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 circumstance 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 passage (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.