Europe have naturally excited more
attention than the other and smaller remains, the relation between the past
and the present mammiferous inhabitants of Europe has not been
sufficiently attended to. But in fact the mammifers of Europe are at present
nearly as much Africo-Asiatic as they were formerly when Europe had its
elephants and rhinoceroses, etc.; Europe neither now nor then possessed
peculiar groups as does Australia and S. America. The extinction of certain
peculiar forms in one quarter does not make the remaining mammifers of
that quarter less related to its own great division of the world: though Tierra
del Fuego possesses only a fox, three rodents, and the guanaco, no one (as
these all belong to S. American types, but not to the most characteristic
forms) would doubt for one minute «as to» classifying this district with S.
America; and if fossil Edentata, Marsupials and monkeys were to be found
in Tierra del Fuego, it would not make this district more truly S. American
than it now is. So it is with Europe{390}, and so far as is known with Asia, for
the lately past and present mammifers all belong to the Africo-Asiatic
division of the world. In every case, I may add, the forms which a country
has is of more importance in geographical arrangement than what it has not.
We find some evidence of the same general fact in a relation between
the recent and the Tertiary sea-shells, in the different main divisions of the
marine world.

This general and most remarkable relation between the lately past and
present mammiferous inhabitants of the three main divisions of the world is
precisely the same kind of fact as the relation between the different species
of the several sub-regions of any one of the main divisions. As we usually
associate great physical changes with the total extinction of one series of
beings, and its succession by another series, this identity of relation between
the past and the present races of beings in the same quarters of the globe is
more striking than the same relation between existing beings in different
sub-regions: but in truth we have no reason for supposing that a change in
the conditions has in any of these cases supervened, greater than that now
existing between the temperate and tropical, or between the highlands and
lowlands of the same main divisions, now tenanted by related beings.
Finally, then, we clearly see that in each main division of the world the
same relation holds good between its inhabitants in time as over space{391}.

Changes in geographical distribution.
If, however, we look closer, we shall find that even Australia, in
possessing a terrestrial Pachyderm, was so far less distinct from the rest of
the world than it now is; so was S. America in possessing the Mastodon,
horse, [hyæna,]{392} and antelope. N. America, as I have remarked, is now, in
its mammifers, in some respects neutral ground between S. America and the
great Africo-Asiatic division; formerly, in possessing the horse, Mastodon
and three Megatheroid animals, it was more nearly related to S. America;
but in the horse and Mastodon, and likewise in having the elephant, oxen,
sheep, and pigs, it was as much, if not more, related to the Africo-Asiatic
division. Again, northern India was much more closely related (in having
the giraffe, hippopotamus, and certain musk-deer) to southern Africa than it
now is; for southern and eastern Africa deserve, if we divide the world into
five parts, to make one division by itself. Turning to the dawn of the
Tertiary period, we must, from our ignorance of other portions of the world,
confine ourselves to Europe; and at that period, in the presence of
Marsupials{393} and Edentata, we behold an entire blending of those
mammiferous forms which now eminently characterise Australia and S.
America{394}.
If we now look at the distribution of sea-shells, we find the same
changes in distribution. The Red Sea and the Mediterranean were more

nearly related in these shells than they now are. In different parts of Europe,
on the other hand, during the Miocene period, the sea-shells seem to have
been more different than at present. In{395} the Tertiary period, according to
Lyell, the shells of N. America and Europe were less related than at present,
and during the Cretaceous still less like; whereas, during this same
Cretaceous period, the shells of India and Europe were more like than at
present. But going further back to the Carbonaceous period, in N. America
and Europe, the productions were much more like than they now are{396}.
These facts harmonise with the conclusions drawn from the present
distribution of organic beings, for we have seen, that from species being
created in different points or areas, the formation of a barrier would cause
or make two distinct geographical areas; and the destruction of a barrier
would permit their diffusion{397}. And as long-continued geological changes
must both destroy and make barriers, we might expect, the further we
looked backwards, the more changed should we find the present
distribution. This conclusion is worthy of attention; because, finding in
widely different parts of the same main division of the world, and in
volcanic islands near them, groups of distinct, but related, species;—and
finding that a singularly analogous relation holds good with respect to the
beings of past times, when none of the present species were living, a person
might be tempted to believe in some mystical relation between certain areas
of the world, and the production of certain organic forms; but we now see
that such an assumption would have to be complicated by the admission
that such a relation, though holding good for long revolutions of years, is
not truly persistent.
I will only add one more observation to this section. Geologists finding
in the most remote period with which we are acquainted, namely in the
Silurian period, that the shells and other marine productions{398} in North
and South America, in Europe, Southern Africa, and Western Asia, are
much more similar than they now are at these distant points, appear to have
imagined that in these ancient times the laws of geographical distribution
were quite different than what they now are: but we have only to suppose
that great continents were extended east and west, and thus did not divide
the inhabitants of the temperate and tropical seas, as the continents now do;
and it would then become probable that the inhabitants of the seas would be
much more similar than they now are. In the immense space of ocean

extending from the east coast of Africa to the eastern islands of the Pacific,
which space is connected either by lines of tropical coast or by islands not
very distant from each other, we know (Cuming) that many shells, perhaps
even as many as 200, are common to the Zanzibar coast, the Philippines,
and the eastern islands of the Low or Dangerous Archipelago in the Pacific.
This space equals that from the Arctic to the Antarctic pole! Pass over the
space of quite open ocean, from the Dangerous Archipelago to the west
coast of S. America, and every shell is different: pass over the narrow space
of S. America, to its eastern shores, and again every shell is different! Many
fish, I may add, are also common to the Pacific and Indian Oceans.

Summary on the distribution of living and extinct organic beings.
Let us sum up the several facts now given with respect to the past and
present geographical distribution of organic beings. In a previous chapter it
was shown that species are not exterminated by universal catastrophes, and
that they are slowly produced: we have also seen that each species is
probably only once produced, on one point or area once in time; and that
each diffuses itself, as far as barriers and its conditions of life permit. If we
look at any one main division of the land, we find in the different parts,
whether exposed to different conditions or to the same conditions, many
groups of species wholly or nearly distinct as species, nevertheless
intimately related. We find the inhabitants of islands, though distinct as
species, similarly related to the inhabitants of the nearest continent; we find
in some cases, that even the different islands of one such group are
inhabited by species distinct, though intimately related to one another and
to those of the nearest continent:—thus typifying the distribution of organic
beings over the whole world. We find the floras of distant mountain-
summits either very similar (which seems to admit, as shown, of a simple
explanation) or very distinct but related to the floras of the surrounding
region; and hence, in this latter case, the floras of two mountain-summits,
although exposed to closely similar conditions, will be very different. On
the mountain-summits of islands, characterised by peculiar faunas and
floras, the plants are often eminently peculiar. The dissimilarity of the
organic beings inhabiting nearly similar countries is best seen by comparing
the main divisions of the world; in each of which some districts may be
found very similarly exposed, yet the inhabitants are wholly unlike;—far
more unlike than those in very dissimilar districts in the same main

division. We see this strikingly in comparing two volcanic archipelagoes,
with nearly the same climate, but situated not very far from two different
continents; in which case their inhabitants are totally unlike. In the different
main divisions of the world, the amount of difference between the
organisms, even in the same class, is widely different, each main division
having only the species distinct in some families, in other families having
the genera distinct. The distribution of aquatic organisms is very different
from that of the terrestrial organisms; and necessarily so, from the barriers
to their progress being quite unlike. The nature of the conditions in an
isolated district will not explain the number of species inhabiting it; nor the
absence of one class or the presence of another class. We find that terrestrial
mammifers are not present on islands far removed from other land. We see
in two regions, that the species though distinct are more or less related,
according to the greater or less possibility of the transportal in past and
present times of species from one to the other region; although we can
hardly admit that all the species in such cases have been transported from
the first to the second region, and since have become extinct in the first: we
see this law in the presence of the fox on the Falkland Islands; in the
European character of some of the plants of Tierra del Fuego; in the Indo-
Asiatic character of the plants of the Pacific; and in the circumstance of
those genera which range widest having many species with wide ranges;
and those genera with restricted ranges having species with restricted
ranges. Finally, we find in each of the main divisions of the land, and
probably of the sea, that the existing organisms are related to those lately
extinct.
Looking further backwards we see that the past geographical
distribution of organic beings was different from the present; and indeed,
considering that geology shows that all our land was once under water, and
that where water now extends land is forming, the reverse could hardly
have been possible.
Now these several facts, though evidently all more or less connected
together, must by the creationist (though the geologist may explain some of
the anomalies) be considered as so many ultimate facts. He can only say,
that it so pleased the Creator that the organic beings of the plains, deserts,
mountains, tropical and temperature forests, of S. America, should all have
some affinity together; that the inhabitants of the Galapagos Archipelago

should be related to those of Chile; and that some of the species on the
similarly constituted islands of this archipelago, though most closely
related, should be distinct; that all its inhabitants should be totally unlike
those of the similarly volcanic and arid Cape de Verde and Canary Islands;
that the plants on the summit of Teneriffe should be eminently peculiar; that
the diversified island of New Zealand should have not many plants, and not
one, or only one, mammifer; that the mammifers of S. America, Australia
and Europe should be clearly related to their ancient and exterminated
prototypes; and so on with other facts. But it is absolutely opposed to every
analogy, drawn from the laws imposed by the Creator on inorganic matter,
that facts, when connected, should be considered as ultimate and not the
direct consequences of more general laws.

Section Third.
An attempt to explain the foregoing laws of geographical
distribution, on the theory of allied species having a common
descent.
First let us recall the circumstances most favourable for variation under
domestication, as given in the first chapter—viz. 1st, a change, or repeated
changes, in the conditions to which the organism has been exposed,
continued through several seminal (i.e. not by buds or divisions)
generations: 2nd, steady selection of the slight varieties thus generated with
a fixed end in view: 3rd, isolation as perfect as possible of such selected
varieties; that is, the preventing their crossing with other forms; this latter
condition applies to all terrestrial animals, to most if not all plants and
perhaps even to most (or all) aquatic organisms. It will be convenient here
to show the advantage of isolation in the formation of a new breed, by
comparing the progress of two persons (to neither of whom let time be of
any consequence) endeavouring to select and form some very peculiar new
breed. Let one of these persons work on the vast herds of cattle in the plains
of La Plata{399}, and the other on a small stock of 20 or 30 animals in an
island. The latter might have to wait centuries (by the hypothesis of no
importance){400} before he obtained a “sport” approaching to what he
wanted; but when he did and saved the greater number of its offspring and
their offspring again, he might hope that his whole little stock would be in
some degree affected, so that by continued selection he might gain his end.

But on the Pampas, though the man might get his first approach to his
desired form sooner, how hopeless would it be to attempt, by saving its
offspring amongst so many of the common kind, to affect the whole herd:
the effect of this one peculiar “sport{401}” would be quite lost before he
could obtain a second original sport of the same kind. If, however, he could
separate a small number of cattle, including the offspring of the desirable
“sport,” he might hope, like the man on the island, to effect his end. If there
be organic beings of which two individuals never unite, then simple
selection whether on a continent or island would be equally serviceable to
make a new and desirable breed; and this new breed might be made in
surprisingly few years from the great and geometrical powers of
propagation to beat out the old breed; as has happened (notwithstanding
crossing) where good breeds of dogs and pigs have been introduced into a
limited country,—for instance, into the islands of the Pacific.
Let us now take the simplest natural case of an islet upheaved by the
volcanic or subterranean forces in a deep sea, at such a distance from other
land that only a few organic beings at rare intervals were transported to it,
whether borne by the sea{402} (like the seeds of plants to coral-reefs), or by
hurricanes, or by floods, or on rafts, or in roots of large trees, or the germs
of one plant or animal attached to or in the stomach of some other animal,
or by the intervention (in most cases the most probable means) of other
islands since sunk or destroyed. It may be remarked that when one part of
the earth’s crust is raised it is probably the general rule that another part
sinks. Let this island go on slowly, century after century, rising foot by foot;
and in the course of time we shall have instead «of» a small mass of
rock{403}, lowland and highland, moist woods and dry sandy spots, various
soils, marshes, streams and pools: under water on the sea shore, instead of a
rocky steeply shelving coast, we shall have in some parts bays with mud,
sandy beaches and rocky shoals. The formation of the island by itself must
often slightly affect the surrounding climate. It is impossible that the first
few transported organisms could be perfectly adapted to all these stations;
and it will be a chance if those successively transported will be so adapted.
The greater number would probably come from the lowlands of the nearest
country; and not even all these would be perfectly adapted to the new islet
whilst it continued low and exposed to coast influences. Moreover, as it is
certain that all organisms are nearly as much adapted in their structure to

the other inhabitants of their country as they are to its physical conditions,
so the mere fact that a few beings (and these taken in great degree by
chance) were in the first case transported to the islet, would in itself greatly
modify their conditions{404}. As the island continued rising we might also
expect an occasional new visitant; and I repeat that even one new being
must often affect beyond our calculation by occupying the room and taking
part of the subsistence of another (and this again from another and so on),
several or many other organisms. Now as the first transported and any
occasional successive visitants spread or tended to spread over the growing
island, they would undoubtedly be exposed through several generations to
new and varying conditions: it might also easily happen that some of the
species on an average might obtain an increase of food, or food of a more
nourishing quality{405}. According then to every analogy with what we have
seen takes place in every country, with nearly every organic being under
domestication, we might expect that some of the inhabitants of the island
would “sport,” or have their organization rendered in some degree plastic.
As the number of the inhabitants are supposed to be few and as all these
cannot be so well adapted to their new and varying conditions as they were
in their native country and habitat, we cannot believe that every place or
office in the economy of the island would be as well filled as on a continent
where the number of aboriginal species is far greater and where they
consequently hold a more strictly limited place. We might therefore expect
on our island that although very many slight variations were of no use to the
plastic individuals, yet that occasionally in the course of a century an
individual might be born{406} of which the structure or constitution in some
slight degree would allow it better to fill up some office in the insular
economy and to struggle against other species. If such were the case the
individual and its offspring would have a better chance of surviving and of
beating out its parent form; and if (as is probable) it and its offspring
crossed with the unvaried parent form, yet the number of the individuals
being not very great, there would be a chance of the new and more
serviceable form being nevertheless in some slight degree preserved. The
struggle for existence would go on annually selecting such individuals until
a new race or species was formed. Either few or all the first visitants to the
island might become modified, according as the physical conditions of the
island and those resulting from the kind and number of other transported
species were different from those of the parent country—according to the

difficulties offered to fresh immigration—and according to the length of
time since the first inhabitants were introduced. It is obvious that whatever
was the country, generally the nearest from which the first tenants were
transported, they would show an affinity, even if all had become modified,
to the natives of that country and even if the inhabitants of the same source
«?» had been modified. On this view we can at once understand the cause
and meaning of the affinity of the fauna and flora of the Galapagos Islands
with that of the coast of S. America; and consequently why the inhabitants
of these islands show not the smallest affinity with those inhabiting other
volcanic islands, with a very similar climate and soil, near the coast of
Africa{407}.
To return once again to our island, if by the continued action of the
subterranean forces other neighbouring islands were formed, these would
generally be stocked by the inhabitants of the first island, or by a few
immigrants from the neighbouring mainland; but if considerable obstacles
were interposed to any communication between the terrestrial productions
of these islands, and their conditions were different (perhaps only by the
number of different species on each island), a form transported from one
island to another might become altered in the same manner as one from the
continent; and we should have several of the islands tenanted by
representative races or species, as is so wonderfully the case with the
different islands of the Galapagos Archipelago. As the islands become
mountainous, if mountain-species were not introduced, as could rarely
happen, a greater amount of variation and selection would be requisite to
adapt the species, which originally came from the lowlands of the nearest
continent, to the mountain-summits than to the lower districts of our
islands. For the lowland species from the continent would have first to
struggle against other species and other conditions on the coast-land of the
island, and so probably become modified by the selection of its best fitted
varieties, then to undergo the same process when the land had attained a
moderate elevation; and then lastly when it had become Alpine. Hence we
can understand why the faunas of insular mountain-summits are, as in the
case of Teneriffe, eminently peculiar. Putting on one side the case of a
widely extended flora being driven up the mountain-summits, during a
change of climate from cold to temperate, we can see why in other cases the
floras of mountain-summits (or as I have called them islands in a sea of

land) should be tenanted by peculiar species, but related to those of the
surrounding lowlands, as are the inhabitants of a real island in the sea to
those of the nearest continent{408}.
Let us now consider the effect of a change of climate or of other
conditions on the inhabitants of a continent and of an isolated island
without any great change of level. On a continent the chief effects would be
changes in the numerical proportion of the individuals of the different
species; for whether the climate became warmer or colder, drier or damper,
more uniform or extreme, some species are at present adapted to its
diversified districts; if for instance it became cooler, species would migrate
from its more temperate parts and from its higher land; if damper, from its
damper regions, &c. On a small and isolated island, however, with few
species, and these not adapted to much diversified conditions, such changes
instead of merely increasing the number of certain species already adapted
to such conditions, and decreasing the number of other species, would be
apt to affect the constitutions of some of the insular species: thus if the
island became damper it might well happen that there were no species
living in any part of it adapted to the consequences resulting from more
moisture. In this case therefore, and still more (as we have seen) during the
production of new stations from the elevation of the land, an island would
be a far more fertile source, as far as we can judge, of new specific forms
than a continent. The new forms thus generated on an island, we might
expect, would occasionally be transported by accident, or through long-
continued geographical changes be enabled to emigrate and thus become
slowly diffused.
But if we look to the origin of a continent; almost every geologist will
admit that in most cases it will have first existed as separate islands which
gradually increased in size{409}; and therefore all that which has been said
concerning the probable changes of the forms tenanting a small archipelago
is applicable to a continent in its early state. Furthermore, a geologist who
reflects on the geological history of Europe (the only region well known)
will admit that it has been many times depressed, raised and left stationary.
During the sinking of a continent and the probable generally accompanying
changes of climate the effect would be little, except on the numerical
proportions and in the extinction (from the lessening of rivers, the drying of
marshes and the conversion of high-lands into low &c.) of some or of many

of the species. As soon however as the continent became divided into many
isolated portions or islands, preventing free immigration from one part to
another, the effect of climatic and other changes on the species would be
greater. But let the now broken continent, forming isolated islands, begin to
rise and new stations thus to be formed, exactly as in the first case of the
upheaved volcanic islet, and we shall have equally favourable conditions
for the modification of old forms, that is the formation of new races or
species. Let the islands become reunited into a continent; and then the new
and old forms would all spread, as far as barriers, the means of transportal,
and the preoccupation of the land by other species, would permit. Some of
the new species or races would probably become extinct, and some perhaps
would cross and blend together. We should thus have a multitude of forms,
adapted to all kinds of slightly different stations, and to diverse groups of
either antagonist or food-serving species. The oftener these oscillations of
level had taken place (and therefore generally the older the land) the greater
the number of species «which» would tend to be formed. The inhabitants of
a continent being thus derived in the first stage from the same original
parents, and subsequently from the inhabitants of one wide area, since often
broken up and reunited, all would be obviously related together and the
inhabitants of the most dissimilar stations on the same continent would be
more closely allied than the inhabitants of two very similar stations on two
of the main divisions of the world{410}.
I need hardly point out that we now can obviously see why the number
of species in two districts, independently of the number of stations in such
districts, should be in some cases as widely different as in New Zealand and
the Cape of Good Hope{411}. We can see, knowing the difficulty in the
transport of terrestrial mammals, why islands far from mainlands do not
possess them{412}; we see the general reason, namely accidental transport
(though not the precise reason), why certain islands should, and others
should not, possess members of the class of reptiles. We can see why an
ancient channel of communication between two distant points, as the
Cordillera probably was between southern Chile and the United States
during the former cold periods; and icebergs between the Falkland Islands
and Tierra del Fuego; and gales, at a former or present time, between the
Asiatic shores of the Pacific and eastern islands in this ocean; is connected
with (or we may now say causes) an affinity between the species, though

distinct, in two such districts. We can see how the better chance of
diffusion, from several of the species of any genus having wide ranges in
their own countries, explains the presence of other species of the same
genus in other countries{413}; and on the other hand, of species of restricted
powers of ranging, forming genera with restricted ranges.
As every one would be surprised if two exactly similar but peculiar
varieties{414} of any species were raised by man by long continued selection,
in two different countries, or at two very different periods, so we ought not
to expect that an exactly similar form would be produced from the
modification of an old one in two distinct countries or at two distinct
periods. For in such places and times they would probably be exposed to
somewhat different climates and almost certainly to different associates.
Hence we can see why each species appears to have been produced singly,
in space and in time. I need hardly remark that, according to this theory of
descent, there is no necessity of modification in a species, when it reaches a
new and isolated country. If it be able to survive and if slight variations
better adapted to the new conditions are not selected, it might retain (as far
as we can see) its old form for an indefinite time. As we see that some sub-
varieties produced under domestication are more variable than others, so in
nature, perhaps, some species and genera are more variable than others. The
same precise form, however, would probably be seldom preserved through
successive geological periods, or in widely and differently conditioned
countries{415}.
Finally, during the long periods of time and probably of oscillations of
level, necessary for the formation of a continent, we may conclude (as
above explained) that many forms would become extinct. These extinct
forms, and those surviving (whether or not modified and changed in
structure), will all be related in each continent in the same manner and
degree, as are the inhabitants of any two different sub-regions in that same
continent. I do not mean to say that, for instance, the present Marsupials of
Australia or Edentata and rodents of S. America have descended from any
one of the few fossils of the same orders which have been discovered in
these countries. It is possible that, in a very few instances, this may be the
case; but generally they must be considered as merely codescendants of
common stocks{416}. I believe in this, from the improbability, considering
the vast number of species, which (as explained in the last chapter) must by

our theory have existed, that the comparatively few fossils which have been
found should chance to be the immediate and linear progenitors of those
now existing. Recent as the yet discovered fossil mammifers of S. America
are, who will pretend to say that very many intermediate forms may not
have existed? Moreover, we shall see in the ensuing chapter that the very
existence of genera and species can be explained only by a few species of
each epoch leaving modified successors or new species to a future period;
and the more distant that future period, the fewer will be the linear heirs of
the former epoch. As by our theory, all mammifers must have descended
from the same parent stock, so is it necessary that each land now possessing
terrestrial mammifers shall at some time have been so far united to other
land as to permit the passage of mammifers{417}; and it accords with this
necessity, that in looking far back into the earth’s history we find, first
changes in the geographical distribution, and secondly a period when the
mammiferous forms most distinctive of two of the present main divisions of
the world were living together{418}.
I think then I am justified in asserting that most of the above
enumerated and often trivial points in the geographical distribution of past
and present organisms (which points must be viewed by the creationists as
so many ultimate facts) follow as a simple consequence of specific forms
being mutable and of their being adapted by natural selection to diverse
ends, conjoined with their powers of dispersal, and the geologico-
geographical changes now in slow progress and which undoubtedly have
taken place. This large class of facts being thus explained, far more than
counterbalances many separate difficulties and apparent objections in
convincing my mind of the truth of this theory of common descent.

Improbability of finding fossil forms intermediate between
existing species.
There is one observation of considerable importance that may be here
introduced, with regard to the improbability of the chief transitional forms
between any two species being found fossil. With respect to the finer shades
of transition, I have before remarked that no one has any cause to expect to
trace them in a fossil state, without he be bold enough to imagine that
geologists at a future epoch will be able to trace from fossil bones the
gradations between the Short-Horns, Herefordshire, and Alderney breeds of

cattle{419}. I have attempted to show that rising islands, in process of
formation, must be the best nurseries of new specific forms, and these
points are the least favourable for the embedment of fossils{420}: I appeal, as
evidence, to the state of the numerous scattered islands in the several great
oceans: how rarely do any sedimentary deposits occur on them; and when
present they are mere narrow fringes of no great antiquity, which the sea is
generally wearing away and destroying. The cause of this lies in isolated
islands being generally volcanic and rising points; and the effects of
subterranean elevation is to bring up the surrounding newly-deposited strata
within the destroying action of the coast-waves: the strata, deposited at
greater distances, and therefore in the depths of the ocean, will be almost
barren of organic remains. These remarks may be generalised:—periods of
subsidence will always be most favourable to an accumulation of great
thicknesses of strata, and consequently to their long preservation; for
without one formation be protected by successive strata, it will seldom be
preserved to a distant age, owing to the enormous amount of denudation,
which seems to be a general contingent of time{421}. I may refer, as evidence
of this remark, to the vast amount of subsidence evident in the great pile of
the European formations, from the Silurian epoch to the end of the
Secondary, and perhaps to even a later period. Periods of elevation on the
other hand cannot be favourable to the accumulation of strata and their
preservation to distant ages, from the circumstance just alluded to, viz. of
elevation tending to bring to the surface the circum-littoral strata (always
abounding most in fossils) and destroying them. The bottom of tracts of
deep water (little favourable, however, to life) must be excepted from this
unfavourable influence of elevation. In the quite open ocean, probably no
sediment{422} is accumulating, or at a rate so slow as not to preserve fossil
remains, which will always be subject to disintegration. Caverns, no doubt,
will be equally likely to preserve terrestrial fossils in periods of elevation
and of subsidence; but whether it be owing to the enormous amount of
denudation, which all land seems to have undergone, no cavern with fossil
bones has been found belonging to the Secondary period{423}.
Hence many more remains will be preserved to a distant age, in any
region of the world, during periods of its subsidence{424}, than of its
elevation.

But during the subsidence of a tract of land, its inhabitants (as before
shown) will from the decrease of space and of the diversity of its stations,
and from the land being fully preoccupied by species fitted to diversified
means of subsistence, be little liable to modification from selection,
although many may, or rather must, become extinct. With respect to its
circum-marine inhabitants, although during a change from a continent to a
great archipelago, the number of stations fitted for marine beings will be
increased, their means of diffusion (an important check to change of form)
will be greatly improved; for a continent stretching north and south, or a
quite open space of ocean, seems to be to them the only barrier. On the
other hand, during the elevation of a small archipelago and its conversion
into a continent, we have, whilst the number of stations are increasing, both
for aquatic and terrestrial productions, and whilst these stations are not fully
preoccupied by perfectly adapted species, the most favourable conditions
for the selection of new specific forms; but few of them in their early
transitional states will be preserved to a distant epoch. We must wait during
an enormous lapse of time, until long-continued subsidence shall have taken
the place in this quarter of the world of the elevatory process, for the best
conditions of the embedment and the preservation of its inhabitants.
Generally the great mass of the strata in every country, from having been
chiefly accumulated during subsidence, will be the tomb, not of transitional
forms, but of those either becoming extinct or remaining unmodified.
The state of our knowledge, and the slowness of the changes of level, do
not permit us to test the truth of these remarks, by observing whether there
are more transitional or “fine” (as naturalists would term them) species, on
a rising and enlarging tract of land, than on an area of subsidence. Nor do I
know whether there are more “fine” species on isolated volcanic islands in
process of formation, than on a continent; but I may remark, that at the
Galapagos Archipelago the number of forms, which according to some
naturalists are true species, and according to others are mere races, is
considerable: this particularly applies to the different species or races of the
same genera inhabiting the different islands of this archipelago.
Furthermore it may be added (as bearing on the great facts discussed in this
chapter) that when naturalists confine their attention to any one country,
they have comparatively little difficulty in determining what forms to call
species and what to call varieties; that is, those which can or cannot be

traced or shown to be probably descendants of some other form: but the
difficulty increases, as species are brought from many stations, countries
and islands. It was this increasing (but I believe in few cases insuperable)
difficulty which seems chiefly to have urged Lamarck to the conclusion that
species are mutable.

CHAPTER VII
on the nature of the affinities and classification
{425}
of organic beings

Gradual appearance and disappearance of groups.
It has been observed from the earliest times that organic beings fall into
groups{426}, and these groups into others of several values, such as species
into genera, and then into sub-families, into families, orders, &c. The same
fact holds with those beings which no longer exist. Groups of species seem
to follow the same laws in their appearance and extinction{427}, as do the
individuals of any one species: we have reason to believe that, first, a few
species appear, that their numbers increase; and that, when tending to
extinction, the numbers of the species decrease, till finally the group
becomes extinct, in the same way as a species becomes extinct, by the
individuals becoming rarer and rarer. Moreover, groups, like the individuals
of a species, appear to become extinct at different times in different
countries. The Palæotherium was extinct much sooner in Europe than in
India: the Trigonia{428} was extinct in early ages in Europe, but now lives in
the seas of Australia. As it happens that one species of a family will endure
for a much longer period than another species, so we find that some whole
groups, such as Mollusca, tend to retain their forms, or to remain persistent,
for longer periods than other groups, for instance than the Mammalia.
Groups therefore, in their appearance, extinction, and rate of change or
succession, seem to follow nearly the same laws with the individuals of a
species{429}.

What is the Natural System?
The proper arrangement of species into groups, according to the natural
system, is the object of all naturalists; but scarcely two naturalists will give
the same answer to the question, What is the natural system and how are we
to recognise it? The most important characters{430} it might be thought (as it
was by the earliest classifiers) ought to be drawn from those parts of the

structure which determine its habits and place in the economy of nature,
which we may call the final end of its existence. But nothing is further from
the truth than this; how much external resemblance there is between the
little otter (Chironectes) of Guiana and the common otter; or again between
the common swallow and the swift; and who can doubt that the means and
ends of their existence are closely similar, yet how grossly wrong would be
the classification, which put close to each other a Marsupial and Placental
animal, and two birds with widely different skeletons. Relations, such as in
the two latter cases, or as that between the whale and fishes, are
denominated “analogical{431},” or are sometimes described as “relations of
adaption.” They are infinitely numerous and often very singular; but are of
no use in the classification of the higher groups. How it comes, that certain
parts of the structure, by which the habits and functions of the species are
settled, are of no use in classification, whilst other parts, formed at the same
time, are of the greatest, it would be difficult to say, on the theory of
separate creations.
Some authors as Lamarck, Whewell &c., believe that the degree of
affinity on the natural system depends on the degrees of resemblance in
organs more or less physiologically important for the preservation of life.
This scale of importance in the organs is admitted to be of difficult
discovery. But quite independent of this, the proposition, as a general rule,
must be rejected as false; though it may be partially true. For it is
universally admitted that the same part or organ, which is of the highest
service in classification in one group, is of very little use in another group,
though in both groups, as far as we can see, the part or organ is of equal
physiological importance: moreover, characters quite unimportant
physiologically, such as whether the covering of the body consists of hair or
feathers, whether the nostrils communicated with the mouth{432} &c., &c.,
are of the highest generality in classification; even colour, which is so
inconstant in many species, will sometimes well characterise even a whole
group of species. Lastly, the fact, that no one character is of so much
importance in determining to what great group an organism belongs, as the
forms through which the embryo{433} passes from the germ upwards to
maturity, cannot be reconciled with the idea that natural classification
follows according to the degrees of resemblance in the parts of most
physiological importance. The affinity of the common rock-barnacle with

the Crustaceans can hardly be perceived in more than a single character in
its mature state, but whilst young, locomotive, and furnished with eyes, its
affinity cannot be mistaken{434}. The cause of the greater value of characters,
drawn from the early stages of life, can, as we shall in a succeeding chapter
see, be in a considerable degree explained, on the theory of descent,
although inexplicable on the views of the creationist.
Practically, naturalists seem to classify according to the resemblance of
those parts or organs which in related groups are most uniform, or vary
least{435}: thus the æstivation, or manner in which the petals etc. are folded
over each other, is found to afford an unvarying character in most families
of plants, and accordingly any difference in this respect would be sufficient
to cause the rejection of a species from many families; but in the Rubiaceæ
the æstivation is a varying character, and a botanist would not lay much
stress on it, in deciding whether or not to class a new species in this family.
But this rule is obviously so arbitrary a formula, that most naturalists seem
to be convinced that something ulterior is represented by the natural system;
they appear to think that we only discover by such similarities what the
arrangement of the system is, not that such similarities make the system. We
can only thus understand Linnæus’{436} well-known saying, that the
characters do not make the genus; but that the genus gives the characters:
for a classification, independent of characters, is here presupposed. Hence
many naturalists have said that the natural system reveals the plan of the
Creator: but without it be specified whether order in time or place, or what
else is meant by the plan of the Creator, such expressions appear to me to
leave the question exactly where it was.
Some naturalists consider that the geographical position{437} of a species
may enter into the consideration of the group into which it should be
placed; and most naturalists (either tacitly or openly) give value to the
different groups, not solely by their relative differences in structure, but by
the number of forms included in them. Thus a genus containing a few
species might be, and has often been, raised into a family on the discovery
of several other species. Many natural families are retained, although most
closely related to other families, from including a great number of closely
similar species. The more logical naturalist would perhaps, if he could,
reject these two contingents in classification. From these circumstances, and
especially from the undefined objects and criterions of the natural system,

the number of divisions, such as genera, sub-families, families, &c., &c.,
has been quite arbitrary{438}; without the clearest definition, how can it be
possible to decide whether two groups of species are of equal value, and of
what value? whether they should both be called genera or families; or
whether one should be a genus, and the other a family{439}?

On the kind of relation between distinct groups.
I have only one other remark on the affinities of organic beings; that is,
when two quite distinct groups approach each other, the approach is
generally generic{440} and not special; I can explain this most easily by an
example: of all Rodents the Bizcacha, by certain peculiarities in its
reproductive system, approaches nearest to the Marsupials; of all
Marsupials the Phascolomys, on the other hand, appears to approach in the
form of its teeth and intestines nearest to the Rodents; but there is no special
relation between these two genera{441}; the Bizcacha is no nearer related to
the Phascolomys than to any other Marsupial in the points in which it
approaches this division; nor again is the Phascolomys, in the points of
structure in which it approaches the Rodents, any nearer related to the
Bizcacha than to any other Rodent. Other examples might have been
chosen, but I have given (from Waterhouse) this example as it illustrates
another point, namely, the difficulty of determining what are analogical or
adaptive and what real affinities; it seems that the teeth of the Phascolomys
though appearing closely to resemble those of a Rodent are found to be
built on the Marsupial type; and it is thought that these teeth and
consequently the intestines may have been adapted to the peculiar life of
this animal and therefore may not show any real relation. The structure in
the Bizcacha that connects it with the Marsupials does not seem a
peculiarity related to its manner of life, and I imagine that no one would
doubt that this shows a real affinity, though not more with any one
Marsupial species than with another. The difficulty of determining what
relations are real and what analogical is far from surprising when no one
pretends to define the meaning of the term relation or the ulterior object of
all classification. We shall immediately see on the theory of descent how it
comes that there should be “real” and “analogical” affinities; and why the
former alone should be of value in classification—difficulties which it
would be I believe impossible to explain on the ordinary theory of separate
creations.

Classification of Races or Varieties.
Let us now for a few moments turn to the classification of the generally
acknowledged varieties and subdivisions of our domestic beings{442}; we
shall find them systematically arranged in groups of higher and higher
value. De Candolle has treated the varieties of the cabbage exactly as he
would have done a natural family with various divisions and subdivisions.
In dogs again we have one main division which may be called the family of
hounds; of these, there are several (we will call them) genera, such as
blood-hounds, fox-hounds, and harriers; and of each of these we have
different species, as the blood-hound of Cuba and that of England; and of
the latter again we have breeds truly producing their own kind, which may
be called races or varieties. Here we see a classification practically used
which typifies on a lesser scale that which holds good in nature. But
amongst true species in the natural system and amongst domestic races the
number of divisions or groups, instituted between those most alike and
those most unlike, seems to be quite arbitrary. The number of the forms in
both cases seems practically, whether or not it ought theoretically, to
influence the denomination of groups including them. In both, geographical
distribution has sometimes been used as an aid to classification{443};
amongst varieties, I may instance, the cattle of India or the sheep of Siberia,
which from possessing some characters in common permit a classification
of Indian and European cattle, or Siberian and European sheep. Amongst
domestic varieties we have even something very like the relations of
“analogy” or “adaptation{444}”; thus the common and Swedish turnip are
both artificial varieties which strikingly resemble each other, and they fill
nearly the same end in the economy of the farm-yard; but although the
swede so much more resembles a turnip than its presumed parent the field
cabbage, no one thinks of putting it out of the cabbages into the turnips.
Thus the greyhound and racehorse, having been selected and trained for
extreme fleetness for short distances, present an analogical resemblance of
the same kind, but less striking as that between the little otter (Marsupial) of
Guiana and the common otter; though these two otters are really less related
than «are» the horse and dog. We are even cautioned by authors treating on
varieties, to follow the natural in contradistinction of an artificial system
and not, for instance, to class two varieties of the pine-apple{445} near each
other, because their fruits accidentally resemble each other closely (though

the fruit may be called the final end of this plant in the economy of its
world, the hothouse), but to judge from the general resemblance of the
entire plants. Lastly, varieties often become extinct; sometimes from
unexplained causes, sometimes from accident, but more often from the
production of more useful varieties, and the less useful ones being
destroyed or bred out.
I think it cannot be doubted that the main cause of all the varieties
which have descended from the aboriginal dog or dogs, or from the
aboriginal wild cabbage, not being equally like or unlike—but on the
contrary, obviously falling into groups and sub-groups—must in chief part
be attributed to different degrees of true relationship; for instance, that the
different kinds of blood-hound have descended from one stock, whilst the
harriers have descended from another stock, and that both these have
descended from a different stock from that which has been the parent of the
several kinds of greyhound. We often hear of a florist having some choice
variety and breeding from it a whole group of sub-varieties more or less
characterised by the peculiarities of the parent. The case of the peach and
nectarine, each with their many varieties, might have been introduced. No
doubt the relationship of our different domestic breeds has been obscured in
an extreme degree by their crossing; and likewise from the slight difference
between many breeds it has probably often happened that a “sport” from
one breed has less closely resembled its parent breed than some other breed,
and has therefore been classed with the latter. Moreover the effects of a
similar climate{446} may in some cases have more than counterbalanced the
similarity, consequent on a common descent, though I should think the
similarity of the breeds of cattle of India or sheep of Siberia was far more
probably due to the community of their descent than to the effects of
climate on animals descended from different stocks.
Notwithstanding these great sources of difficulty, I apprehend every one
would admit, that if it were possible, a genealogical classification of our
domestic varieties would be the most satisfactory one; and as far as
varieties were concerned would be the natural system: in some cases it has
been followed. In attempting to follow out this object a person would have
to class a variety, whose parentage he did not know, by its external
characters; but he would have a distinct ulterior object in view, namely, its
descent in the same manner as a regular systematist seems also to have an

ulterior but undefined end in all his classifications. Like the regular
systematist he would not care whether his characters were drawn from more
or less important organs as long as he found in the tribe which he was
examining that the characters from such parts were persistent; thus amongst
cattle he does value a character drawn from the form of the horns more than
from the proportions of the limbs and whole body, for he finds that the
shape of the horns is to a considerable degree persistent amongst cattle{447},
whilst the bones of the limbs and body vary. No doubt as a frequent rule the
more important the organ, as being less related to external influences, the
less liable it is to variation; but he would expect that according to the object
for which the races had been selected, parts more or less important might
differ; so that characters drawn from parts generally most liable to vary, as
colour, might in some instances be highly serviceable—as is the case. He
would admit that general resemblances scarcely definable by language
might sometimes serve to allocate a species by its nearest relation. He
would be able to assign a clear reason why the close similarity of the fruit in
two varieties of pine-apple, and of the so-called root in the common and
Swedish turnips, and why the similar gracefulness of form in the greyhound
and racehorse, are characters of little value in classification; namely,
because they are the result, not of community of descent, but either of
selection for a common end, or of the effects of similar external conditions.

Classification of "races" and species similar.
Thus seeing that both the classifiers of species and of varieties{448} work
by the same means, make similar distinctions in the value of the characters,
and meet with similar difficulties, and that both seem to have in their
classification an ulterior object in view; I cannot avoid strongly suspecting
that the same cause, which has made amongst our domestic varieties groups
and sub-groups, has made similar groups (but of higher values) amongst
species; and that this cause is the greater or less propinquity of actual
descent. The simple fact of species, both those long since extinct and those
now living, being divisible into genera, families, orders &c.—divisions
analogous to those into which varieties are divisible—is otherwise an
inexplicable fact, and only not remarkable from its familiarity.

Origin of genera and families.

Let us suppose{449} for example that a species spreads and arrives at six
or more different regions, or being already diffused over one wide area, let
this area be divided into six distinct regions, exposed to different
conditions, and with stations slightly different, not fully occupied with other
species, so that six different races or species were formed by selection, each
best fitted to its new habits and station. I must remark that in every case, if a
species becomes modified in any one sub-region, it is probable that it will
become modified in some other of the sub-regions over which it is diffused,
for its organization is shown to be capable of being rendered plastic; its
diffusion proves that it is able to struggle with the other inhabitants of the
several sub-regions; and as the organic beings of every great region are in
some degree allied, and as even the physical conditions are often in some
respects alike, we might expect that a modification in structure, which gave
our species some advantage over antagonist species in one sub-region,
would be followed by other modifications in other of the sub-regions. The
races or new species supposed to be formed would be closely related to
each other; and would either form a new genus or sub-genus, or would rank
(probably forming a slightly different section) in the genus to which the
parent species belonged. In the course of ages, and during the contingent
physical changes, it is probable that some of the six new species would be
destroyed; but the same advantage, whatever it may have been (whether
mere tendency to vary, or some peculiarity of organization, power of mind,
or means of distribution), which in the parent-species and in its six selected
and changed species-offspring, caused them to prevail over other antagonist
species, would generally tend to preserve some or many of them for a long
period. If then, two or three of the six species were preserved, they in their
turn would, during continued changes, give rise to as many small groups of
species: if the parents of these small groups were closely similar, the new
species would form one great genus, barely perhaps divisible into two or
three sections: but if the parents were considerably unlike, their species-
offspring would, from inheriting most of the peculiarities of their parent-
stocks, form either two or more sub-genera or (if the course of selection
tended in different ways) genera. And lastly species descending from
different species of the newly formed genera would form new genera, and
such genera collectively would form a family.

The extermination of species follows from changes in the external
conditions, and from the increase or immigration of more favoured species:
and as those species which are undergoing modification in any one great
region (or indeed over the world) will very often be allied ones from (as just
explained) partaking of many characters, and therefore advantages in
common, so the species, whose place the new or more favoured ones are
seizing, from partaking of a common inferiority (whether in any particular
point of structure, or of general powers of mind, of means of distribution, of
capacity for variation, &c., &c.), will be apt to be allied. Consequently
species of the same genus will slowly, one after the other, tend to become
rarer and rarer in numbers, and finally extinct; and as each last species of
several allied genera fails, even the family will become extinct. There may
of course be occasional exceptions to the entire destruction of any genus or
family. From what has gone before, we have seen that the slow and
successive formation of several new species from the same stock will make
a new genus, and the slow and successive formation of several other new
species from another stock will make another genus; and if these two stocks
were allied, such genera will make a new family. Now, as far as our
knowledge serves, it is in this slow and gradual manner that groups of
species appear on, and disappear from, the face of the earth.
The manner in which, according to our theory, the arrangement of
species in groups is due to partial extinction, will perhaps be rendered
clearer in the following way. Let us suppose in any one great class, for
instance in the Mammalia, that every species and every variety, during each
successive age, had sent down one unaltered descendant (either fossil or
living) to the present time; we should then have had one enormous series,
including by small gradations every known mammiferous form; and
consequently the existence of groups{450}, or chasms in the series, which in
some parts are in greater width, and in some of less, is solely due to former
species, and whole groups of species, not having thus sent down
descendants to the present time.
With respect to the “analogical” or “adaptive” resemblances between
organic beings which are not really related{451}, I will only add, that
probably the isolation of different groups of species is an important element
in the production of such characters: thus we can easily see, in a large
increasing island, or even a continent like Australia, stocked with only

certain orders of the main classes, that the conditions would be highly
favourable for species from these orders to become adapted to play parts in
the economy of nature, which in other countries were performed by tribes
especially adapted to such parts. We can understand how it might happen
that an otter-like animal might have been formed in Australia by slow
selection from the more carnivorous Marsupial types; thus we can
understand that curious case in the southern hemisphere, where there are no
auks (but many petrels), of a petrel{452} having been modified into the
external general form so as to play the same office in nature with the auks
of the northern hemisphere; although the habits and form of the petrels and
auks are normally so wholly different. It follows, from our theory, that two
orders must have descended from one common stock at an immensely
remote epoch; and we can perceive when a species in either order, or in
both, shows some affinity to the other order, why the affinity is usually
generic and not particular—that is why the Bizcacha amongst Rodents, in
the points in which it is related to the Marsupial, is related to the whole
group{453}, and not particularly to the Phascolomys, which of all Marsupialia
is related most to the Rodents. For the Bizcacha is related to the present
Marsupialia, only from being related to their common parent-stock; and not
to any one species in particular. And generally, it may be observed in the
writings of most naturalists, that when an organism is described as
intermediate between two great groups, its relations are not to particular
species of either group, but to both groups, as wholes. A little reflection will
show how exceptions (as that of the Lepidosiren, a fish closely related to
particular reptiles) might occur, namely from a few descendants of those
species, which at a very early period branched out from a common parent-
stock and so formed the two orders or groups, having survived, in nearly
their original state, to the present time.
Finally, then, we see that all the leading facts in the affinities and
classification of organic beings can be explained on the theory of the natural
system being simply a genealogical one. The similarity of the principles in
classifying domestic varieties and true species, both those living and
extinct, is at once explained; the rules followed and difficulties met with
being the same. The existence of genera, families, orders, &c., and their
mutual relations, naturally ensues from extinction going on at all periods
amongst the diverging descendants of a common stock. These terms of

affinity, relations, families, adaptive characters, &c., which naturalists
cannot avoid using, though metaphorically, cease being so, and are full of
plain signification.

CHAPTER VIII
unity of type in the great classes; and
morphological structures

Unity of Type{454}.
Scarcely anything is more wonderful or has been oftener insisted on
than that the organic beings in each great class, though living in the most
distant climes and at periods immensely remote, though fitted to widely
different ends in the economy of nature, yet all in their internal structure
evince an obvious uniformity. What, for instance, is more wonderful than
that the hand to clasp, the foot or hoof to walk, the bat’s wing to fly, the
porpoise’s fin{455} to swim, should all be built on the same plan? and that the
bones in their position and number should be so similar that they can all be
classed and called by the same names. Occasionally some of the bones are
merely represented by an apparently useless, smooth style, or are soldered
closely to other bones, but the unity of type is not by this destroyed, and
hardly rendered less clear. We see in this fact some deep bond of union
between the organic beings of the same great classes—to illustrate which is
the object and foundation of the natural system. The perception of this
bond, I may add, is the evident cause that naturalists make an ill-defined
distinction between true and adaptive affinities.

Morphology.
There is another allied or rather almost identical class of facts admitted
by the least visionary naturalists and included under the name of
Morphology. These facts show that in an individual organic being, several
of its organs consist of some other organ metamorphosed{456}: thus the
sepals, petals, stamens, pistils, &c. of every plant can be shown to be
metamorphosed leaves; and thus not only can the number, position and
transitional states of these several organs, but likewise their monstrous
changes, be most lucidly explained. It is believed that the same laws hold
good with the gemmiferous vesicles of Zoophytes. In the same manner the

number and position of the extraordinarily complicated jaws and palpi of
Crustacea and of insects, and likewise their differences in the different
groups, all become simple, on the view of these parts, or rather legs and all
metamorphosed appendages, being metamorphosed legs. The skulls, again,
of the Vertebrata are composed of three metamorphosed vertebræ, and thus
we can see a meaning in the number and strange complication of the bony
case of the brain. In this latter instance, and in that of the jaws of the
Crustacea, it is only necessary to see a series taken from the different
groups of each class to admit the truth of these views. It is evident that
when in each species of a group its organs consist of some other part
metamorphosed, that there must also be a “unity of type” in such a group.
And in the cases as that above given in which the foot, hand, wing and
paddle are said to be constructed on a uniform type, if we could perceive in
such parts or organs traces of an apparent change from some other use or
function, we should strictly include such parts or organs in the department
of morphology: thus if we could trace in the limbs of the Vertebrata, as we
can in their ribs, traces of an apparent change from being processes of the
vertebræ, it would be said that in each species of the Vertebrata the limbs
were “metamorphosed spinal processes,” and that in all the species
throughout the class the limbs displayed a “unity of type{457}.”
These wonderful parts of the hoof, foot, hand, wing, paddle, both in
living and extinct animals, being all constructed on the same framework,
and again of the petals, stamina, germens, &c. being metamorphosed
leaves, can by the creationist be viewed only as ultimate facts and incapable
of explanation; whilst on our theory of descent these facts all necessary
follow: for by this theory all the beings of any one class, say of the
mammalia, are supposed to be descended from one parent-stock, and to
have been altered by such slight steps as man effects by the selection of
chance domestic variations. Now we can see according to this view that a
foot might be selected with longer and longer bones, and wider connecting
membranes, till it became a swimming organ, and so on till it became an
organ by which to flap along the surface or to glide over it, and lastly to fly
through the air: but in such changes there would be no tendency to alter the
framework of the internal inherited structure. Parts might become lost (as
the tail in dogs, or horns in cattle, or the pistils in plants), others might
become united together (as in the feet of the Lincolnshire breed of pigs{458},

and in the stamens of many garden flowers); parts of a similar nature might
become increased in number (as the vertebræ in the tails of pigs, &c., &c.
and the fingers and toes in six-fingered races of men and in the Dorking
fowls), but analogous differences are observed in nature and are not
considered by naturalists to destroy the uniformity of the types. We can,
however, conceive such changes to be carried to such length that the unity
of type might be obscured and finally be undistinguishable, and the paddle
of the Plesiosaurus has been advanced as an instance in which the
uniformity of type can hardly be recognised{459}. If after long and gradual
changes in the structure of the co-descendants from any parent stock,
evidence (either from monstrosities or from a graduated series) could be
still detected of the function, which certain parts or organs played in the
parent stock, these parts or organs might be strictly determined by their
former function with the term “metamorphosed” appended. Naturalists have
used this term in the same metaphorical manner as they have been obliged
to use the terms of affinity and relation; and when they affirm, for instance,
that the jaws of a crab are metamorphosed legs, so that one crab has more
legs and fewer jaws than another, they are far from meaning that the jaws,
either during the life of the individual crab or of its progenitors, were really
legs. By our theory this term assumes its literal meaning{460}; and this
wonderful fact of the complex jaws of an animal retaining numerous
characters, which they would probably have retained if they had really been
metamorphosed during many successive generations from true legs, is
simply explained.

Embryology.
The unity of type in the great classes is shown in another and very
striking manner, namely, in the stages through which the embryo passes in
coming to maturity{461}. Thus, for instance, at one period of the embryo, the
wings of the bat, the hand, hoof or foot of the quadruped, and the fin of the
porpoise do not differ, but consist of a simple undivided bone. At a still
earlier period the embryo of the fish, bird, reptile and mammal all strikingly
resemble each other. Let it not be supposed this resemblance is only
external; for on dissection, the arteries are found to branch out and run in a
peculiar course, wholly unlike that in the full-grown mammal and bird, but
much less unlike that in the full-grown fish, for they run as if to ærate blood
by branchiæ{462} on the neck, of which even the slit-like orifices can be

discerned. How wonderful it is that this structure should be present in the
embryos of animals about to be developed into such different forms, and of
which two great classes respire only in the air. Moreover, as the embryo of
the mammal is matured in the parent’s body, and that of the bird in an egg
in the air, and that of the fish in an egg in the water, we cannot believe that
this course of the arteries is related to any external conditions. In all shell-
fish (Gasteropods) the embryo passes through a state analogous to that of
the Pteropodous Mollusca: amongst insects again, even the most different
ones, as the moth, fly and beetle, the crawling larvæ are all closely
analogous: amongst the Radiata, the jelly-fish in its embryonic state
resembles a polype, and in a still earlier state an infusorial animalcule—as
does likewise the embryo of the polype. From the part of the embryo of a
mammal, at one period, resembling a fish more than its parent form; from
the larvæ of all orders of insects more resembling the simpler articulate
animals than their parent insects{463}; and from such other cases as the
embryo of the jelly-fish resembling a polype much nearer than the perfect
jelly-fish; it has often been asserted that the higher animal in each class
passes through the state of a lower animal; for instance, that the mammal
amongst the vertebrata passes through the state of a fish{464}: but Müller
denies this, and affirms that the young mammal is at no time a fish, as does
Owen assert that the embryonic jelly-fish is at no time a polype, but that
mammal and fish, jelly-fish and polype pass through the same state; the
mammal and jelly-fish being only further developed or changed.
As the embryo, in most cases, possesses a less complicated structure
than that into which it is to be developed, it might have been thought that
the resemblance of the embryo to less complicated forms in the same great
class, was in some manner a necessary preparation for its higher
development; but in fact the embryo, during its growth, may become less,
as well as more, complicated{465}. Thus certain female Epizoic Crustaceans
in their mature state have neither eyes nor any organs of locomotion; they
consist of a mere sack, with a simple apparatus for digestion and
procreation; and when once attached to the body of the fish, on which they
prey, they never move again during their whole lives: in their embryonic
condition, on the other hand, they are furnished with eyes, and with well
articulated limbs, actively swim about and seek their proper object to
become attached to. The larvæ, also, of some moths are as complicated and

are more active than the wingless and limbless females, which never leave
their pupa-case, never feed and never see the daylight.

Attempt to explain the facts of embryology.
I think considerable light can be thrown by the theory of descent on
these wonderful embryological facts which are common in a greater or less
degree to the whole animal kingdom, and in some manner to the vegetable
kingdom: on the fact, for instance, of the arteries in the embryonic mammal,
bird, reptile and fish, running and branching in the same courses and nearly
in the same manner with the arteries in the full-grown fish; on the fact I
may add of the high importance to systematic naturalists{466} of the
characters and resemblances in the embryonic state, in ascertaining the true
position in the natural system of mature organic beings. The following are
the considerations which throw light on these curious points.
In the economy, we will say of a feline animal{467}, the feline structure of
the embryo or of the sucking kitten is of quite secondary importance to it;
hence, if a feline animal varied (assuming for the time the possibility of
this) and if some place in the economy of nature favoured the selection of a
longer-limbed variety, it would be quite unimportant to the production by
natural selection of a long-limbed breed, whether the limbs of the embryo
and kitten were elongated if they became so as soon as the animal had to
provide food for itself. And if it were found after continued selection and
the production of several new breeds from one parent-stock, that the
successive variations had supervened, not very early in the youth or
embryonic life of each breed (and we have just seen that it is quite
unimportant whether it does so or not), then it obviously follows that the
young or embryos of the several breeds will continue resembling each other
more closely than their adult parents{468}. And again, if two of these breeds
became each the parent-stock of several other breeds, forming two genera,
the young and embryos of these would still retain a greater resemblance to
the one original stock than when in an adult state. Therefore if it could be
shown that the period of the slight successive variations does not always
supervene at a very early period of life, the greater resemblance or closer
unity in type of animals in the young than in the full-grown state would be
explained. Before practically{469} endeavouring to discover in our domestic
races whether the structure or form of the young has or has not changed in

an exactly corresponding degree with the changes of full-grown animals, it
will be well to show that it is at least quite possible for the primary germinal
vesicle to be impressed with a tendency to produce some change on the
growing tissues which will not be fully effected till the animal is advanced
in life.
From the following peculiarities of structure being inheritable and
appearing only when the animal is full-grown—namely, general size,
tallness (not consequent on the tallness of the infant), fatness either over the
whole body, or local; change of colour in hair and its loss; deposition of
bony matter on the legs of horses; blindness and deafness, that is changes of
structure in the eye and ear; gout and consequent deposition of chalk-
stones; and many other diseases{470}, as of the heart and brain, &c., &c.;
from all such tendencies being I repeat inheritable, we clearly see that the
germinal vesicle is impressed with some power which is wonderfully
preserved during the production of infinitely numerous cells in the ever
changing tissues, till the part ultimately to be affected is formed and the
time of life arrived at. We see this clearly when we select cattle with any
peculiarity of their horns, or poultry with any peculiarity of their second
plumage, for such peculiarities cannot of course reappear till the animal is
mature. Hence, it is certainly possible that the germinal vesicle may be
impressed with a tendency to produce a long-limbed animal, the full
proportional length of whose limbs shall appear only when the animal is
mature{471}.
In several of the cases just enumerated we know that the first cause of
the peculiarity, when not inherited, lies in the conditions to which the
animal is exposed during mature life, thus to a certain extent general size
and fatness, lameness in horses and in a lesser degree blindness, gout and
some other diseases are certainly in some degree caused and accelerated by
the habits of life, and these peculiarities when transmitted to the offspring
of the affected person reappear at a nearly corresponding time of life. In
medical works it is asserted generally that at whatever period an hereditary
disease appears in the parent, it tends to reappear in the offspring at the
same period. Again, we find that early maturity, the season of reproduction
and longevity are transmitted to corresponding periods of life. Dr Holland
has insisted much on children of the same family exhibiting certain diseases
in similar and peculiar manners; my father has known three brothers{472} die

in very old age in a singular comatose state; now to make these latter cases
strictly bear, the children of such families ought similarly to suffer at
corresponding times of life; this is probably not the case, but such facts
show that a tendency in a disease to appear at particular stages of life can be
transmitted through the germinal vesicle to different individuals of the same
family. It is then certainly possible that diseases affecting widely different
periods of life can be transmitted. So little attention is paid to very young
domestic animals that I do not know whether any case is on record of
selected peculiarities in young animals, for instance, in the first plumage of
birds, being transmitted to their young. If, however, we turn to silk-
worms{473}, we find that the caterpillars and coccoons (which must
correspond to a very early period of the embryonic life of mammalia) vary,
and that these varieties reappear in the offspring caterpillars and coccoons.
I think these facts are sufficient to render it probable that at whatever
period of life any peculiarity (capable of being inherited) appears, whether
caused by the action of external influences during mature life, or from an
affection of the primary germinal vesicle, it tends to reappear in the
offspring at the corresponding period of life{474}. Hence (I may add)
whatever effect training, that is the full employment or action of every
newly selected slight variation, has in fully developing and increasing such
variation, would only show itself in mature age, corresponding to the period
of training; in the second chapter I showed that there was in this respect a
marked difference in natural and artificial selection, man not regularly
exercising or adapting his varieties to new ends, whereas selection by
nature presupposes such exercise and adaptation in each selected and
changed part. The foregoing facts show and presuppose that slight
variations occur at various periods of life after birth; the facts of
monstrosity, on the other hand, show that many changes take place before
birth, for instance, all such cases as extra fingers, hare-lip and all sudden
and great alterations in structure; and these when inherited reappear during
the embryonic period in the offspring. I will only add that at a period even
anterior to embryonic life, namely, during the egg state, varieties appear in
size and colour (as with the Hertfordshire duck with blackish eggs{475})
which reappear in the egg; in plants also the capsule and membranes of the
seed are very variable and inheritable.

If then the two following propositions are admitted (and I think the first
can hardly be doubted), viz. that variation of structure takes place at all
times of life, though no doubt far less in amount and seldomer in quite
mature life{476} (and then generally taking the form of disease); and
secondly, that these variations tend to reappear at a corresponding period of
life, which seems at least probable, then we might a priori have expected
that in any selected breed the young animal would not partake in a
corresponding degree the peculiarities characterising the full-grown parent;
though it would in a lesser degree. For during the thousand or ten thousand
selections of slight increments in the length of the limbs of individuals
necessary to produce a long-limbed breed, we might expect that such
increments would take place in different individuals (as we do not certainly
know at what period they do take place), some earlier and some later in the
embryonic state, and some during early youth; and these increments would
reappear in their offspring only at corresponding periods. Hence, the entire
length of limb in the new long-limbed breed would only be acquired at the
latest period of life, when that one which was latest of the thousand primary
increments of length supervened. Consequently, the fœtus of the new breed
during the earlier part of its existence would remain much less changed in
the proportions of its limbs; and the earlier the period the less would the
change be.
Whatever may be thought of the facts on which this reasoning is
grounded, it shows how the embryos and young of different species might
come to remain less changed than their mature parents; and practically we
find that the young of our domestic animals, though differing, differ less
than their full-grown parents. Thus if we look at the young puppies{477} of
the greyhound and bulldog—(the two most obviously modified of the
breeds of dog)—we find their puppies at the age of six days with legs and
noses (the latter measured from the eyes to the tip) of the same length;
though in the proportional thicknesses and general appearance of these parts
there is a great difference. So it is with cattle, though the young calves of
different breeds are easily recognisable, yet they do not differ so much in
their proportions as the full-grown animals. We see this clearly in the fact
that it shows the highest skill to select the best forms early in life, either in
horses, cattle or poultry; no one would attempt it only a few hours after
birth; and it requires great discrimination to judge with accuracy even

during their full youth, and the best judges are sometimes deceived. This
shows that the ultimate proportions of the body are not acquired till near
mature age. If I had collected sufficient facts to firmly establish the
proposition that in artificially selected breeds the embryonic and young
animals are not changed in a corresponding degree with their mature
parents, I might have omitted all the foregoing reasoning and the attempts
to explain how this happens; for we might safely have transferred the
proposition to the breeds or species naturally selected; and the ultimate
effect would necessarily have been that in a number of races or species
descended from a common stock and forming several genera and families
the embryos would have resembled each other more closely than full-grown
animals. Whatever may have been the form or habits of the parent-stock of
the Vertebrata, in whatever course the arteries ran and branched, the
selection of variations, supervening after the first formation of the arteries
in the embryo, would not tend from variations supervening at corresponding
periods to alter their course at that period: hence, the similar course of the
arteries in the mammal, bird, reptile and fish, must be looked at as a most
ancient record of the embryonic structure of the common parent-stock of
these four great classes.
A long course of selection might cause a form to become more simple,
as well as more complicated; thus the adaptation of a crustaceous{478} animal
to live attached during its whole life to the body of a fish, might permit with
advantage great simplification of structure, and on this view the singular
fact of an embryo being more complex than its parent is at once explained.

On the graduated complexity in each great class.
I may take this opportunity of remarking that naturalists have observed
that in most of the great classes a series exists from very complicated to
very simple beings; thus in Fish, what a range there is between the sand-eel
and shark,—in the Articulata, between the common crab and the
Daphnia{479},—between the Aphis and butterfly, and between a mite and a
spider{480}. Now the observation just made, namely, that selection might
tend to simplify, as well as to complicate, explains this; for we can see that
during the endless geologico-geographical changes, and consequent
isolation of species, a station occupied in other districts by less complicated
animals might be left unfilled, and be occupied by a degraded form of a

higher or more complicated class; and it would by no means follow that,
when the two regions became united, the degraded organism would give
way to the aboriginally lower organism. According to our theory, there is
obviously no power tending constantly to exalt species, except the mutual
struggle between the different individuals and classes; but from the strong
and general hereditary tendency we might expect to find some tendency to
progressive complication in the successive production of new organic
forms.

Modification by selection of the forms of immature animals.
I have above remarked that the feline{481} form is quite of secondary
importance to the embryo and to the kitten. Of course, during any great and
prolonged change of structure in the mature animal, it might, and often
would be, indispensable that the form of the embryo should be changed;
and this could be effected, owing to the hereditary tendency at
corresponding ages, by selection, equally well as in mature age: thus if the
embryo tended to become, or to remain, either over its whole body or in
certain parts, too bulky, the female parent would die or suffer more during
parturition; and as in the case of the calves with large hinder quarters{482},
the peculiarity must be either eliminated or the species become extinct.
Where an embryonic form has to seek its own food, its structure and
adaptation is just as important to the species as that of the full-grown
animal; and as we have seen that a peculiarity appearing in a caterpillar (or
in a child, as shown by the hereditariness of peculiarities in the milk-teeth)
reappears in its offspring, so we can at once see that our common principle
of the selection of slight accidental variations would modify and adapt a
caterpillar to a new or changing condition, precisely as in the full-grown
butterfly. Hence probably it is that caterpillars of different species of the
Lepidoptera differ more than those embryos, at a corresponding early
period of life, do which remain inactive in the womb of their parents. The
parent during successive ages continuing to be adapted by selection for
some one object, and the larva for quite another one, we need not wonder at
the difference becoming wonderfully great between them; even as great as
that between the fixed rock-barnacle and its free, crab-like offspring, which
is furnished with eyes and well-articulated, locomotive limbs{483}.

Importance of embryology in classification.

We are now prepared to perceive why the study of embryonic forms is
of such acknowledged importance in classification{484}. For we have seen
that a variation, supervening at any time, may aid in the modification and
adaptation of the full-grown being; but for the modification of the embryo,
only the variations which supervene at a very early period can be seized on
and perpetuated by selection: hence there will be less power and less
tendency (for the structure of the embryo is mostly unimportant) to modify
the young: and hence we might expect to find at this period similarities
preserved between different groups of species which had been obscured and
quite lost in the full-grown animals. I conceive on the view of separate
creations it would be impossible to offer any explanation of the affinities of
organic beings thus being plainest and of the greatest importance at that
period of life when their structure is not adapted to the final part they have
to play in the economy of nature.

Order in time in which the great classes have first appeared.
It follows strictly from the above reasoning only that the embryos of
(for instance) existing vertebrata resemble more closely the embryo of the
parent-stock of this great class than do full-grown existing vertebrata
resemble their full-grown parent-stock. But it may be argued with much
probability that in the earliest and simplest condition of things the parent
and embryo must have resembled each other, and that the passage of any
animal through embryonic states in its growth is entirely due to subsequent
variations affecting only the more mature periods of life. If so, the embryos
of the existing vertebrata will shadow forth the full-grown structure of some
of those forms of this great class which existed at the earlier periods of the
earth's history{485}: and accordingly, animals with a fish-like structure ought
to have preceded birds and mammals; and of fish, that higher organized
division with the vertebræ extending into one division of the tail ought to
have preceded the equal-tailed, because the embryos of the latter have an
unequal tail; and of Crustacea, entomostraca ought to have preceded the
ordinary crabs and barnacles—polypes ought to have preceded jelly-fish,
and infusorial animalcules to have existed before both. This order of
precedence in time in some of these cases is believed to hold good; but I
think our evidence is so exceedingly incomplete regarding the number and
kinds of organisms which have existed during all, especially the earlier,

periods of the earth’s history, that I should put no stress on this accordance,
even if it held truer than it probably does in our present state of knowledge.

CHAPTER IX
abortive or rudimentary organs

The abortive organs of naturalists.
Parts of structure are said to be “abortive,” or when in a still lower state
of development “rudimentary{486},” when the same reasoning power, which
convinces us that in some cases similar parts are beautifully adapted to
certain ends, declares that in others they are absolutely useless. Thus the
rhinoceros, the whale{487}, etc., have, when young, small but properly
formed teeth, which never protrude from the jaws; certain bones, and even
the entire extremities are represented by mere little cylinders or points of
bone, often soldered to other bones: many beetles have exceedingly minute
but regularly formed wings lying under their wing-cases{488}, which latter
are united never to be opened: many plants have, instead of stamens, mere
filaments or little knobs; petals are reduced to scales, and whole flowers to
buds, which (as in the feather hyacinth) never expand. Similar instances are
almost innumerable, and are justly considered wonderful: probably not one
organic being exists in which some part does not bear the stamp of inutility;
for what can be clearer{489}, as far as our reasoning powers can reach, than
that teeth are for eating, extremities for locomotion, wings for flight,
stamens and the entire flower for reproduction; yet for these clear ends the
parts in question are manifestly unfit. Abortive organs are often said to be
mere representatives (a metaphorical expression) of similar parts in other
organic beings; but in some cases they are more than representatives, for
they seem to be the actual organ not fully grown or developed; thus the
existence of mammæ in the male vertebrata is one of the oftenest adduced
cases of abortion; but we know that these organs in man (and in the bull)
have performed their proper function and secreted milk: the cow has
normally four mammæ and two abortive ones, but these latter in some
instances are largely developed and even (??) give milk{490}. Again in
flowers, the representatives of stamens and pistils can be traced to be really
these parts not developed; Kölreuter has shown by crossing a diæcious plant
(a Cucubalus) having a rudimentary pistil{491} with another species having

this organ perfect, that in the hybrid offspring the rudimentary part is more
developed, though still remaining abortive; now this shows how intimately
related in nature the mere rudiment and the fully developed pistil must be.
Abortive organs, which must be considered as useless as far as their
ordinary and normal purpose is concerned, are sometimes adapted to other
ends{492}: thus the marsupial bones, which properly serve to support the
young in the mother’s pouch, are present in the male and serve as the
fulcrum for muscles connected only with male functions: in the male of the
marigold flower the pistil is abortive for its proper end of being
impregnated, but serves to sweep the pollen out of the anthers{493} ready to
be borne by insects to the perfect pistils in the other florets. It is likely in
many cases, yet unknown to us, that abortive organs perform some useful
function; but in other cases, for instance in that of teeth embedded in the
solid jaw-bone, or of mere knobs, the rudiments of stamens and pistils, the
boldest imagination will hardly venture to ascribe to them any function.
Abortive parts, even when wholly useless to the individual species, are of
great signification in the system of nature; for they are often found to be of
very high importance in a natural classification{494}; thus the presence and
position of entire abortive flowers, in the grasses, cannot be overlooked in
attempting to arrange them according to their true affinities. This
corroborates a statement in a previous chapter, viz. that the physiological
importance of a part is no index of its importance in classification. Finally,
abortive organs often are only developed, proportionally with other parts, in
the embryonic or young state of each species{495}; this again, especially
considering the classificatory importance of abortive organs, is evidently
part of the law (stated in the last chapter) that the higher affinities of
organisms are often best seen in the stages towards maturity, through which
the embryo passes. On the ordinary view of individual creations, I think that
scarcely any class of facts in natural history are more wonderful or less
capable of receiving explanation.

The abortive organs of physiologists.
Physiologists and medical men apply the term “abortive” in a somewhat
different sense from naturalists; and their application is probably the
primary one; namely, to parts, which from accident or disease before birth
are not developed or do not grow{496}: thus, when a young animal is born

with a little stump in the place of a finger or of the whole extremity, or with
a little button instead of a head, or with a mere bead of bony matter instead
of a tooth, or with a stump instead of a tail, these parts are said to be
aborted. Naturalists on the other hand, as we have seen, apply this term to
parts not stunted during the growth of the embryo, but which are as
regularly produced in successive generations as any other most essential
parts of the structure of the individual: naturalists, therefore, use this term in
a metaphorical sense. These two classes of facts, however, blend into each
other{497}; by parts accidentally aborted, during the embryonic life of one
individual, becoming hereditary in the succeeding generations: thus a cat or
dog, born with a stump instead of a tail, tends to transmit stumps to their
offspring; and so it is with stumps representing the extremities; and so again
with flowers, with defective and rudimentary parts, which are annually
produced in new flower-buds and even in successive seedlings. The strong
hereditary tendency to reproduce every either congenital or slowly acquired
structure, whether useful or injurious to the individual, has been shown in
the first part; so that we need feel no surprise at these truly abortive parts
becoming hereditary. A curious instance of the force of hereditariness is
sometimes seen in two little loose hanging horns, quite useless as far as the
function of a horn is concerned, which are produced in hornless races of our
domestic cattle{498}. Now I believe no real distinction can be drawn between
a stump representing a tail or a horn or the extremities; or a short shrivelled
stamen without any pollen; or a dimple in a petal representing a nectary,
when such rudiments are regularly reproduced in a race or family, and the
true abortive organs of naturalists. And if we had reason to believe (which I
think we have not) that all abortive organs had been at some period
suddenly produced during the embryonic life of an individual, and
afterwards become inherited, we should at once have a simple explanation
of the origin of abortive and rudimentary organs{499}. In the same manner as
during changes of pronunciation certain letters in a word may become
useless{500} in pronouncing it, but yet may aid us in searching for its
derivation, so we can see that rudimentary organs, no longer useful to the
individual, may be of high importance in ascertaining its descent, that is, its
true classification in the natural system.

Abortion from gradual disuse.

There seems to be some probability that continued disuse of any part or
organ, and the selection of individuals with such parts slightly less
developed, would in the course of ages produce in organic beings under
domesticity races with such parts abortive. We have every reason to believe
that every part and organ in an individual becomes fully developed only
with exercise of its functions; that it becomes developed in a somewhat
lesser degree with less exercise; and if forcibly precluded from all action,
such part will often become atrophied. Every peculiarity, let it be
remembered, tends, especially where both parents have it, to be inherited.
The less power of flight in the common duck compared with the wild, must
be partly attributed to disuse{501} during successive generations, and as the
wing is properly adapted to flight, we must consider our domestic duck in
the first stage towards the state of the Apteryx, in which the wings are so
curiously abortive. Some naturalists have attributed (and possibly with
truth) the falling ears so characteristic of most domestic dogs, some rabbits,
oxen, cats, goats, horses, &c., &c., as the effects of the lesser use of the
muscles of these flexible parts during successive generations of inactive
life; and muscles, which cannot perform their functions, must be considered
verging towards abortion. In flowers, again, we see the gradual abortion
during successive seedlings (though this is more properly a conversion) of
stamens into imperfect petals, and finally into perfect petals. When the eye
is blinded in early life the optic nerve sometimes becomes atrophied; may
we not believe that where this organ, as is the case with the subterranean
mole-like Tuco-tuco «Ctenomys»{502}, is frequently impaired and lost, that in
the course of generations the whole organ might become abortive, as it
normally is in some burrowing quadrupeds having nearly similar habits
with the Tuco-tuco?
In as far then as it is admitted as probable that the effects of disuse
(together with occasional true and sudden abortions during the embryonic
period) would cause a part to be less developed, and finally to become
abortive and useless; then during the infinitely numerous changes of habits
in the many descendants from a common stock, we might fairly have
expected that cases of organs becom«ing» abortive would have been
numerous. The preservation of the stump of the tail, as usually happens
when an animal is born tailless, we can only explain by the strength of the
hereditary principle and by the period in embryo when affected{503}: but on

the theory of disuse gradually obliterating a part, we can see, according to
the principles explained in the last chapter (viz. of hereditariness at
corresponding periods of life{504}, together with the use and disuse of the
part in question not being brought into play in early or embryonic life), that
organs or parts would tend not to be utterly obliterated, but to be reduced to
that state in which they existed in early embryonic life. Owen often speaks
of a part in a full-grown animal being in an “embryonic condition.”
Moreover we can thus see why abortive organs are most developed at an
early period of life. Again, by gradual selection, we can see how an organ
rendered abortive in its primary use might be converted to other purposes; a
duck’s wing might come to serve for a fin, as does that of the penguin; an
abortive bone might come to serve, by the slow increment and change of
place in the muscular fibres, as a fulcrum for a new series of muscles; the
pistil{505} of the marigold might become abortive as a reproductive part, but
be continued in its function of sweeping the pollen out of the anthers; for if
in this latter respect the abortion had not been checked by selection, the
species must have become extinct from the pollen remaining enclosed in the
capsules of the anthers.
Finally then I must repeat that these wonderful facts of organs formed
with traces of exquisite care, but now either absolutely useless or adapted to
ends wholly different from their ordinary end, being present and forming
part of the structure of almost every inhabitant of this world, both in long-
past and present times—being best developed and often only discoverable
at a very early embryonic period, and being full of signification in arranging
the long series of organic beings in a natural system—these wonderful facts
not only receive a simple explanation on the theory of long-continued
selection of many species from a few common parent-stocks, but
necessarily follow from this theory. If this theory be rejected, these facts
remain quite inexplicable; without indeed we rank as an explanation such
loose metaphors as that of De Candolle’s{506}, in which the kingdom of
nature is compared to a well-covered table, and the abortive organs are
considered as put in for the sake of symmetry!

CHAPTER X
recapitulation and conclusion

Recapitulation.
I will now recapitulate the course of this work, more fully with respect
to the former parts, and briefly «as to» the latter. In the first chapter we have
seen that most, if not all, organic beings, when taken by man out of their
natural condition, and bred during several generations, vary; that is
variation is partly due to the direct effect of the new external influences, and
partly to the indirect effect on the reproductive system rendering the
organization of the offspring in some degree plastic. Of the variations thus
produced, man when uncivilised naturally preserves the life, and therefore
unintentionally breeds from those individuals most useful to him in his
different states: when even semi-civilised, he intentionally separates and
breeds from such individuals. Every part of the structure seems occasionally
to vary in a very slight degree, and the extent to which all kinds of
peculiarities in mind and body, when congenital and when slowly acquired
either from external influences, from exercise, or from disuse «are
inherited», is truly wonderful. When several breeds are once formed, then
crossing is the most fertile source of new breeds{507}. Variation must be
ruled, of course, by the health of the new race, by the tendency to return to
the ancestral forms, and by unknown laws determining the proportional
increase and symmetry of the body. The amount of variation, which has
been effected under domestication, is quite unknown in the majority of
domestic beings.
In the second chapter it was shown that wild organisms undoubtedly
vary in some slight degree: and that the kind of variation, though much less
in degree, is similar to that of domestic organisms. It is highly probable that
every organic being, if subjected during several generations to new and
varying conditions, would vary. It is certain that organisms, living in an
isolated country which is undergoing geological changes, must in the
course of time be so subjected to new conditions; moreover an organism,

when by chance transported into a new station, for instance into an island,
will often be exposed to new conditions, and be surrounded by a new series
of organic beings. If there were no power at work selecting every slight
variation, which opened new sources of subsistence to a being thus situated,
the effects of crossing, the chance of death and the constant tendency to
reversion to the old parent-form, would prevent the production of new
races. If there were any selective agency at work, it seems impossible to
assign any limit{508} to the complexity and beauty of the adaptive structures,
which might thus be produced: for certainly the limit of possible variation
of organic beings, either in a wild or domestic state, is not known.
It was then shown, from the geometrically increasing tendency of each
species to multiply (as evidenced from what we know of mankind and of
other animals when favoured by circumstances), and from the means of
subsistence of each species on an average remaining constant, that during
some part of the life of each, or during every few generations, there must be
a severe struggle for existence; and that less than a grain{509} in the balance
will determine which individuals shall live and which perish. In a country,
therefore, undergoing changes, and cut off from the free immigration of
species better adapted to the new station and conditions, it cannot be
doubted that there is a most powerful means of selection, tending to
preserve even the slightest variation, which aided the subsistence or defence
of those organic beings, during any part of their whole existence, whose
organization had been rendered plastic. Moreover, in animals in which the
sexes are distinct, there is a sexual struggle, by which the most vigorous,
and consequently the best adapted, will oftener procreate their kind.
A new race thus formed by natural selection would be undistinguishable
from a species. For comparing, on the one hand, the several species of a
genus, and on the other hand several domestic races from a common stock,
we cannot discriminate them by the amount of external difference, but only,
first, by domestic races not remaining so constant or being so “true” as
species are; and secondly by races always producing fertile offspring when
crossed. And it was then shown that a race naturally selected—from the
variation being slower—from the selection steadily leading towards the
same ends{510}, and from every new slight change in structure being adapted
(as is implied by its selection) to the new conditions and being fully
exercised, and lastly from the freedom from occasional crosses with other

species, would almost necessarily be “truer” than a race selected by
ignorant or capricious and short-lived man. With respect to the sterility of
species when crossed, it was shown not to be a universal character, and
when present to vary in degree: sterility also was shown probably to depend
less on external than on constitutional differences. And it was shown that
when individual animals and plants are placed under new conditions, they
become, without losing their healths, as sterile, in the same manner and to
the same degree, as hybrids; and it is therefore conceivable that the cross-
bred offspring between two species, having different constitutions, might
have its constitution affected in the same peculiar manner as when an
individual animal or plant is placed under new conditions. Man in selecting
domestic races has little wish and still less power to adapt the whole frame
to new conditions; in nature, however, where each species survives by a
struggle against other species and external nature, the result must be very
different.
Races descending from the same stock were then compared with species
of the same genus, and they were found to present some striking analogies.
The offspring also of races when crossed, that is mongrels, were compared
with the cross-bred offspring of species, that is hybrids, and they were
found to resemble each other in all their characters, with the one exception
of sterility, and even this, when present, often becomes after some
generations variable in degree. The chapter was summed up, and it was
shown that no ascertained limit to the amount of variation is known; or
could be predicted with due time and changes of condition granted. It was
then admitted that although the production of new races, undistinguishable
from true species, is probable, we must look to the relations in the past and
present geographical distribution of the infinitely numerous beings, by
which we are surrounded—to their affinities and to their structure—for any
direct evidence.
In the third chapter the inheritable variations in the mental phenomena
of domestic and of wild organic beings were considered. It was shown that
we are not concerned in this work with the first origin of the leading mental
qualities; but that tastes, passions, dispositions, consensual movements, and
habits all became, either congenitally or during mature life, modified and
were inherited. Several of these modified habits were found to correspond
in every essential character with true instincts, and they were found to

follow the same laws. Instincts and dispositions &c. are fully as important
to the preservation and increase of a species as its corporeal structure; and
therefore the natural means of selection would act on and modify them
equally with corporeal structures. This being granted, as well as the
proposition that mental phenomena are variable, and that the modifications
are inheritable, the possibility of the several most complicated instincts
being slowly acquired was considered, and it was shown from the very
imperfect series in the instincts of the animals now existing, that we are not
justified in prima facie rejecting a theory of the common descent of allied
organisms from the difficulty of imagining the transitional stages in the
various now most complicated and wonderful instincts. We were thus led on
to consider the same question with respect both to highly complicated
organs, and to the aggregate of several such organs, that is individual
organic beings; and it was shown, by the same method of taking the existing
most imperfect series, that we ought not at once to reject the theory, because
we cannot trace the transitional stages in such organs, or conjecture the
transitional habits of such individual species.
In the Second Part{511} the direct evidence of allied forms having
descended from the same stock was discussed. It was shown that this theory
requires a long series of intermediate forms between the species and groups
in the same classes—forms not directly intermediate between existing
species, but intermediate with a common parent. It was admitted that if
even all the preserved fossils and existing species were collected, such a
series would be far from being formed; but it was shown that we have not
good evidence that the oldest known deposits are contemporaneous with the
first appearance of living beings; or that the several subsequent formations
are nearly consecutive; or that any one formation preserves a nearly perfect
fauna of even the hard marine organisms, which lived in that quarter of the
world. Consequently, we have no reason to suppose that more than a small
fraction of the organisms which have lived at any one period have ever been
preserved; and hence that we ought not to expect to discover the fossilised
sub-varieties between any two species. On the other hand, the evidence,
though extremely imperfect, drawn from fossil remains, as far as it does go,
is in favour of such a series of organisms having existed as that required.
This want of evidence of the past existence of almost infinitely numerous
intermediate forms, is, I conceive, much the weightiest difficulty{512} on the

theory of common descent; but I must think that this is due to ignorance
necessarily resulting from the imperfection of all geological records.
In the fifth chapter it was shown that new species gradually{513} appear,
and that the old ones gradually disappear, from the earth; and this strictly
accords with our theory. The extinction of species seems to be preceded by
their rarity; and if this be so, no one ought to feel more surprise at a species
being exterminated than at its being rare. Every species which is not
increasing in number must have its geometrical tendency to increase
checked by some agency seldom accurately perceived by us. Each slight
increase in the power of this unseen checking agency would cause a
corresponding decrease in the average numbers of that species, and the
species would become rarer: we feel not the least surprise at one species of
a genus being rare and another abundant; why then should we be surprised
at its extinction, when we have good reason to believe that this very rarity is
its regular precursor and cause.
In the sixth chapter the leading facts in the geographical distribution of
organic beings were considered—namely, the dissimilarity in areas widely
and effectually separated, of the organic beings being exposed to very
similar conditions (as for instance, within the tropical forests of Africa and
America, or on the volcanic islands adjoining them). Also the striking
similarity and general relations of the inhabitants of the same great
continents, conjoined with a lesser degree of dissimilarity in the inhabitants
living on opposite sides of the barriers intersecting it—whether or not these
opposite sides are exposed to similar conditions. Also the dissimilarity,
though in a still lesser degree, in the inhabitants of different islands in the
same archipelago, together with their similarity taken as a whole with the
inhabitants of the nearest continent, whatever its character may be. Again,
the peculiar relations of Alpine floras; the absence of mammifers on the
smaller isolated islands; and the comparative fewness of the plants and
other organisms on islands with diversified stations; the connection between
the possibility of occasional transportal from one country to another, with
an affinity, though not identity, of the organic beings inhabiting them. And
lastly, the clear and striking relations between the living and the extinct in
the same great divisions of the world; which relation, if we look very far
backward, seems to die away. These facts, if we bear in mind the geological
changes in progress, all simply follow from the proposition of allied organic

beings having lineally descended from common parent-stocks. On the
theory of independent creations they must remain, though evidently
connected together, inexplicable and disconnected.
In the seventh chapter, the relationship or grouping of extinct and recent
species; the appearance and disappearance of groups; the ill-defined objects
of the natural classification, not depending on the similarity of organs
physiologically important, not being influenced by adaptive or analogical
characters, though these often govern the whole economy of the individual,
but depending on any character which varies least, and especially on the
forms through which the embryo passes, and, as was afterwards shown, on
the presence of rudimentary and useless organs. The alliance between the
nearest species in distinct groups being general and not especial; the close
similarity in the rules and objects in classifying domestic races and true
species. All these facts were shown to follow on the natural system being a
genealogical system.
In the eighth chapter, the unity of structure throughout large groups, in
species adapted to the most different lives, and the wonderful
metamorphosis (used metaphorically by naturalists) of one part or organ
into another, were shown to follow simply on new species being produced
by the selection and inheritance of successive small changes of structure.
The unity of type is wonderfully manifested by the similarity of structure,
during the embryonic period, in the species of entire classes. To explain this
it was shown that the different races of our domestic animals differ less,
during their young state, than when full grown; and consequently, if species
are produced like races, the same fact, on a greater scale, might have been
expected to hold good with them. This remarkable law of nature was
attempted to be explained through establishing, by sundry facts, that slight
variations originally appear during all periods of life, and that when
inherited they tend to appear at the corresponding period of life; according
to these principles, in several species descended from the same parent-
stock, their embryos would almost necessarily much more closely resemble
each other than they would in their adult state. The importance of these
embryonic resemblances, in making out a natural or genealogical
classification, thus becomes at once obvious. The occasional greater
simplicity of structure in the mature animal than in the embryo; the
gradation in complexity of the species in the great classes; the adaptation of

the larvæ of animals to independent powers of existence; the immense
difference in certain animals in their larval and mature states, were all
shown on the above principles to present no difficulty.
In the «ninth» chapter, the frequent and almost general presence of
organs and parts, called by naturalists abortive or rudimentary, which,
though formed with exquisite care, are generally absolutely useless «was
considered». «These structures,» though sometimes applied to uses not
normal,—which cannot be considered as mere representative parts, for they
are sometimes capable of performing their proper function,—which are
always best developed, and sometimes only developed, during a very early
period of life,—and which are of admitted high importance in classification,
—were shown to be simply explicable on our theory of common descent.

Why do we wish to reject the theory of common descent?
Thus have many general facts, or laws, been included under one
explanation; and the difficulties encountered are those which would
naturally result from our acknowledged ignorance. And why should we not
admit this theory of descent{514}? Can it be shown that organic beings in a
natural state are all absolutely invariable? Can it be said that the limit of
variation or the number of varieties capable of being formed under
domestication are known? Can any distinct line be drawn between a race
and a species? To these three questions we may certainly answer in the
negative. As long as species were thought to be divided and defined by an
impassable barrier of sterility, whilst we were ignorant of geology, and
imagined that the world was of short duration, and the number of its past
inhabitants few, we were justified in assuming individual creations, or in
saying with Whewell that the beginnings of all things are hidden from man.
Why then do we feel so strong an inclination to reject this theory—
especially when the actual case of any two species, or even of any two
races, is adduced—and one is asked, have these two originally descended
from the same parent womb? I believe it is because we are always slow in
admitting any great change of which we do not see the intermediate steps.
The mind cannot grasp the full meaning of the term of a million or hundred
million years, and cannot consequently add up and perceive the full effects
of small successive variations accumulated during almost infinitely many
generations. The difficulty is the same with that which, with most

geologists, it has taken long years to remove, as when Lyell propounded
that great valleys{515} were hollowed out [and long lines of inland cliffs had
been formed] by the slow action of the waves of the sea. A man may long
view a grand precipice without actually believing, though he may not deny
it, that thousands of feet in thickness of solid rock once extended over many
square miles where the open sea now rolls; without fully believing that the
same sea which he sees beating the rock at his feet has been the sole
removing power.
Shall we then allow that the three distinct species of rhinoceros{516}
which separately inhabit Java and Sumatra and the neighbouring mainland
of Malacca were created, male and female, out of the inorganic materials of
these countries? Without any adequate cause, as far as our reason serves,
shall we say that they were merely, from living near each other, created very
like each other, so as to form a section of the genus dissimilar from the
African section, some of the species of which section inhabit very similar
and some very dissimilar stations? Shall we say that without any apparent
cause they were created on the same generic type with the ancient woolly
rhinoceros of Siberia and of the other species which formerly inhabited the
same main division of the world: that they were created, less and less
closely related, but still with interbranching affinities, with all the other
living and extinct mammalia? That without any apparent adequate cause
their short necks should contain the same number of vertebræ with the
giraffe; that their thick legs should be built on the same plan with those of
the antelope, of the mouse, of the hand of the monkey, of the wing of the
bat, and of the fin of the porpoise. That in each of these species the second
bone of their leg should show clear traces of two bones having been
soldered and united into one; that the complicated bones of their head
should become intelligible on the supposition of their having been formed
of three expanded vertebræ; that in the jaws of each when dissected young
there should exist small teeth which never come to the surface. That in
possessing these useless abortive teeth, and in other characters, these three
rhinoceroses in their embryonic state should much more closely resemble
other mammalia than they do when mature. And lastly, that in a still earlier
period of life, their arteries should run and branch as in a fish, to carry the
blood to gills which do not exist. Now these three species of rhinoceros
closely resemble each other; more closely than many generally

acknowledged races of our domestic animals; these three species if
domesticated would almost certainly vary, and races adapted to different
ends might be selected out of such variations. In this state they would
probably breed together, and their offspring would possibly be quite, and
probably in some degree, fertile; and in either case, by continued crossing,
one of these specific forms might be absorbed and lost in another. I repeat,
shall we then say that a pair, or a gravid female, of each of these three
species of rhinoceros, were separately created with deceptive appearances
of true relationship, with the stamp of inutility on some parts, and of
conversion in other parts, out of the inorganic elements of Java, Sumatra
and Malacca? or have they descended, like our domestic races, from the
same parent-stock? For my own part I could no more admit the former
proposition than I could admit that the planets move in their courses, and
that a stone falls to the ground, not through the intervention of the
secondary and appointed law of gravity, but from the direct volition of the
Creator.
Before concluding it will be well to show, although this has incidentally
appeared, how far the theory of common descent can legitimately be
extended{517}. If we once admit that two true species of the same genus can
have descended from the same parent, it will not be possible to deny that
two species of two genera may also have descended from a common stock.
For in some families the genera approach almost as closely as species of the
same genus; and in some orders, for instance in the monocotyledonous
plants, the families run closely into each other. We do not hesitate to assign
a common origin to dogs or cabbages, because they are divided into groups
analogous to the groups in nature. Many naturalists indeed admit that all
groups are artificial; and that they depend entirely on the extinction of
intermediate species. Some naturalists, however, affirm that though driven
from considering sterility as the characteristic of species, that an entire
incapacity to propagate together is the best evidence of the existence of
natural genera. Even if we put on one side the undoubted fact that some
species of the same genus will not breed together, we cannot possibly admit
the above rule, seeing that the grouse and pheasant (considered by some
good ornithologists as forming two families), the bull-finch and canary-bird
have bred together.

No doubt the more remote two species are from each other, the weaker
the arguments become in favour of their common descent. In species of two
distinct families the analogy, from the variation of domestic organisms and
from the manner of their intermarrying, fails; and the arguments from their
geographical distribution quite or almost quite fails. But if we once admit
the general principles of this work, as far as a clear unity of type can be
made out in groups of species, adapted to play diversified parts in the
economy of nature, whether shown in the structure of the embryonic or
mature being, and especially if shown by a community of abortive parts, we
are legitimately led to admit their community of descent. Naturalists dispute
how widely this unity of type extends: most, however, admit that the
vertebrata are built on one type; the articulata on another; the mollusca on a
third; and the radiata on probably more than one. Plants also appear to fall
under three or four great types. On this theory, therefore, all the organisms
yet discovered are descendants of probably less than ten parent-forms.

Conclusion.
My reasons have now been assigned for believing that specific forms
are not immutable creations{518}. The terms used by naturalists of affinity,
unity of type, adaptive characters, the metamorphosis and abortion of
organs, cease to be metaphorical expressions and become intelligible facts.
We no longer look at an organic being as a savage does at a ship{519} or other
great work of art, as at a thing wholly beyond his comprehension, but as a
production that has a history which we may search into. How interesting do
all instincts become when we speculate on their origin as hereditary habits,
or as slight congenital modifications of former instincts perpetuated by the
individuals so characterised having been preserved. When we look at every
complex instinct and mechanism as the summing up of a long history of
contrivances, each most useful to its possessor, nearly in the same way as
when we look at a great mechanical invention as the summing up of the
labour, the experience, the reason, and even the blunders of numerous
workmen. How interesting does the geographical distribution of all organic
beings, past and present, become as throwing light on the ancient geography
of the world. Geology loses glory{520} from the imperfection of its archives,
but it gains in the immensity of its subject. There is much grandeur in
looking at every existing organic being either as the lineal successor of
some form now buried under thousands of feet of solid rock, or as being the

co-descendant of that buried form of some more ancient and utterly lost
inhabitant of this world. It accords with what we know of the laws
impressed by the Creator{521} on matter that the production and extinction of
forms should, like the birth and death of individuals, be the result of
secondary means. It is derogatory that the Creator of countless Universes
should have made by individual acts of His will the myriads of creeping
parasites and worms, which since the earliest dawn of life have swarmed
over the land and in the depths of the ocean. We cease to be astonished{522}
that a group of animals should have been formed to lay their eggs in the
bowels and flesh of other sensitive beings; that some animals should live by
and even delight in cruelty; that animals should be led away by false
instincts; that annually there should be an incalculable waste of the pollen,
eggs and immature beings; for we see in all this the inevitable consequences
of one great law, of the multiplication of organic beings not created
immutable. From death, famine, and the struggle for existence, we see that
the most exalted end which we are capable of conceiving, namely, the
creation of the higher animals{523}, has directly proceeded. Doubtless, our
first impression is to disbelieve that any secondary law could produce
infinitely numerous organic beings, each characterised by the most
exquisite workmanship and widely extended adaptations: it at first accords
better with our faculties to suppose that each required the fiat of a Creator.
There{524} is a [simple] grandeur in this view of life with its several powers
of growth, reproduction and of sensation, having been originally breathed
into matter under a few forms, perhaps into only one{525}, and that whilst
this planet has gone cycling onwards according to the fixed laws of gravity
and whilst land and water have gone on replacing each other—that from so
simple an origin, through the selection of infinitesimal varieties, endless
forms most beautiful and most wonderful have been evolved.

INDEX

For the names of Authors, Birds, Mammals (including names of classes) and Plants, see sub-
indexes under Authors, Birds, Mammals and Plants.

Acquired characters, see Characters
Affinities and classification, 35
America, fossils, 177
Analogy, resemblance by, 36, 82, 199, 205, 211
Animals, marine, preservation of as fossils, 25, 139, 141;
—marine distribution, 155, 196
Australia, fossils, 177
Authors, Names of:—
Ackerman on hybrids, 11;
Bakewell, 9, 91;
Bateson, W., xxix, 69 n., 217;
Bellinghausen, 124;
Boitard and Corbié, 106 n.;
Brougham, Lord, 17, 117;
Brown, R., 233;
Buckland on fossils, 24, 137, 145 n.;
Buffon on woodpecker, 6;
Bunbury (Sir H.), rules for selection, 67;
Butler, S., 116 n.;
d’Archiac, 146 n.;
Darwin, C., origin of his evolutionary views, xi-xv;
—on Forbes’ theory, 30;
—his Journal of Researches quoted, 67 n., 168 n.;
—his Cross-and Self-Fertilisation, 69 n., 103 n.;
—on crossing Chinese and common goose, 72 n.;
Darwin, Mrs, letter to, xxvi;
Darwin, F., on Knight’s Law, 70 n.;
Darwin, R. W., fact supplied by, 42 n., 223;
Darwin and Wallace, joint paper by, xxiv, 42 n.;
De Candolle, 7, 47, 87, 204, 238;
D’Orbigny, 124, 179 n.;
Ehrenberg, 146 n.;
Ewart on telegony, 108 n.;
Falconer, 167;
Forbes, E., xxvii, 30, 146 n., 163 n., 165 n.;
Gadow, Dr, xxix;
Gärtner, 98, 107;
Goebel on Knight’s Law, 70 n.;
Gould on distribution, 156;
Gray, Asa, letter to, publication of in Linnean paper explained, xxiv;
Henslow, G., on evolution without selection, 63 n.;
Henslow, J. S., xxvii;
Herbert on hybrids, 12, 98;
—sterility of crocus, 99 n.;
Hering, 116 n.;
Hogg, 115 n.;
Holland, Dr, 223;

Hooker, J. D., xxvii, xxviii, 153 n.;
—on Insular Floras, 161, 164, 167;
Huber, P., 118;
Hudson on woodpecker, 131 n.;
Humboldt, 71, 166;
Hunter, W., 114;
Hutton, 27, 138;
Huxley, 134 n.;
—on Darwin, xi, xii, xiv;
—on Darwin’s Essay of 1844, xxviii, 235;
Judd, xi, xiii, xxix, 28, 141 n.;
Knight, A., 3 n., 65, xi;
—on Domestication, 77;
Knight-Darwin Law, 70 n.;
Kölreuter, 12, 97, 98, 104, 232;
Lamarck, 42 n., 47, 82, 146, 200;
—reasons for his belief in mutability, 197;
Lindley, 101;
Linnean Society, joint paper, see Darwin and Wallace;
Linnæus on sterility of Alpine plants, 101;
—on generic characters, 201;
Lonsdale, 145 n.;
Lyell, xxvii, 134 n., 138, 141 and n., 146 n., 159, 171, 173, 178;
—his doctrine carried to an extreme, 26;
—his geological metaphor, 27 n., 141;
—his uniformitarianism, 53 n.;
—his views on imperfection of geological record, 27;
Macculloch, 124 n.;
Macleay, W. S., 202;
Magendie, 117;
Malthus, xv, 7, 88, 90;
Marr, Dr, xxix;
Marshall, 65;
—on sheep and cattle, 78 and n.;
—on horns of cattle, 207;
Mivart, criticisms, 128 n.;
Mozart as a child, his skill on the piano compared to instinct, 19 n.;
Müller on consensual movements, 113;
—on variation under uniform conditions, (2), 62;
—on recapitulation theory, 219;
Murchison, 145 n.;
Newton, Alfred, 132 n.;
Owen, R., xxvii, 219;
Pallas, 68, 69;
Pennant, 93 n.;
Pliny on selection, 67;
Poeppig, 113 n.;
Prain, Col., xxix;
Rengger, sterility, 100;
Richardson, 132 n.;

Rutherford, H. W., xxix;
St Hilaire on races of dogs, 106;
—on sterility of tame and domestic animals, 12, 100;
Smith, Jordan, 140;
Sprengel, 233;
Stapf, Dr, xxix;
Strickland, xxvii;
Suchetet, 97 n.;
Thiselton-Dyer, Sir W., xxix, 167;
Wallace, xxiv, xxix, 30, 170 n.;
Waterhouse, 125, 126;
Western, Lord, 9, 65, 91;
Whewell, xxviii, 200;
Woodward, H. B., 145 n.;
Wrangel, 119 n.;
Zacharias, Darwin’s letter to, xv

Barriers and distribution, 30, 154, 157, 178
Bees, 113, 117;
combs of Hive-bee, 19, 121, 125, 126
Beetles, abortive wings of, 45
Birds, transporting seeds, 169;
feeding young with food different to their own, 19, 126;
migration, 123, 124;
nests, 120, 121, 122, 126;
of Galapagos, 19, 159;
rapid increase, 88;
song, 117
Birds, Names of:—
Apteryx, 45, 236;
Duck, 46, 61, 65, 128, 224 n.;
Fowl, domestic, 59, 82 n., 97, 113, 114, 217;
Goose, 72;
—periodic habit, 124 n.;
Grouse, hybridised, 97, 102;
Guinea-fowl, 79;
Hawk, sterility, 79;
—periodic habit, 124;
Opetiorynchus, 83;
Orpheus, 31;
Ostrich, distribution of, 158;
Owl, white barn, 82;
Partridge, infertility of, 102;
Peacock, 79, 97, 102;
Penguin, 128 n., 237;
Petrel, 128 n.;
Pheasant, 97, 102;
Pigeon, 66, 82, 110 n., 113, 114, 116, 117, 129, 135; see Wood-pigeon;
Rhea, 158;
Robins, increase in numbers, 88, 90;

Rock-thrush of Guiana, 93;
Swan, species of, 105;
Tailor-bird, 18, 118;
Turkey, Australian bush-turkey, 121 n., 122;
Tyrannus, 31;
Water-ouzel, 18 n., 120;
Woodcock, loss of migratory instinct, 120;
Woodpecker, 6, 16, 128 n., 148;
—in treeless lands, 16, 131;
Wood-pigeon, 122;
Wren, gold-crested, 120;
—willow, 105, 148
Breeds, domestic, parentage of, 71
Brothers, death of by same peculiar disease in old age, 42 n., 44 n., 223
Bud variation, 58; see Sports
Butterfly, cabbage, 127

Catastrophes, geological, 145, 147
Caterpillars, food, 126, 127
Characters, acquired, inheritance of, 1, 57, 60, 225;
—congenital, 60;
—fixed by breeding, 61;
—mental, variation in, 17, 112, 119;
—running through whole groups, 106;
—useless for classification, 199
Cirripedes, 201, 229
Classification, natural system of, 35, 199, 206, 208;
—by any constant character, 201;
—relation of, to geography, 202;
—a law that members of two distinct groups resemble each other not specifically but
generally, 203, 212;
—of domestic races, 204;
—rarity and extinction in relation to, 210
Compensation, law of, 106
Conditions, direct, action of, 1, 57 n., 62, 65;
—change of, analogous to crossing, 15, 77 n., 105;
—accumulated effects of, 60, 78;
—affecting reproduction, 1, 4, 78, 99;
—and geographical distribution, 152
Continent originating as archipelago, bearing of on distribution, 189
Cordillera, as channel of migration, 34 n., 191
Correlation, 76
Creation, centres of, 168, 192
Crocodile, 146
Cross-and Self-Fertilisation, early statement of principles of, 15, 69 n., 103 n.
Crossing, swamping effect of, 2, 69, 96;
—of bisexual animals and hermaphrodite plants, 2;
—analogous to change in conditions, 3, 15, 69;
—in relation to breeds, 68;
—in plants, adaptations for, 70

Death, feigned by insects, 123
Difficulties, on theory of evolution, 15, 121, 128, 134
Disease, hereditary, 43 n., 58, 222
Distribution, geographical, 29, 31, 151, 174, 177;
—in space and time, subject to same laws, 155;
—occasional means of (seeds, eggs, &c.), 169
Disuse, inherited effects of, 46, 57
Divergence, principle of, xxv, 37 n., 145 n., 208 n.
Domestication, variation under, 57, 62;
—accumulated effects of, 75, 78;
—analysis of effects of, 76, 83

Ears, drooping, 236
Elevation, geological, favouring birth of new species, 32, 34 n., 35 n., 185-189;
—alternating with subsidence, importance of for evolution, 33, 190;
—bad for preservation of fossils, 194
Embryo, branchial arches of, 42, 220;
—absence of special adaptation in, 42, 44 n., 220, 228;
—less variable than parent, hence importance of embryology for classification, 44 n.,
229;
—alike in all vertebrates, 42, 218;
—occasionally more complicated than adult, 219, 227
Embryology, 42, 218;
its value in classification, 45, 200;
law of inheritance at corresponding ages, 44 n., 224;
young of very distinct breeds closely similar, 44 n., 44
Ephemera, selection falls on larva, 87 n.
Epizoa, 219
Essay of 1842, question as to date of, xvi;
description of ms., xx;
compared with the Origin, xx
Essay of 1844, writing of, xvi;
compared with that of 1842 and with the Origin, xxii
Evolution, theory of, why do we tend to reject it, 248
Expression, inheritance of, 114
Extinction, 23, 147, 192;
locally sudden, 145;
continuous with rarity, 147, 198
Extinction and rarity, 198
Eye, 111 n., 128, 129, 130

Faculty, in relation to instinct, 123
Faunas, alpine, 30, 170, 188;
of Galapagos, 31 n., 82, 159;
insular-alpine very peculiar, 188;
insular, 159, 160
Fauna and flora, of islands related to nearest land, 187
Fear of man, inherited, 17, 113
Fertility, interracial, 103, 104

Fish, colours of, 130, 131;
eggs of carried by water-beetle, 169;
flying, 128 n.;
—transported by whirlwind, 169
Floras, alpine, 162;
of oceanic islands, 162;
alpine, related to surrounding lowlands, 162;
alpine, identity of on distant mountains, 163;
alpine resembling arctic, 164;
arctic relation to alpine, 164
Flower, morphology of, 39, 216;
degenerate under domestication if neglected, 58;
changed by selection, 66
Fly, causing extinction, 149
Flying, evolution of, 16, 131
Food, causing variations, 1, 58, 77, 78
Formation (geological) evidence from Tertiary system, 144;
(geological), groups of species appear suddenly in Secondary, 26, 144;
Palæozoic, if contemporary with beginning of life, author's theory false, 138
Formations, most ancient escape denudation in conditions unfavourable to life, 25, 139
Forms, transitional, 24, 35 n., 136, 142, 194;
on rising land, 196;
indirectly intermediate, 24, 135
Fossils, Silurian, not those which first existed in the world, 26, 138;
falling into or between existing groups and indirectly intermediate, 24, 137;
conditions favourable to preservation, not favourable to existence of much life, 25, 139,
141
Fruit, attractive to animals, 130

Galapagos Islands and Darwin’s views, xiv;
physical character of in relation to fauna, 31 n., 159
Galapagos Islands, fauna, 31 n., 82
Gasteropods, embryology, 218
Genera, crosses between, 11, 97;
wide ranging, has wide ranging species, 155;
origin of, 209
Geography, in relation to geology, 31 n., 174, 177
Geographical distribution, see Distribution
Geology, as producing changed conditions, 31;
evidence from, 22, 133;
“destroys geography,” 31 n.
Glacial period, effect of on distribution of alpine and arctic plants, 165

Habit in relation to instinct, 17, 113, 115, 116
Habits in animals taught by parent, 18
Heredity, see Inheritance
Homology of limbs, 38, 214
Homology, serial, 39, 215
Hybrid, fowls and grouse, 11;
fowl and peacock, 97;

pheasant and grouse, 97;
Azalea and Rhododendron, 97
Hybrids, gradation in sterility of, 11, 72, 97;
sterility of not reciprocal, 97;
variability of, 78;
compared and contrasted with mongrel, 107

Individual, meaning of term, 58
Inheritance of acquired characters, see Character
Inheritance, delayed or latent, 43, 44 n., 223;
of character at a time of life corresponding to that at which it first appeared, 43, 44 n.,
223;
germinal, 44, 222, 223
Insect, adapted to fertilise flowers, 87;
feigning death, 123;
metamorphosis, 129;
variation in larvæ, 223
Instinct, variation in, 17, 112;
and faculty, 18, 123;
guided by reason, 18, 19, 118;
migratory, 19;
migratory, loss of by woodcocks, 120;
migratory, origin of, 125;
due to germinal variation rather than habit, 116;
requiring education for perfection, 117;
characterised by ignorance of end: e.g. butterflies laying eggs, 17, 118;
butterflies laying eggs on proper plant, 118, 127;
instinct, natural selection applicable to, 19, 120
Instinct, for finding the way, 124;
periodic, i.e. for lapse of time, 124;
comb-making of bee, 125;
birds feeding young, 19, 126;
nest-building, gradation in, 18, 120, 121, 122;
instincts, complex, difficulty in believing in their evolution, 20, 121
Intermediate forms, see Forms
Island, see Elevation, Fauna, Flora
Island, upheaved and gradually colonised, 184
Islands, nurseries of new species, 33, 35 n., 185, 189
Isolation, 32, 34 n., 64, 95, 183, 184

Lepidosiren, 140 n., 212
Limbs, vertebrate, of one type, 38, 216

Mammals, arctic, transported by icebergs, 170;
distribution, 151, 152, 193;
distribution of, ruled by barriers, 154;
introduced by man on islands, 172;
not found on oceanic islands, 172;
relations in time and space, similarity of, 176;
of Tertiary period, relation of to existing forms in same region, 174

Mammals, Names of:—
Antelope, 148;
Armadillo, 174;
Ass, 79, 107, 172;
Bat, 38, 123, 128 n., 131, 132, 214;
Bear, sterile in captivity, 100;
—whale-like habit, 128 n.;
Bizcacha, 168, 203, 212;
Bull, mammæ of, 232;
Carnivora, law of compensation in, 106;
Cats, run wild at Ascension, 172;
—tailless, 60;
Cattle, horns of, 75, 207;
—increase in S. America, 90;
—Indian, 205;
—Niata, 61, 73;
—suffering in parturition from too large calves, 75;
Cheetah, sterility of, 100 and n.;
Chironectes, 199;
Cow, abortive mammæ, 232;
Ctenomys, see Tuco-tuco;
Dog, 106, 114;
—in Cuba, 113 and n.;
—mongrel breed in oceanic islands, 70;
—difference in size a bar to crossing, 97;
—domestic, parentage of, 71, 72, 73;
—drooping ears, 236;
—effects of selection, 66;
—inter-fertile, 14;
—long-legged breed produced to catch hares, 9, 10, 91, 92;
—of savages, 67;
—races of resembling genera, 106, 204;
—Australian, change of colour in, 61;
—bloodhound, Cuban, 204;
—bull-dog, 113;
—foxhound, 114, 116;
—greyhound and bull-dog, young of resembling each other, 43, 44 n., 225;
—pointer, 114, 115, 116, 117, 118;
—retriever, 118 n.;
—setter, 114;
—shepherd-dog and harrier crossed, instinct of, 118, 119;
—tailless, 60;
—turnspit, 66;
Echidna, 82 n.;
Edentata, fossil and living in S. America, 174;
Elephant, sterility of, 12, 100;
Elk, 125;
Ferret, fertility of, 12, 102;
Fox, 82, 173, 181;
Galeopithecus, 131 n.;

Giraffe, fossil, 177;
—tail, 128 n.;
Goat, run wild at Tahiti, 172;
Guanaco, 175;
Guinea-pig, 69;
Hare, S. American, 158 n.;
Hedgehog, 82 n.;
Horse, 67, 113, 115, 148, 149;
—checks to increase, 148, 149;
—increase in S. America, 90;
—malconformations and lameness inherited, 58;
—parentage, 71, 72;
—stripes on, 107;
—young of cart-horse and racehorse resembling each other, 43;
Hyena, fossil, 177;
Jaguar, catching fish, 132;
Lemur, flying, 131 n.;
Macrauchenia, 137;
Marsupials, fossil in Europe, 175 n., 177;
—pouch bones, 232, 237;
Mastodon, 177;
Mouse, 153, 155;
—enormous rate of increase, 89, 90;
Mule, occasionally breeding, 97, 102;
Musk-deer, fossil, 177;
Mustela vison, 128 n., 132 n.;
Mydas, 170;
Mydaus, 170;
Nutria, see Otter;
Otter, 131, 132, 170;
—marsupial, 199, 205, 211;
Pachydermata, 137;
Phascolomys, 203, 212;
Pig, 115, 217;
—in oceanic islands, 70;
—run wild at St Helena, 172;
Pole-cat, aquatic, 128 n., 132 _n._;
Porpoise, paddle of, 38, 214;
Rabbit, 74, 113, 236;
Rat, Norway, 153;
Reindeer, 125;
Rhinoceros, 148;
—abortive teeth of, 45, 231;
—three oriental species of, 48, 249;
Ruminantia, 137 and n.;
Seal, 93 n., 131;
Sheep, 68, 78, 117, 205;
—Ancon variety, 59, 66, 73;
—inherited habit of returning home to lamb, 115;
—transandantes of Spain, their migratory instinct, 114, 117, 124 n.;

Squirrel, flying, 131;
Tapir, 135, 136;
Tuco-tuco, blindness of, 46, 236;
Whale, rudimentary teeth, 45, 229;
Wolf, 71, 72, 82;
Yak, 72
Metamorphosis, literal not metaphorical, 41, 72
Metamorphosis, e.g. leaves into petals, 215
Migrants to new land, struggle among, 33, 185
Migration, taking the place of variation, 188
Monstrosities, as starting-points of breeds, 49, 59;
their relation to rudimentary organs, 46, 234
Morphology, 38, 215;
terminology of, no longer metaphorically used, 41, 217
Mutation, see Sports

Natural selection, see Selection
Nest, bird’s, see Instinct

Ocean, depth of, and fossils, 25, 195
Organisms, gradual introduction of new, 23, 144;
extinct related to, existing in the same manner as representative existing ones to each
other, 33, 192;
introduced, beating indigenes, 153;
dependent on other organisms rather than on physical surroundings, 185;
graduated complexity in the great classes, 227;
immature, how subject to natural selection, 42, 220, 228;
all descended from a few parent-forms, 52, 252
Organs, perfect, objection to their evolution, 15, 128;
distinct in adult life, indistinguishable in embryo, 42, 218;
rudimentary, 45, 231, 232, 233;
rudimentary, compared to monstrosities, 46, 234;
rudimentary, caused by disuse, 46, 235;
rudimentary, adapted to new ends, 47, 237
Orthogenesis, 241 n.
Oscillation of level in relation to continents, 33, 34 n., 241

Pallas, on parentage of domestic animals, 71
Pampas, imaginary case of farmer on, 32, 184
Perfection, no inherent tendency towards, 227
Plants, see also Flora;
fertilisation, 70;
migration of, to arctic and antarctic regions, 167;
alpine and arctic, migration of, 31, 166;
alpine, characters common to, 162;
alpine, sterility of, 13, 101
Plants, Names of:—
Ægilops, 58 n.;
Artichoke (Jerusalem), 79;
Ash, weeping, seeds of, 61;

Asparagus, 79;
Azalea, 13, 59, 97;
Cabbage, 109, 135, 204;
Calceolaria, 11, 99;
Cardoon, 153;
Carrot, variation of, 58 n.;
Chrysanthemum, 59;
Crinum, 11, 99;
Crocus, 96, 99 n.;
Cucubalus, crossing, 232;
Dahlia, 21, 59, 63, 69, 74, 110;
Foxglove, 82;
Gentian, colour of flower, 107 n.;
Geranium, 102;
Gladiolus, crossed, ancestry of, 11;
Grass, abortive flowers, 233;
Heath, sterility, 96;
Hyacinth, colours of, 106;
—feather-hyacinth, 229;
Juniperus, hybridised, 97;
Laburnum, peculiar hybrid, 108;
Lilac, sterility of, 13, 100;
Marigold, style of, 47, 233, 237;
Mistletoe, 6, 86, 87, 90 n.;
Nectarines on peach trees, 59;
Oxalis, colour of flowers of, 107 n.;
Phaseolus, cultivated form suffers from frost, 107;
Pine-apple, 207;
Poppy, Mexican, 154;
Potato, 69, 74, 110;
Rhododendron, 97, 99;
Rose, moss, 59;
—Scotch, 69;
Seakale, 79;
Sweet-william, 59;
Syringa, persica and chinensis, see Lilac;
Teazle, 129;
Thuja, hybridised, 97;
Tulips, "breaking" of, 58;
Turnip, Swedish and common, 205;
Vine, peculiar hybrid, 108;
Yew, weeping, seeds of, 61
Plasticity, produced by domestication, 1, 63
Plesiosaurus, loss of unity of type in, 41, 217
Pteropods, embryology, 218

Quadrupeds, extinction of large, 147
Quinary System, 202

Race, the word used as equivalent to variety, 94

Races, domestic, classification of, 204
Rarity, 28, 148;
and extinction, 28, 149, 210
Recapitulation theory, 42, 219, 230, 239
Record, geological, imperfection of, 26, 140
Regions, geographical, of the world, 29, 152, 174;
formerly less distinct as judged by fossils, 177
Resemblance, analogical, 36, 199
Reversion, 3, 64, 69, 74
“Roguing,” 3
Rudimentary organs, see Organs

Savages, domestic animals of, 67, 68, 96
Selection, human, 3, 63;
references to the practice of, in past times, 67;
great effect produced by, 3, 91;
necessary for the formation of breeds, 64;
methodical, effects of, 3, 65;
unconscious, 3, 67
Selection, natural, xvi, 7, 87;
natural compared to human, 85, 94, 224;
of instincts, 120, 120;
difficulty of believing, 15, 121, 128
Selection, sexual, two types of, 10, 92
Silk-worms, variation in larval state, 44 n., 223
Skull, morphology of, 39, 215
Species, representative, seen in going from N. to S. in a continent, 31 n., 156;
representative in archipelagoes, 187;
wide-ranging, 34 n., 146;
and varieties, difficulty of distinguishing, 4, 81, 197;
sterility of crosses between, supposed to be criterion, 11, 134;
gradual appearance and disappearance of, 23, 144;
survival of a few among many extinct, 146
Species, not created more than once, 168, 171, 191;
evolution of, compared to birth of individuals, 150, 198, 253;
small number in New Zealand as compared to the Cape, 171, 191;
persistence of, unchanged, 192, 199
Sports, 1, 58, 59, 64, 74, 95, 129, 186, 206, 224
Sterility, due to captivity, 12, 77 n., 100;
of various plants, 13, 101;
of species when crossed, 11, 23, 96, 99, 103;
produced by conditions, compared to sterility due to crossing, 101, 102
Struggle for life, 7, 91, 92, 148, 241
Subsidence, importance of, in relation to fossils, 25, 35 n., 7;
of continent leading to isolation of organisms, 190;
not favourable to birth of new species, 196
Swimming bladder, 16, 129
System, natural, is genealogical, 36, 208

Telegony, 108

Tibia and fibula, 48, 137
Time, enormous lapse of, in geological epochs, 25, 140
Tortoise, 146
Transitional forms, see Forms
Trigonia, 147 n., 199
Tree-frogs in treeless regions, 131
Type, unity of, 38, 214;
uniformity of, lost in Plesiosaurus, 217;
persistence of, in continents, 158, 178

Uniformitarian views of Lyell, bearing on evolution, 249
Use, inherited effects of, see Characters, acquired

Variability, as specific character, 83;
produced by change and also by crossing, 105
Variation, by Sports, see Sports;
under domestication, 1, 57, 63, 78;
due to causes acting on reproductive system, see Variation, germinal;
—germinal, 2, 43, 62, 222;
individual, 57 n.;
causes of, 1, 4, 57, 61;
due to crossing, 68, 69;
limits of, 74, 75, 82, 109;
small in state of nature, 4, 59 n., 81, 83;
results of without selection, 84;
—minute, value of, 91;
analogous in species of same genus, 107;
of mental attributes, 17, 112;
in mature life, 59, 224, 225
Varieties, minute, in birds, 82;
resemblance of to species, 81 n., 82, 105
Vertebrate skull, morphology of, 215

Wildness, hereditary, 113, 119

Footnotes
{1} See the extracts in Life and Letters of Charles Darwin, ii. p. 5.
{2} The second volume,—especially important in regard to Evolution,—reached
him in the autumn of 1832, as Prof. Judd has pointed out in his most interesting
paper in Darwin and Modern Science. Cambridge, 1909.
{3} Obituary Notice of C. Darwin, Proc. R. Soc. vol. 44. Reprinted in Huxley's
Collected Essays. See also Life and Letters of C. Darwin, ii. p. 179.
{4} See the extracts in the Life and Letters, ii. p. 5.
{5} Life and Letters, i. p. 82.
{6} Obituary Notice, loc. cit.
{7} Darwin and Modern Science.
{8} Huxley, Obituary, p. xi.
{9} In this citation the italics are mine.
{10} Journal of Researches, Ed. 1860, p. 394.
{11} F. Darwin’s Life of Charles Darwin (in one volume), 1892, p. 166.
{12} Life and Letters, i. p. 83.
{13} Life and Letters, ii. p. 8.
{14} Avestruz Petise, i.e. Rhea Darwini.
{15} A bird.
{16} Life and Letters, i. p. 84.
{17} It contains as a fact 231 pp. It is a strongly bound folio, interleaved with
blank pages, as though for notes and additions. His own ms. from which it was
copied contains 189 pp.
{18} Life and Letters, ii. p. 116.
{19} Life and Letters, ii. p. 10.
{20} Life and Letters, ii. p. 146.
{21} J. Linn. Soc. Zool. iii. p. 45.
{22} It is evident that Parts and Chapters were to some extent interchangeable
in the author’s mind, for p. 1 (of the ms. we have been discussing) is headed in

ink Chapter I, and afterwards altered in pencil to Part I.
{23} On p. 23 of the ms. of the Foundations is a reference to the “back of p. 21
bis”: this suggests that additional pages had been interpolated in the ms. and that
it may once have had 37 in place of 35 pp.
{24} Life and Letters, i. p. 153.
{25} Life and Letters, i. p. 84.
{26} In the footnotes to the Essay of 1844 attention is called to similar passages.
{27} Life and Letters, ii. p. 15.
{28} The passage is given in the Life and Letters, ii. p. 124.
{29} The extract consists of the section on Natural Means of Selection, p. 87.
{30} Life and Letters, i. p. 84.
{31} Life and Letters, ii. p. 18.
{32} Mrs Darwin’s brother.
{33} After Mr Strickland’s name comes the following sentence, which has been
erased, but remains legible. “Professor Owen would be very good; but I presume
he would not undertake such a work.”
{34} The words “several years ago, and” seem to have been added at a later
date.
{35} Life and Letters, ii. p. 9.
{36} Evidently a memorandum that an example should be given.
{37} The importance of exposure to new conditions for several generations is
insisted on in the Origin, Ed. i. p. 7, also p. 131. In the latter passage the author
guards himself against the assumption that variations are “due to chance,” and
speaks of “our ignorance of the cause of each particular variation.” These
statements are not always remembered by his critics.
{38} Cf. Origin, Ed. i. p. 10, vi. p. 9, “Young of the same litter, sometimes differ
considerably from each other, though both the young and the parents, as Müller
has remarked, have apparently been exposed to exactly the same conditions of
life.”
{39} This is paralleled by the conclusion in the Origin, Ed. i. p. 8, that “the most
frequent cause of variability may be attributed to the male and female
reproductive elements having been affected prior to the act of conception.”
{40} The meaning seems to be that there must be some variability in the liver
otherwise anatomists would not speak of the ‘beau ideal’ of that organ.
{41} The position of the following passage is uncertain. “If individuals of two
widely different varieties be allowed to cross, a third race will be formed—a
most fertile source of the variation in domesticated animals. «In the Origin, Ed.
i. p. 20 the author says that “the possibility of making distinct races by crossing

has been greatly exaggerated.”» If freely allowed, the characters of pure parents
will be lost, number of races thus «illegible» but differences «?» besides the
«illegible». But if varieties differing in very slight respects be allowed to cross,
such small variation will be destroyed, at least to our senses,—a variation
[clearly] just to be distinguished by long legs will have offspring not to be so
distinguished. Free crossing great agent in producing uniformity in any breed.
Introduce tendency to revert to parent form.”
{42} The swamping effect of intercrossing is referred to in the Origin, Ed. i. p.
103, vi. p. 126.
{43} A discussion on the intercrossing of hermaphrodites in relation to Knight’s
views occurs in the Origin, Ed. i. p. 96, vi. p. 119. The parallelism between
crossing and changed conditions is briefly given in the Origin, Ed. i. p. 267, vi.
p. 391, and was finally investigated in The Effects of Cross and Self-Fertilisation
in the Vegetable Kingdom, 1876.
{44} There is an article on the vis medicatrix in Brougham’s Dissertations,
1839, a copy of which is in the author’s library.
{45} This is the classification of selection into methodical and unconscious
given in the Origin, Ed. i. p. 33, vi. p. 38.
{46} This passage, and a similar discussion on the power of the Creator (p. 6),
correspond to the comparison between the selective capacities of man and
nature, in the Origin, Ed. i. p. 83, vi. p. 102.
{47} i.e. they are individually distinguishable.
{48} See Origin, Ed. i. p. 133, vi. p. 165.
{49} When the author wrote this sketch he seems not to have been so fully
convinced of the general occurrence of variation in nature as he afterwards
became. The above passage in the text possibly suggests that at this time he laid
more stress on sports or mutations than was afterwards the case.
{50} The author may possibly have taken the case of the woodpecker from
Buffon, Histoire Nat. des Oiseaux, T. vii. p. 3, 1780, where however it is treated
from a different point of view. He uses it more than once, see for instance
Origin, Ed. i. pp. 3, 60, 184, vi. pp. 3, 76, 220. The passage in the text
corresponds with a discussion on the woodpecker and the mistletoe in Origin,
Ed. i. p. 3, vi. p. 3.
{51} This illustration occurs in the Origin, Ed. i. pp. 90, 91, vi. pp. 110, 111.
{52} See Origin, Ed. i. p. 83, vi. p. 102, where the word Creator is replaced by
Nature.
{53} Note in the original. “Good place to introduce, saying reasons hereafter to
be given, how far I extend theory, say to all mammalia—reasons growing
weaker and weaker.”
{54} See Origin, Ed. i. pp. 62, 63, vi. p. 77, where similar reference is made to
De Candolle; for Malthus see Origin, p. 5.

{55} This may possibly refer to the amount of destruction going on. See Origin,
Ed. i. p. 68, vi. p. 84, where there is an estimate of a later date as to death-rate of
birds in winter. “Calculate robins” probably refers to a calculation of the rate of
increase of birds under favourable conditions.
{56} In the Origin, Ed. i. pp. 64, 65, vi. p. 80, he instances cattle and horses and
certain plants in S. America and American species of plants in India, and further
on, as unexpected effects of changed conditions, the enclosure of a heath, and
the relation between the fertilisation of clover and the presence of cats (Origin,
Ed. i. p. 74, vi. p. 91).
{57} Origin, Ed. i. p. 74, vi. p. 91. “It has been observed that the trees now
growing on ... ancient Indian mounds ... display the same beautiful diversity and
proportion of kinds as in the surrounding virgin forests.”
{58} The simile of the wedge occurs in the Origin, Ed. i. p. 67; it is deleted in
Darwin’s copy of the first edition: it does not occur in Ed. vi.
{59} In a rough summary at the close of the Essay, occur the words:—“Every
creature lives by a struggle, smallest grain in balance must tell.”
{60} Cf. Origin, Ed. i. p. 77, vi. p. 94.
{61} This is a repetition of what is given at p. 6.
{62} Compare Origin, Ed. i. p. 41, vi. p. 47. “I have seen it gravely remarked,
that it was most fortunate that the strawberry began to vary just when gardeners
began to attend closely to this plant. No doubt the strawberry had always varied
since it was cultivated, but the slight varieties had been neglected.”
{63} Here we have the two types of sexual selection discussed in the Origin, Ed.
i. pp. 88 et seq., vi. pp. 108 et seq.
{64} It is not obvious why the author objects to “chance” or “external conditions
making a woodpecker.” He allows that variation is ultimately referable to
conditions and that the nature of the connexion is unknown, i.e. that the result is
fortuitous. It is not clear in the original to how much of the passage the two ?
refer.
{65} The meaning is “That sterility is not universal is admitted by all.”
{66} See Var. under Dom., Ed. 2, i. p. 388, where the garden forms of Gladiolus
and Calceolaria are said to be derived from crosses between distinct species.
Herbert’s hybrid Crinums are discussed in the Origin, Ed. i. p. 250, vi. p. 370. It
is well known that the author believed in a multiple origin of domestic dogs.
{67} The argument from gradation in sterility is given in the Origin, Ed. i. pp.
248, 255, vi. pp. 368, 375. In the Origin, I have not come across the cases
mentioned, viz. crocus, heath, or grouse and fowl or peacock. For sterility
between closely allied species, see Origin, Ed. i. p. 257, vi. p. 377. In the present
essay the author does not distinguish between fertility between species and the
fertility of the hybrid offspring, a point on which he insists in the Origin, Ed. i.
p. 245, vi. p. 365.

{68} Ackermann (Ber. d. Vereins f. Naturkunde zu Kassel, 1898, p. 23) quotes
from Gloger that a cross has been effected between a domestic hen and a Tetrao
tetrix; the offspring died when three days old.
{69} No doubt the sexual cells are meant. I do not know on what evidence it is
stated that the mule has bred.
{70} The sentence is all but illegible. I think that the author refers to forms
usually ranked as varieties having been marked as species when it was found
that they were sterile together. See the case of the red and blue Anagallis given
from Gärtner in the Origin, Ed. i. p. 247, vi. p. 368.
{71} In the Origin, Ed. i. p. 258, where the author speaks of constitutional
differences in this connexion, he specifies that they are confined to the
reproductive system.
{72} The sensitiveness of the reproductive system to changed conditions is
insisted on in the Origin, Ed. i. p. 8, vi. p. 10.
The ferret is mentioned, as being prolific in captivity, in Var. under Dom., Ed. 2,
ii. p. 90.
{73} Lindley’s remark is quoted in the Origin, Ed. i. p. 9. Linnæus’ remark is to
the effect that Alpine plants tend to be sterile under cultivation (see Var. under
Dom., Ed. 2, ii. p. 147). In the same place the author speaks of peat-loving plants
being sterile in our gardens,—no doubt the American bog-plants referred to
above. On the following page (p. 148) the sterility of the lilac (Syringa persica
and chinensis) is referred to.
{74} The author probably means that the increase in the petals is due to a greater
food supply being available for them owing to sterility. See the discussion in Var.
under Dom., Ed. 2, ii. p. 151. It must be noted that doubleness of the flower may
exist without noticeable sterility.
{75} I have not come across this case in the author’s works.
{76} For the somewhat doubtful case of the cheetah (Felis jubata) see Var. under
Dom., Ed. 2, ii. p. 133. I do not know to what fact “pig in India” refers.
{77} This sentence should run “on which depends their incapacity to breed in
unnatural conditions.”
{78} This sentence ends in confusion: it should clearly close with the words
“refused to breed” in place of the bracket and the present concluding phrase.
{79} The author doubtless refers to the change produced by the summation of
variation by means of selection.
{80} The meaning of this sentence is made clear by a passage in the ms. of 1844:
—“Until man selects two varieties from the same stock, adapted to two climates
or to other different external conditions, and confines each rigidly for one or
several thousand years to such conditions, always selecting the individuals best
adapted to them, he cannot be said to have even commenced the experiment.”
That is, the attempt to produce mutually sterile domestic breeds.

{81} This passage is to some extent a repetition of a previous one and may have
been intended to replace an earlier sentence. I have thought it best to give both.
In the Origin, Ed. i. p. 141, vi. p. 176, the author gives his opinion that the
power of resisting diverse conditions, seen in man and his domestic animals, is
an example “of a very common flexibility of constitution.”
{82} In the Origin, Ed. i. Chs. i. and v., the author does not admit reproduction,
apart from environment, as being a cause of variation. With regard to the
cumulative effect of new conditions there are many passages in the Origin, Ed. i.
e.g. pp. 7, 12, vi. pp. 8, 14.
{83} As already pointed out, this is the important principle investigated in the
author’s Cross and Self-Fertilisation. Professor Bateson has suggested to me that
the experiments should be repeated with gametically pure individuals.
{84} In the Origin a chapter is given up to “difficulties on theory”: the
discussion in the present essay seems slight even when it is remembered how
small a space is here available. For Tibia &c. see p. 48.
{85} This may be interpreted “The general structure of a bat is the same as that
of non-flying mammals.”
{86} That is truly winged fish.
{87} The terrestrial woodpecker of S. America formed the subject of a paper by
Darwin, Proc. Zool. Soc., 1870. See Life and Letters, vol. iii. p. 153.
{88} The same proviso occurs in the Origin, Ed. i. p. 207, vi. p. 319.
{89} The tameness of the birds in the Galapagos is described in the Journal of
Researches (1860), p. 398. Dogs and rabbits are probably mentioned as cases in
which the hereditary fear of man has been lost. In the 1844 ms. the author states
that the Cuban feral dog shows great natural wildness, even when caught quite
young.
{90} In the Origin, Ed. i. p. 207, vi. p. 319, he refuses to define instinct. For
Lord Brougham’s definition see his Dissertations on Subjects of Science etc.,
1839, p. 27.
{91} See James Hogg (the Ettrick Shepherd), Works, 1865, Tales and Sketches,
p. 403.
{92} This refers to the tailor-bird making use of manufactured thread supplied to
it, instead of thread twisted by itself.
{93} Often lost applies to instinct: birds get wilder is printed in a parenthesis
because it was apparently added as an after-thought. Nest without roof refers to
the water-ousel omitting to vault its nest when building in a protected situation.
{94} In the ms. of 1844 is an interesting discussion on faculty as distinct from
instinct.
{95} At this date and for long afterwards the inheritance of acquired characters
was assumed to occur.

{96} Part II. is here intended: see the Introduction.
{97} The meaning is that the attitude assumed in shamming is not accurately like
that of death.
{98} This refers to the transandantes sheep mentioned in the ms. of 1844, as
having acquired a migratory instinct.
{99} In the Origin, Ed. i. p. 209, vi. p. 321, Mozart’s pseudo-instinctive skill in
piano-playing is mentioned. See Phil. Trans., 1770, p. 54.
{100} In the discussion on bees’ cells, Origin, Ed. i. p. 225, vi. p. 343, the author
acknowledges that his theory originated in Waterhouse’s observations.
{101} The hawfinch-and Sylvia-types are figured in the Journal of Researches,
p. 379. The discussion of change of form in relation to change of instinct is not
clear, and I find it impossible to suggest a paraphrase.
{102} I should interpret this obscure sentence as follows, “No such opposing
law is known, but in all works on the subject a law is (in flat contradiction to all
known facts) assumed to limit the possible amount of variation.” In the Origin,
the author never limits the power of variation, as far as I know.
{103} In Var. under Dom. Ed. 2, ii. p. 263, the Dahlia is described as showing
sensitiveness to conditions in 1841. All the varieties of the Dahlia are said to
have arisen since 1804 (ibid. i. p. 393).
{104} In the original ms. the heading is: Part III.; but Part II. is clearly intended;
for details see the Introduction. I have not been able to discover where § iv. ends
and § v. begins.
{105} This passage corresponds roughly to the conclusion of the Origin, see Ed.
i. p. 482, vi. p. 661.
{106} A similar passage occurs in the conclusion of the Origin, Ed. i. p. 481, vi.
p. 659.
{107} See Origin, Ed. i. p. 312, vi. p. 453.
{108} See Origin, Ed. i. pp. 280, 281, vi. p. 414. The author uses his experience
of pigeons for examples for what he means by intermediate; the instance of the
horse and tapir also occurs.
{109} The absence of intermediate forms between living organisms (and also as
regards fossils) is discussed in the Origin, Ed. i. pp. 279, 280, vi. p. 413. In the
above discussion there is no evidence that the author felt this difficulty so
strongly as it is expressed in the Origin, Ed. i. p. 299,—as perhaps “the most
obvious and gravest objection that can be urged against my theory.” But in a
rough summary written on the back of the penultimate page of the ms. he refers
to the geological evidence:—“Evidence, as far as it does go, is favourable,
exceedingly incomplete,—greatest difficulty on this theory. I am convinced not
insuperable.” Buckland’s remarks are given in the Origin, Ed. i. p. 329, vi. p.
471.

{110} That the evidence of geology, as far as it goes, is favourable to the theory
of descent is claimed in the Origin, Ed. i. pp. 343-345, vi. pp. 490-492. For the
reference to net in the following sentence, see Note 1, p. 48, {Link:Note 161} of
this Essay.
{111} See Origin, Ed. i. p. 288, vi. p. 422. “The remains that do become
embedded, if in sand and gravel, will, when the beds are upraised, generally be
dissolved by the percolation of rain-water.”
{112} The position of the following is not clear:—“Think of immense
differences in nature of European deposits,—without interposing new causes,—
think of time required by present slow changes, to cause, on very same area,
such diverse deposits, iron-sand, chalk, sand, coral, clay!”
{113} The paragraph which ends here is difficult to interpret. In spite of
obscurity it is easy to recognize the general resemblance to the discussion on the
importance of subsidence given in the Origin, Ed. i. pp. 290 et seq., vi. pp. 422
et seq.
{114} See Note 3, p. 27.
{115} Compare Origin, Ed. i. p. 298, vi. p. 437. “We shall, perhaps, best
perceive the improbability of our being enabled to connect species by numerous,
fine, intermediate, fossil links, by asking ourselves whether, for instance,
geologists at some future period will be able to prove that our different breeds of
cattle, sheep, horses, and dogs have descended from a single stock or from
several aboriginal stocks.”
{116} The sudden appearance of groups of allied species in the lowest known
fossiliferous strata is discussed in the Origin, Ed. i. p. 306, vi. p. 446. The
gradual appearance in the later strata occurs in the Origin, Ed. i. p. 312, vi. p.
453.
{117} Compare Origin, Ed. i. p. 307, vi. p. 448.
{118} I have interpreted as Sandstone a scrawl which I first read as Sea; I have
done so at the suggestion of Professor Judd, who points out that “footprints in
the red sandstone were known at that time, and geologists were not then
particular to distinguish between Amphibians and Reptiles.”
{119} This refers to Cuvier's discovery of Palæotherium &c. at Montmartre.
{120} This simile is more fully given in the Origin, Ed. i. p. 310, vi. p. 452. “For
my part, following out Lyell’s metaphor, I look at the natural geological record,
as a history of the world imperfectly kept, and written in a changing dialect; of
this history we possess the last volume alone, relating only to two or three
countries. Of this volume, only here and there a short chapter has been
preserved; and of each page, only here and there a few lines. Each word of the
slowly-changing language, in which the history is supposed to be written, being
more or less different in the interrupted succession of chapters, may represent
the apparently abruptly changed forms of life, entombed in our consecutive, but
widely separated formations.” Professor Judd has been good enough to point out
to me, that Darwin’s metaphor is founded on the comparison of geology to
history in Ch. i. of the Principles of Geology, Ed. i. 1830, vol. i. pp. 1-4.

Professor Judd has also called my attention to another passage,—Principles, Ed.
i. 1833, vol. iii. p. 33, when Lyell imagines an historian examining “two buried
cities at the foot of Vesuvius, immediately superimposed upon each other.” The
historian would discover that the inhabitants of the lower town were Greeks
while those of the upper one were Italians. But he would be wrong in supposing
that there had been a sudden change from the Greek to the Italian language in
Campania. I think it is clear that Darwin’s metaphor is partly taken from this
passage. See for instance (in the above passage from the Origin) such phrases as
“history ... written in a changing dialect”—“apparently abruptly changed forms
of life.” The passage within [ ] in the above paragraph:—“Lyell’s views as far as
they go &c.,” no doubt refers, as Professor Judd points out, to Lyell not going so
far as Darwin on the question of the imperfection of the geological record.
{121} On rarity and extinction see Origin, Ed. i. pp. 109, 319, vi. pp. 133, 461.
{122} In the Origin, Ed. i. p. 346, vi. p. 493, the author begins his discussion on
geographical distribution by minimising the effect of physical conditions. He
lays great stress on the effect of barriers, as in the present Essay.
{123} Note in the original, “Would it be more striking if we took animals, take
Rhinoceros, and study their habitats?”
{124} Note by Mr A. R. Wallace. “The want of similarity referred to, is, between
the mountains of Brazil and Guiana and those of the Andes. Also those of the
Indian peninsula as compared with the Himalayas. In both cases there is
continuous intervening land.
“The islands referred to were, no doubt, the Galapagos for dissimilarity from S.
America; our own Islands as compared with Europe, and perhaps Java, for
similarity with continental Asia.”
{125} The arguments against multiple centres of creation are given in the
Origin, Ed. i. p. 352, vi. p. 499.
{126} In the Origin, Ed. i. p. 366, vi. p. 516, the author does not give his views
on the distribution of alpine plants as original but refers to Edward Forbes’ work
(Geolog. Survey Memoirs, 1846). In his autobiography, Darwin refers to this. “I
was forestalled” he says, “in only one important point, which my vanity has
always made me regret.” (Life and Letters, i. p. 88.)
{127} «The following is written on the back of a page of the ms.» Discuss one or
more centres of creation: allude strongly to facilities of dispersal and amount of
geological change: allude to mountain-summits afterwards to be referred to. The
distribution varies, as everyone knows, according to adaptation, explain going
from N. to S. how we come to fresh groups of species in the same general
region, but besides this we find difference, according to greatness of barriers, in
greater proportion than can be well accounted for by adaptation. «On
representive species see Origin, Ed. i. p. 349, vi. p. 496.» This very striking
when we think of cattle of Pampas, plants «?» &c. &c. Then go into discussion;
this holds with 3 or 4 main divisions as well as the endless minor ones in each of
these 4 great ones: in these I chiefly refer to mammalia &c. &c. The similarity of
type, but not in species, in same continent has been much less insisted on than
the dissimilarity of different great regions generically: it is more striking.

«I have here omitted an incomprehensible sentence.» Galapagos Islands, Tristan
d’Acunha, volcanic islands covered with craters we know lately did not support
any organisms. How unlike these islands in nature to neighbouring lands. These
facts perhaps more striking than almost any others. [Geology apt to affect
geography therefore we ought to expect to find the above.] Geological-
geographical distribution. In looking to past times we find Australia equally
distinct. S. America was distinct, though with more forms in common. N.
America its nearest neighbour more in common,—in some respects more, in
some less allied to Europe. Europe we find «?» equally European. For Europe is
now part of Asia though not «illegible». Africa unknown,—examples, Elephant,
Rhinoceros, Hippopotamus, Hyaena. As geology destroys geography we cannot
be surprised in going far back we find Marsupials and Edentata in Europe: but
geology destroys geography.
{128} Rincon in Spanish means a nook or corner, it is here probably used to
mean a small farm.
{129} The following is written across the page: “No one would expect a set of
similar varieties to be produced in the different countries, so species different.”
{130} «The following passage seems to have been meant to follow here.» The
parent of an organism, we may generally suppose to be in less favourable
condition than the selected offspring and therefore generally in fewer numbers.
(This is not borne out by horticulture, mere hypothesis; as an organism in
favourable conditions might by selection be adapted to still more favourable
conditions.)
Barrier would further act in preventing species formed in one part migrating to
another part.
{131} «The following notes occur on the back of the page.» Number of species
not related to capabilities of the country: furthermore not always those best
adapted, perhaps explained by creationists by changes and progress. «See p. 34,
note 1.»
Although creationists can, by help of geology, explain much, how can he explain
the marked relation of past and present in same area, the varying relation in other
cases, between past and present, the relation of different parts of same great area.
If island, to adjoining continent, if quite different, on mountain summits,—the
number of individuals not being related to capabilities, or how &c.—our theory,
I believe, can throw much light and all facts accord.
{132} See Origin, Ed. i. p. 390, vi. p. 543.
{133} On oscillation see Origin, Ed. i. p. 291, vi. p. 426.
{134} «From the back of ms.» Effect of climate on stationary island and on
continent, but continent once island. Moreover repeated oscillations fresh
diffusion when non-united, then isolation, when rising again immigration
prevented, new habitats formed, new species, when united free immigration,
hence uniform characters. Hence more forms «on?» the island. Mountain
summits. Why not true species. First let us recall in Part I, conditions of
variation: change of conditions during several generations, and if frequently

altered so much better [perhaps excess of food]. Secondly, continued selection
[while in wild state]. Thirdly, isolation in all or nearly all,—as well to recall
advantages of.
[In continent, if we look to terrestrial animal, long continued change might go
on, which would only cause change in numerical number «? proportions»: if
continued long enough might ultimately affect all, though to most continents
«there is» chance of immigration. Some few of whole body of species must be
long affected and entire selection working same way. But here isolation absent,
without barrier, cut off such «illegible». We can see advantage of isolation. But
let us take case of island thrown up by volcanic agency at some distances, here
we should have occasional visitants, only in few numbers and exposed to new
conditions and «illegible» more important,—a quite new grouping of organic
beings, which would open out new sources of subsistence, or «would» control
«?» old ones. The number would be few, can old have the very best opportunity.
«The conquest of the indigenes by introduced organisms shows that the
indigenes were not perfectly adapted, see Origin, Ed. i. p. 390.» Moreover as the
island continued changing,—continued slow changes, river, marshes, lakes,
mountains &c. &c., new races as successively formed and a fresh occasional
visitant.
If island formed continent, some species would emerge and immigrate.
Everyone admits continents. We can see why Galapagos and C. Verde differ «see
Origin, Ed. i. p. 398»], depressed and raised. We can see from this repeated
action and the time required for a continent, why many more forms than in New
Zealand «see Origin, Ed. i. p. 389 for a comparison between New Zealand and
the Cape» no mammals or other classes «see however, Origin, Ed. i. p. 393 for
the case of the frog». We can at once see how it comes when there has been an
old channel of migration,—Cordilleras; we can see why Indian Asiatic Flora,—
[why species] having a wide range gives better chance of some arriving at new
points and being selected, and adapted to new ends. I need hardly remark no
necessity for change.
Finally, as continent (most extinction «?» during formation of continent) is
formed after repeated elevation and depression, and interchange of species we
might foretell much extinction, and that the survivor would belong to same type,
as the extinct, in same manner as different part of same continent, which were
once separated by space as they are by time «see Origin, Ed. i. pp. 339 and 349».
As all mammals have descended from one stock, we ought to expect that every
continent has been at some time connected, hence obliteration of present ranges.
I do not mean that the fossil mammifers found in S. America are the lineal
successors «ancestors» of the present forms of S. America: for it is highly
improbable that more than one or two cases (who will say how many races after
Plata bones) should be found. I believe this from numbers, who have lived,—
mere «?» chance of fewness. Moreover in every case from very existence of
genera and species only few at one time will leave progeny, under form of new
species, to distant ages; and the more distant the ages the fewer the progenitors.
An observation may be here appended, bad chance of preservation on rising
island, the nurseries of new species, appeal to experience «see Origin, Ed. i. p.
292». This observation may be extended, that in all cases, subsiding land must
be, in early stages, less favourable to formation of new species; but it will isolate

them, and then if land recommences rising how favourable. As preoccupation is
bar to diffusion to species, so would it be to a selected variety. But it would not
be if that variety was better fitted to some not fully occupied station; so during
elevation or the formation of new stations, is scene for new species. But during
elevation not favourable to preservation of fossil (except in caverns «?»); when
subsidence highly favourable in early stages to preservation of fossils; when
subsidence, less sediment. So that our strata, as general rule will be the tomb of
old species (not undergoing any change) when rising land the nursery. But if
there be vestige will generally be preserved to future ages, the new ones will not
be entombed till fresh subsidence supervenes. In this long gap we shall have no
record: so that wonderful if we should get transitional forms. I do not mean
every stage, for we cannot expect that, as before shown, until geologists will be
prepared to say that although under unnaturally favourable condition we can
trace in future ages short-horn and Herefordshire «see note 2, p. 26».
{135} After “organs” is inserted, apparently as an afterthought:—“no, and
instance metamorphosis, afterwards explicable.”
{136} For analogical resemblances see Origin, Ed. i. p. 427, vi. p. 582.
{137} “Practically when naturalists are at work, they do not trouble themselves
about the physiological value of the characters.... If they find a character nearly
uniform,... they use it as one of high value,” Origin, Ed. i. p. 417, vi. p. 573.
{138} “We are cautioned ... not to class two varieties of the pine-apple together,
merely because their fruit, though the most important part, happens to be nearly
identical,” Origin, Ed. i. p. 423, vi. p. 579.
{139} The whole of this passage is obscure, but the text is quite clear, except for
one illegible word.
{140} «The exact position of the following passage is uncertain:» “just as it is
not likely every present breed of fancy birds and cattle will propagate, only some
of the best.”
{141} This suggests that the author was not far from the principle of divergence
on which he afterwards laid so much stress. See Origin, Ed. i. p. 111, vi. p. 134,
also Life and Letters, i. p. 84.
{142} That is to say the same conditions occurring in different parts of the
globe.
{143} The position of the following is uncertain, “greyhound and racehorse have
an analogy to each other.” The same comparison occurs in the Origin, Ed. i. p.
427, vi. p. 583.
{144} Air is evidently intended; in the ms. water is written twice.
{145} Written between the lines occurs:—“extend to birds and other classes.”
{146} Written between the lines occurs:—“many bones merely represented.”
{147} In the Origin, Ed. i. p. 434, vi. p. 595, the term morphology is taken as
including unity of type. The paddle of the porpoise and the wing of the bat are
there used as instances of morphological resemblance.

{148} The sentence is difficult to decipher.
{149} In the Origin, Ed. i. p. 436, vi. p. 598, the author speaks of the “general
pattern” being obscured in the paddles of “extinct gigantic sea-lizards.”
{150} See Origin, Ed. i. p. 437, vi. p. 599.
{151} The following passage seems to have been meant to precede the sentence
beginning “These facts”:—“It is evident, that when in each individual species,
organs are metamorph. a unity of type extends.”
{152} This is, I believe, the first place in which the author uses the words
“theory of descent.”
{153} The sentence should probably run, “Let us take the case of the vertebrata:
if we assume them to be descended from one parent, then by this theory they
have been altered &c.”
{154} That is “we should call it a morphological fact.”
{155} In the Origin, Ed. i. p. 438, vi. p. 602, the author, referring to the
expressions used by naturalists in regard to morphology and metamorphosis,
says “On my view these terms may be used literally.”
{156} See Origin, Ed. i. p. 439, vi. p. 605.
{157} In the Origin, Ed. i. p. 440, vi. p. 606, the author argues that the “loop-
like course of the arteries” in the vertebrate embryo has no direct relation to the
conditions of existence.
{158} The following passages are written across the page:—“They pass through
the same phases, but some, generally called the higher groups, are further
metamorphosed.
? Degradation and complication? no tendency to perfection.
? Justly argued against Lamarck?”
{159} An almost identical passage occurs in the Origin, Ed. i. p. 440, vi. p. 606.
{160} The following: “Deaths of brothers «when» old by same peculiar disease”
which is written between the lines seems to have been a memorandum which is
expanded a few lines lower. I believe the case of the brothers came from Dr R.
W. Darwin.
{161} See the discussion to this effect in the Origin, Ed. i. pp. 443-4, vi. p. 610.
The author there makes the distinction between a cause affecting the germ-cell
and the reaction occurring at a late period of life.
{162} Possibly the sentence was meant to end “is not visible till then.”
{163} See Origin, Ed. i. pp. 444-5, vi. p. 611. The query appended to much less
is justified, since measurement was necessary to prove that the greyhound and
bulldog puppies had not nearly acquired “their full amount of proportional
difference.”

{164} «The following discussion, from the back of the page, is in large measure
the same as the text.» I think light can be thrown on these facts. From the
following peculiarities being hereditary, [we know that some change in the
germinal vesicle is effected, which will only betray itself years after] diseases—
man, goitre, gout, baldness, fatness, size, [longevity «illegible» time of
reproduction, shape of horns, case of old brothers dying of same disease]. And
we know that the germinal vesicle must have been affected, though no effect is
apparent or can be apparent till years afterwards,—no more apparent than when
these peculiarities appear by the exposure of the full-grown individual. «That is,
“the young individual is as apparently free from the hereditary changes which
will appear later, as the young is actually free from the changes produced by
exposure to certain conditions in adult life.”» So that when we see a variety in
cattle, even if the variety be due to act of reproduction, we cannot feel sure at
what period this change became apparent. It may have been effected during early
age of free life «or» fœtal existence, as monsters show. From arguments before
used, and crossing, we may generally suspect in germ; but I repeat it does not
follow, that the change should be apparent till life fully developed; any more
than fatness depending on heredity should be apparent during early childhood,
still less during fœtal existence. In case of horns of cattle, which when inherited
must depend on germinal vesicle, obviously no effect till cattle full-grown.
Practically it would appear that the [hereditary] peculiarities characterising our
domestic races, therefore resulting from vesicle, do not appear with their full
characters in very early states; thus though two breeds of cows have calves
different, they are not so different,—grey-hound and bull-dog. And this is what
is «to» be expected, for man is indifferent to characters of young animals and
hence would select those full-grown animals which possessed the desirable
characteristics. So that from mere chance we might expect that some of the
characters would be such only as became fully apparent in mature life.
Furthermore we may suspect it to be a law, that at whatever time a new character
appears, whether from vesicle, or effects of external conditions, it would appear
at corresponding time «see Origin, Ed. i. p. 444». Thus diseases appearing in old
age produce children with do.,—early maturity,—longevity,—old men, brothers,
of same disease—young children of do. I said men do not select for quality of
young,—calf with big bullocks. Silk-worms, peculiarities which, appear in
caterpillar state or cocoon state, are transmitted to corresponding states. The
effect of this would be that if some peculiarity was born in a young animal, but
never exercised, it might be inherited in young animal; but if exercised that part
of structure would be increased and would be inherited in corresponding time of
life after such training.
I have said that man selects in full-life, so would it be in Nature. In struggle of
existence, it matters nothing to a feline animal, whether kitten eminently feline,
as long as it sucks. Therefore natural selection would act equally well on
character which was fully «developed» only in full age. Selection could tend to
alter no character in fœtus, (except relation to mother) it would alter less in
young state (putting on one side larva condition) but alter every part in full-
grown condition. Look to a fœtus and its parent, and again after ages fœtus and
its «i. e. the above mentioned parents» descendant; the parent more variable «?»
than fœtus, which explains all.

{165} Some of these examples occur in Origin, Ed. i. pp. 450-51, vi. pp. 619-20.
{166} The two following sentences are written, one down the margin, the other
across the page. “Abortive organs eminently useful in classification. Embryonic
state of organs. Rudiments of organs.”
{167} I imagine the meaning to be that abortive organs are specific characters in
contrast to monstrosities.
{168} Minute hanging horns are mentioned in the Origin, Ed. i. p. 454, vi. p.
625, as occurring in hornless breeds of cattle.
{169} Linum flavum is dimorphic: thyme gynodiæcious. It is not clear what
point is referred to under Geranium pyrenaicum.
{170} The author’s work on duck’s wings &c. is in Var. under Dom., Ed. 2, i. p.
299.
{171} The words vis medicatrix are inserted after “useless,” apparently as a
memorandum.
{172} In the male florets of certain Compositæ the style functions merely as a
piston for forcing out the pollen.
{173} «On the back of the page is the following.» If abortive organs are a trace
preserved by hereditary tendency, of organ in ancestor of use, we can at once see
why important in natural classification, also why more plain in young animal
because, as in last section, the selection has altered the old animal most. I repeat,
these wondrous facts, of parts created for no use in past and present time, all can
by my theory receive simple explanation; or they receive none and we must be
content with some such empty metaphor, as that of De Candolle, who compares
creation to a well covered table, and says abortive organs may be compared to
the dishes (some should be empty) placed symmetrically!
{174} The author doubtless meant that the complex relationships between
organisms can be roughly represented by a net in which the knots stand for
species.
{175} Between the lines occurs:—“one «?» form be lost.”
{176} The original sentence is here broken up by the insertion of:—“out of the
dust of Java, Sumatra, these «?» allied to past and present age and «illegible»,
with the stamp of inutility in some of their organs and conversion in others.”
{177} Between the lines occur the words:—“Species vary according to same
general laws as varieties; they cross according to same laws.”
{178} “A cross with a bull-dog has affected for many generations the courage
and obstinacy of greyhounds,” Origin, Ed. i. p. 214, vi. p. 327.
{179} The simile of the savage and the ship occurs in the Origin, Ed. i. p. 485,
vi. p. 665.
{180} In the Origin, Ed. i. p. 486, vi. p. 665, the author speaks of the “summing
up of many contrivances”: I have therefore introduced the above words which

make the passage clearer. In the Origin the comparison is with “a great
mechanical invention,”—not with a work of art.
{181} See a similar passage in the Origin, Ed. i. p. 487, vi. p. 667.
{182} See the Origin, Ed. i. p. 488, vi. p. 668.
{183} The following discussion, together with some memoranda are on the last
page of the ms. “The supposed creative spirit does not create either number or
kind which «are» from analogy adapted to site (viz. New Zealand): it does not
keep them all permanently adapted to any country,—it works on spots or areas
of creation,—it is not persistent for great periods,—it creates forms of same
groups in same regions, with no physical similarity,—it creates, on islands or
mountain summits, species allied to the neighbouring ones, and not allied to
alpine nature as shown in other mountain summits—even different on different
island of similarly constituted archipelago, not created on two points: never
mammifers created on small isolated island; nor number of organisms adapted to
locality: its power seems influenced or related to the range of other species
wholly distinct of the same genus,—it does not equally effect, in amount of
difference, all the groups of the same class.”
{184} This passage is the ancestor of the concluding words in the first edition of
the Origin of Species which have remained substantially unchanged throughout
subsequent editions, “There is grandeur in this view of life, with its several
powers, having been originally breathed into a few forms or into one; and that
whilst this planet has gone cycling on according to the fixed law of gravity, from
so simple a beginning endless forms most beautiful and most wonderful have
been, and are being, evolved.” In the 2nd edition “by the Creator” is introduced
after “originally breathed.”
{185} Compare the Origin, Ed. i. p. 481, vi. p. 659, “The difficulty is the same
as that felt by so many geologists, when Lyell first insisted that long lines of
inland cliffs had been formed, and great valleys excavated, by the slow action of
the coast-waves.”
{186} The cumulative effect of domestication is insisted on in the Origin, see
e.g. Origin, Ed. i. p. 7, vi. p. 8.
{187} This type of variation passes into what he describes as the direct effect of
conditions. Since they are due to causes acting during the adult life of the
organism they might be called individual variations, but he uses this term for
congenital variations, e.g. the differences discoverable in plants raised from
seeds of the same pod (Origin, Ed. i. p. 45, vi. p. 53).
{188} «It is not clear where the following note is meant to come»: Case of
Orchis,—most remarkable as not long cultivated by seminal propagation. Case
of varieties which soon acquire, like Ægilops and Carrot (and Maize) a certain
general character and then go on varying.
{189} Here, as in the ms. of 1842, the author is inclined to minimise the
variation occurring in nature.
{190} This is more strongly stated than in the Origin, Ed. i. p. 30.