At another place, speaking of intermediate forms he says:--
"Cuvier objects to propagation of species by saying, why have not some intermediate forms been discovered between Palaeotherium, Megalonyx, Mastodon, and the species now living? Now according to my view (in S. America) parent of all Armadilloes might be brother to Megatherium--uncle now dead."
Speaking elsewhere of intermediate forms, he remarks:--
"Opponents will say--"show them me." I will answer yes, if you will show me every step between bulldog and greyhound."
Here we see that the case of domestic animals was already present in his mind as bearing on the production of natural species. The disappearance of intermediate forms naturally leads up to the subject of extinction, with which the next extract begins.
"It is a wonderful fact, horse, elephant, and mastodon, dying out about same time in such different quarters.
"Will Mr. Lyell say that some [same?] circ.u.mstance killed it over a tract from Spain to South America?--(Never).
"They die, without they change, like golden pippins; it is a GENERATION OF SPECIES like generation OF INDIVIDUALS.
"Why does individual die? To perpetuate certain peculiarities (therefore adaptation), and obliterate accidental varieties, and to accommodate itself to change (for, of course, change, even in varieties, is accommodation). Now this argument applies to species.
"If individual cannot propagate he has no issue--so with species.
"If SPECIES generate other SPECIES, their race is not utterly cut off:-- like golden pippins, if produced by seed, go on--otherwise all die.
"The fossil horse generated, in South Africa, zebra--and continued--perished in America.
"All animals of same species are bound together just like buds of plants, which die at one time, though produced either sooner or later.
Prove animals like plants--trace gradation between a.s.sociated and non-a.s.sociated animals--and the story will be complete."
Here we have the view already alluded to of a term of life impressed on a species.
But in the following note we get extinction connected with unfavourable variation, and thus a hint is given of natural selection:
"With respect to extinction, we can easily see that [a] variety of [the]
ostrich (Petise), may not be well adapted, and thus perish out; or, on the other hand, like Orpheus [a Galapagos bird], being favourable, many might be produced. This requires [the] principle that the permanent variations produced by confined breeding and changing circ.u.mstances are continued and produced according to the adaptation of such circ.u.mstance, and therefore that death of species is a consequence (contrary to what would appear from America) of non-adaptation of circ.u.mstances."
The first part of the next extract has a similar bearing. The end of the pa.s.sage is of much interest, as showing that he had at this early date visions of the far-reaching character of the theory of evolution:--
"With belief of trans.m.u.tation and geographical grouping, we are lead to endeavour to discover CAUSES of change; the manner of adaptation (wish of parents??), instinct and structure becomes full of speculation and lines of observation. View of generation being condensation (I imagine him to mean that each generation is "condensed" to a small number of the best organized individuals.) test of highest organisation intelligible...My theory would give zest to recent and fossil comparative anatomy; it would lead to the study of instincts, heredity, and mind-heredity, whole [of] metaphysics.
"It would lead to closest examination of hybridity and generation, causes of change in order to know what we have come from and to what we tend--to what circ.u.mstances favour crossing and what prevents it--this, and direct examination of direct pa.s.sages of structure in species, might lead to laws of change, which would then be [the] main object of study, to guide our speculations."
The following two extracts have a similar interest; the second is especially interesting, as it contains the germ of concluding sentence of the "Origin of Species": ("Origin of Species" (1st edition), page 490:-- "There is a 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.")--
"Before the attraction of gravity discovered it might have been said it was as great a difficulty to account for the movement of all [planets]
by one law, as to account for each separate one; so to say that all mammalia were born from one stock, and since distributed by such means as we can recognise, may be thought to explain nothing.
"Astronomers might formerly have said that G.o.d fore-ordered each planet to move in its particular destiny. In the same manner G.o.d orders each animal created with certain forms in certain countries, but how much more simple and sublime [a] power--let attraction act according to certain law, such are inevitable consequences--let animals be created, then by the fixed laws of generation, such will be their successors.
"Let the powers of transportal be such, and so will be the forms of one country to another--let geological changes go at such a rate, so will be the number and distribution of the species!!"
The three next extracts are of miscellaneous interest:--
"When one sees nipple on man"s breast, one does not say some use, but s.e.x not having been determined--so with useless wings under elytra of beetles--born from beetles with wings, and modified--if simple creation merely, would have been born without them."
"In a decreasing population at any one moment fewer closely related (few species of genera); ultimately few genera (for otherwise the relationship would converge sooner), and lastly, perhaps, some one single one. Will not this account for the odd genera with few species which stand between great groups, which we are bound to consider the increasing ones?"
The last extract which I shall quote gives the germ of his theory of the relation between alpine plants in various parts of the world, in the publication of which he was forestalled by E. Forbes (see volume i.
page 72). He says, in the 1837 note-book, that alpine plants, "formerly descended lower, therefore [they are] species of lower genera altered, or northern plants."
When we turn to the Sketch of his theory, written in 1844 (still therefore before the second edition of the "Journal" was completed), we find an enormous advance made on the note-book of 1837. The Sketch is an fact a surprisingly complete presentation of the argument afterwards familiar to us in the "Origin of Species." There is some obscurity as to the date of the short Sketch which formed the basis of the 1844 Essay.
We know from his own words (volume i., page 68), that it was in June 1842 that he first wrote out a short sketch of his views. (This version I cannot find, and it was probably destroyed, like so much of his MS., after it had been enlarged and re-copied in 1844.) This statement is given with so much circ.u.mstance that it is almost impossible to suppose that it contains an error of date. It agrees also with the following extract from his 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 species theory."
Again in the introduction to the "Origin," page 1, he writes, "after an interval of five years" work" [from 1837, i.e. in 1842], "I allowed myself to speculate on the subject, and drew up some short notes."
Nevertheless in the letter signed by Sir C. Lyell and Sir J.D. Hooker, which serves as an introduction to the joint paper of Messrs. C. Darwin and A. Wallace on the "Tendency of Species to form Varieties," ("Linn.
Soc. Journal," 1858, page 45.) the essay of 1844 (extracts from which form part of the paper) is said to have been "sketched in 1839, and copied in 1844." This statement is obviously made on the authority of a note written in my father"s hand across the Table of Contents of the 1844 Essay. It is to the following effect: "This was sketched in 1839, and copied out in full, as here written and read by you in 1844." I conclude that this note was added in 1858, when the MS. was sent to Sir J.D. Hooker (see Letter of June 29, 1858, page 476). There is also some further evidence on this side of the question. Writing to Mr. Wallace (January 25, 1859) my father says:-- "Every one whom I have seen has thought your paper very well written and interesting. It puts my extracts (written in 1839, now just twenty years ago!), which I must say in apology were never for an instant intended for publication; into the shade." The statement that the earliest sketch was written in 1839 has been frequently made in biographical notices of my father, no doubt on the authority of the "Linnean Journal," but it must, I think, be considered as erroneous. The error may possibly have arisen in this way.
In writing on the Table of Contents of the 1844 MS. that it was sketched in 1839, I think my father may have intended to imply that the framework of the theory was clearly thought out by him at that date. In the Autobiography he speaks of the time, "about 1839, when the theory was clearly conceived," meaning, no doubt, the end of 1838 and beginning of 1839, when the reading of Malthus had given him the key to the idea of natural selection. But this explanation does not apply to the letter to Mr. Wallace; and with regard to the pa.s.sage (My father certainly saw the proofs of the paper, for he added a foot-note apologising for the style of the extracts, on the ground that the "work was never intended for publication.") in the "Linnean Journal" it is difficult to understand how it should have been allowed to remain as it now stands, conveying, as it clearly does, the impression that 1839 was the date of his earliest written sketch.
The sketch of 1844 is written in a clerk"s hand, in two hundred and thirty-one pages folio, blank leaves being alternated with the MS.
with a view to amplification. The text has been revised and corrected, criticisms being pencilled by himself on the margin. It is divided into two parts: I. "On the variation of Organic Beings under Domestication and in their Natural State." II. "On the Evidence favourable and opposed to the view that Species are naturally formed races descended from common Stocks." The first part contains the main argument of the "Origin of Species." It is founded, as is the argument of that work, on the study of domestic animals, and both the Sketch and the "Origin" open with a chapter on variation under domestication and on artificial selection. This is followed, in both essays, by discussions on variation under nature, on natural selection, and on the struggle for life. Here, any close resemblance between the two essays with regard to arrangement ceases. Chapter III. of the Sketch, which concludes the first part, treats of the variations which occur in the instincts and habits of animals, and thus corresponds to some extent with Chapter VII. of the "Origin" (1st edition). It thus forms a complement to the chapters which deal with variation in structure. It seems to have been placed thus early in the Essay to prevent the hasty rejection of the whole theory by a reader to whom the idea of natural selection acting on instincts might seem impossible. This is the more probable, as the Chapter on Instinct in the "Origin" is specially mentioned (Introduction, page 5) as one of the "most apparent and gravest difficulties on the theory." Moreover the chapter in the Sketch ends with a discussion, "whether any particular corporeal structures...are so wonderful as to justify the rejection prima facie of our theory." Under this heading comes the discussion of the eye, which in the "Origin" finds its place in Chapter VI. under "Difficulties of the Theory." The second part seems to have been planned in accordance with his favourite point of view with regard to his theory. This is briefly given in a letter to Dr. Asa Gray, November 11th, 1859: "I cannot possibly believe that a false theory would explain so many cla.s.ses of facts, as I think it certainly does explain. On these grounds I drop my anchor, and believe that the difficulties will slowly disappear." On this principle, having stated the theory in the first part, he proceeds to show to what extent various wide series of facts can be explained by its means.
Thus the second part of the Sketch corresponds roughly to the nine concluding Chapters of the First Edition of the "Origin." But we must exclude Chapter VII. ("Origin") on Instinct, which forms a chapter in the first part of the Sketch, and Chapter VIII. ("Origin") on Hybridism, a subject treated in the Sketch with "Variation under Nature" in the first part.
The following list of the chapters of the second part of the Sketch will ill.u.s.trate their correspondence with the final chapters of the "Origin."
Chapter I. "On the kind of intermediateness necessary, and the number of such intermediate forms." This includes a geological discussion, and corresponds to parts of Chapters VI. and IX. of the "Origin."
Chapter II. "The gradual appearance and disappearance of organic beings." Corresponds to Chapter X. of the "Origin."
Chapter III. "Geographical Distribution." Corresponds to Chapters XI.
and XII. of the "Origin."
Chapter IV. "Affinities and Cla.s.sification of Organic beings."
Chapter V. "Unity of Type," Morphology, Embryology.
Chapter VI. Rudimentary Organs.
These three chapters correspond to Chapter XII. of the "Origin."
Chapter VII. Recapitulation and Conclusion. The final sentence of the Sketch, which we saw in its first rough form in the Note Book of 1837, closely resembles the final sentence of the "Origin," much of it being identical. The "Origin" is not divided into two "Parts," but we see traces of such a division having been present in the writer"s mind, in this resemblance between the second part of the Sketch and the final chapters of the "Origin." That he should speak ("Origin," Introduction, page 5.) of the chapters on transition, on instinct, on hybridism, and on the geological record, as forming a group, may be due to the division of his early MS. into two parts.
Mr. Huxley, who was good enough to read the Sketch at my request, while remarking that the "main lines of argument," and the ill.u.s.trations employed are the same, points out that in the 1844 Essay, "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.""
It is extremely interesting to find in the Sketch the first mention of principles familiar to us in the "Origin of Species." Foremost among these may be mentioned the principle of s.e.xual Selection, which is clearly enunciated. The important form of selection known as "unconscious," is also given. Here also occurs a statement of the law that peculiarities tend to appear in the offspring at an age corresponding to that at which they occurred in the parent.