288 Colour and the Struggle for Infe 
appeared in the following year, and after reading it Darwin 
wrote as follows, Nov. 20, 1862: “...IN my opinion it is one 
of the most remarkable and admirable papers I ever read in my 
life......I[ am rejoiced that I passed over the whole subject in the 
Origin, for I should have made a precious mess of it. You have 
most clearly stated and solved a wonderful problem...... Your paper is 
too good to be largely appreciated by the mob of naturalists without 
souls ; but, rely on it, that it will have lasting value, and I cordially 
congratulate you on your first great work. You will find, I should 
think, that Wallace will fully appreciate it.” Four days later, 
Nov. 24, Darwin wrote to Hooker on the same subject: “I have 
now finished his paper...; it seems to me admirable. To my mind 
the act of segregation of varieties into species was never so plainly 
brought forward, and there are heaps of capital miscellaneous 
observations?.” 
Darwin was here referring to the tendency of similar varieties 
of the same species to pair together, and on Nov. 25 he wrote to 
Bates asking for fuller information on this subject®. If Bates’s 
opinion were well founded, sexual selection would bear a most im- 
portant part in the establishment of such species‘. It must be 
admitted, however, that the evidence is as yet quite insufficient to 
establish this conclusion. It is interesting to observe how Darwin at 
once fixed on the part of Bates’s memoir which seemed to bear upon 
sexual selection. A review of Bates’s theory of Mimicry was con- 
tributed by Darwin to the Natural History Review® and an account 
of it is to be found in the Origin® and in The Descent of Man’. 
Darwin continually writes of the value of hypothesis as the 
inspiration of inquiry. We find an example in his letter to Bates, 
Nov. 22, 1860: “I have an old belief that a good observer really 
means a good theorist, and I fully expect to find your observations 
most valuable®.” Darwin’s letter refers to many problems upon 
which Bates had theorised and observed, but as regards Mimicry itself 
the hypothesis was thought out after the return of the letter from the 
Amazons, when he no longer had the opportunity of testing it by the 
observation of living Nature. It is by no means improbable that, 
had he been able to apply this test, Bates would have recognised 
that his division of butterfly resemblances into two classes,—one due 
1 Life and Letters, 1. pp. 391—393. 
2 More Letters, 1. p. 214, 
3 More Letters, 1. p. 215. See also parts of Darwin’s letter to Bates in Life and 
Letters, u. p. 392. 
+ See Poulton, Essays on Evolution, 1908, pp. 65, 85—88, 
= New Ser. Vol. mm. 1863, p. 219, 6 Ed. 1872, pp. 375—378. 
? Ed. 1874, pp. 323—325. 8 More Letters, 1. p. 176, 
