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THE FOUNDATIONS OF THE ORIGIN OF SPECIES

CAMBRIDGE UNIVERSITY PRESS

London: FETTER LANE, E.C.

C. F. CLAY, MANAGER

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Edinburgh: 100, PRINCES STREET

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{Illustration: Charles Darwin 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

Sec. i. On variation under domestication, and on the principles of selection 1

Sec. ii. On variation in a state of nature and on the natural means of selection 4

Sec. iii. On variation in instincts and other mental attributes 17

PART II

Sec.Sec. iv. and v. On the evidence from Geology. (The reasons for combining the two sections are given in the Introduction) 22

Sec. vi. Geographical distribution 29

Sec. vii. Affinities and classification 35

Sec. viii. Unity of type in the great classes 38

Sec. ix. Abortive organs 45

Sec. x. Recapitulation and conclusion 48

ESSAY OF 1844

PART I

CHAPTER I 57-80

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

CHAPTER II 81-111

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

CHAPTER III 112-132

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

PART II

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

CHAPTER IV 133-143

ON THE NUMBER OF INTERMEDIATE FORMS REQUIRED ON THE THEORY OF COMMON DESCENT; AND ON THEIR ABSENCE IN A FOSSIL STATE

CHAPTER V 144-150

GRADUAL APPEARANCE AND DISAPPEARANCE OF SPECIES.

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 198-213

ON THE NATURE OF THE AFFINITIES AND CLASSIFICATION OF ORGANIC BEINGS.

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 214-230

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

CHAPTER IX 231-238

ABORTIVE OR RUDIMENTARY ORGANS.

The abortive organs of Naturalists The abortive organs of Physiologists Abortion from gradual disuse

CHAPTER X 239-255

RECAPITULATION AND CONCLUSION.

Recapitulation Why do we wish to reject the Theory of Common Descent? Conclusion

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?

{1} See the extracts in Life and Letters of Charles Darwin, ii. p. 5.

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."

{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.

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."

{5} Life and Letters, i. p. 82.

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.

{6} Obituary Notice, loc. cit.

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."

{7} Darwin and Modern Science.

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.

{8} Huxley, Obituary, p. xi.

{9} In this citation the italics are mine.

{10} Journal of Researches, Ed. 1860, p. 394.

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.

{11} F. Darwin's Life of Charles Darwin (in one volume), 1892, p. 166.

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."

{12} Life and Letters, i. p. 83.

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 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."

{13} Life and Letters, ii. p. 8.

{14} Avestruz Petise, i.e. Rhea Darwini.

{15} A bird.

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.

{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.

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,—foetal state,—abortive organs."

{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.

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.

{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.

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 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.

{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.

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.

{24} Life and Letters, i. p. 153.

When a word cannot be deciphered, it is replaced by:—, 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 .

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 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 Sec. VIII.; and Sec. 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 Sec.Sec. 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 Sec.Sec. 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 Sec. 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 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."

{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.

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.

{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.

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.

{30} Life and Letters, i. p. 84.

{31} Life and Letters, ii. p. 18.

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 L400 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 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 L400 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.

{32} Mrs Darwin's brother.

"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 L500.

{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."

"My remaining collections in Natural History may be given to any one or any museum where 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."

{34} The words "several years ago, and" seem to have been added at a later date.

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.

{35} Life and Letters, ii. p. 9.

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.

Sec. 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.

{36} Evidently a memorandum that an example should be given.

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 (Mueller's twins){38} seems inevitable effect of process of reproduction. But more important is that simple generation, especially under new conditions [when no crossing] 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.

{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 Mueller 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.

[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}.

{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 but differences besides the . 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.

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 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 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 form lives, but those most useful to him. This might all be otherwise.

{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.

Sec. 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.

{47} i.e. they are individually distinguishable.

{48} See Origin, Ed. i. p. 133, vi. p. 165.

Our experience would lead us to expect that any and every one of these organisms would vary if 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 how far the slowness would produce tendency to vary. But Geolog 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.

{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.

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 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, miseltoe, <sentence incomplete>. But if every part of a plant or animal was to vary , 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 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 rotten trees or [gradually select plants which 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.

{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."

Before considering whether 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 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 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 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 oeconomy of nature. This requires much reflection; study Malthus and calculate rates of increase and remember the resistance,—only periodical.

{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.

The unavoidable effect of this 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, 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.

{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.

Let hares{61} increase very slowly from change of climate affecting peculiar plants, and some other 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.

{61} This is a repetition of what is given at p. 6.

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 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}.

{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."

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 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 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, instincts best developed, will rear more young, probably possessing her good qualities, and a greater number will thus 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}.

{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.

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 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 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 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 effect on their mind and a special case.

{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 Gaertner 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.

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,—Linnaeus 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 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.

{73} Lindley's remark is quoted in the Origin, Ed. i. p. 9. Linnaeus' 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.

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 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 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 has been 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}.

{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."

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 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}.

{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.

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 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 vertebrae,—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}.

{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.

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.

Sec. 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 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 d^o. and d^o. Habits, as pointing and setting on certain occasions d^o. 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.

{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.

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, d^o. 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.

{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.

Every instinct must, by my theory, have been acquired gradually by slight changes 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.

{97} The meaning is that the attitude assumed in shamming is not accurately like that of death.

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 , 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.

{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.

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.

{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.

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.

{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.

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 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 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 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, that it is impossible to say we know the limit of races, which would be true 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 species been thus produced, this is a question wholly independent of all previous points, and which on examination of the kingdom of nature ought to answer one way or another.

{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).



PART II{104}.

{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 Sec. IV. ends and Sec. V. begins.

Sec.Sec. 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 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 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.

{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.

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 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, 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 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 Ornithorhyncus?). As far as geological discoveries they tend towards such gradation{110}. Illustrate it with net. Toxodon,—tibia and fibula,—dog and otter,—but so utterly improbable is , 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.]

{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, {Note 161} of this Essay.

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, littoral deposits: for otherwise denudation ,—they must live in a shallow space which sediment will tend to fill up,—as movement is 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}.

{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!"

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