XIV 



implies the competition of varieties and the selection of those which 

 are relatively best adapted to the conditions. 



Neither Erasmus Darwin, nor Lamarck, had any inkling of the 

 possibility of this process of " natural selection " ; and though it had 

 been foreshadowed by Wells in 1813, and more fully stated by 

 Matthew in 1831, the speculations of the latter writer remained 

 unknown to naturalists until after the publication of the * Origin of 

 Species.' 



Darwin found in the doctrine of the selection of favourable varia- 

 tions by natural causes, which thus presented itself to his mind, not 

 merely a probable theory of the origin of the diverse species of living 

 forms, but that explanation of the phenomena of adaptation, which 

 previous speculations had utterly failed to give. The process of 

 natural selection is, in fact, dependent on adaptation — it is all one, 

 whether one says that the competitor which survives is the "fittest " 

 or the "best adapted. ' r And it was a perfectly fair deduction that 

 even the most complicated adaptations might result from the sum- 

 mation of a long series of simple favourable variations. 



Darwin notes as a serious defect in the first sketch of his theory 

 that he had omitted to consider one very important problem, the 

 solution of which did not occur to him till some time afterwards. 

 " This problem is the tendency in organic beings descended from the 



same stock to diverge in character as they become modified 



The solution, as I believe, is that the modified offspring of all domi- 

 nant and increasing forms tend to become adapted to many and highly 

 diversified places in the economy of nature/' (I, p. 84.) 



It is curious that so much importance should be attached to this 

 supplementary idea. It seems obvious that the theory of the origin of 

 species by natural selection necessarily involves the divergence of 

 the forms selected. An individual which varies, ipso facto diverges 

 from the type of its species ; and its progeny, in which the variation 

 becomes intensified by selection, must diverge still more, not only from 

 the parent stock, but from any other race of that stock starting 

 from a variation of a different character. The selective process 

 could not take place unless the selected variety was either better 

 adapted to the conditions than the original stock, or adapted to other 

 conditions than the original stock. In the first case, the original stock 

 would be sooner or later extirpated ; in the second, the type, as repre- 

 sented by the original stock and the variety,, would occupy more 

 diversified stations than it did before.. 



The theory, essentially such as it was published fourteen years 

 later, was written out in 1844, and Darwin was so fully convinced of 

 the importance of his work, as it then stood, that he made special 

 arrangements for its publication in case of his death. But it is a 

 singular example of reticent fortitude, that, although for the next 



