104 THE VALUE OF COLOUK 



these two naturalists, but it is clear that Darwin, 

 although fully believing in the efficiency of 

 Protective Eesemblance and replying to St. George 

 Mivart's contention that Natural Selection was 

 incompetent to produce it,^ never entirely agreed 

 with Wallace's estimate of its importance. Thus 

 the following extract from a letter to Sir Joseph 

 Hooker, May 21, 1868, refers to WaUace : ' I find 

 I must (and I always distrust myself when I 

 differ from him) separate rather widely from 

 him all about birds' nests and protection ; he is 

 riding that hobby to death.' ^ It is clear from 

 the account given in The Descent of Man,^ that 

 the divergence was due to the fact that Darwin 

 ascribed more importance to Sexual Selection 

 than did Wallace, and Wallace more importance 

 to Protective Resemblance than Darwin. Thus 

 Darwin wrote to Wallace, Oct. 12 and 13, 1867 : 

 ' By the way, I cannot but think that you push 

 protection too far in some cases, as with the 

 stripes on the tiger.'* Here too Darwin was 

 preferring the explanation offered by Sexual 

 Selection,^ a preference which, considering the 

 relation of the colouring of the lion and tiger to 

 their respective environments, few naturalists 

 will be found to share. It is also shown on 



1 Origin, (6tli edit.), London, 1872, 181, 182. See also 66. 

 ' More Letters, i. 304. 



" London, 1874, 452-8. See also Life and Letters, iii. 123-5, and 

 More Letters, ii. 59-68, 72-4, 76-8, 84-90, 92, 93. 

 * More Letters, i. 288. 

 = Descent of Man (2nd edit.), 1874, 545, 546. 



