88 MAN [Chap. VIII 



Letter 450 selection and never have been modified to bring the female 

 into harmony with the environment. " Sexual selection is 

 less rigorous than Natural Selection," and will therefore be 

 subordinate to it. 



I think the case of female Pieris pyrrJta proves that 

 females alone can be greatly modified for protection. 1 



Letter 451 A. R. Wallace to C. Darwin. 



On October 4th, 1868, Mr. Wallace wrote again on the same 

 subject without adding anything of importance to his arguments of 

 September 27th. We give his final remarks : — 



October 4th, 1868. 



I am sorry to find that our difference of opinion on this 

 point is a source of anxiety to you. Pray do not let it 

 be so. The truth will come out at last, and our difference 

 may be the means of setting others to work who may set 

 us both right. After all, this question is only an episode 

 (though an important one) in the great question of the 

 " Origin of Species," and whether you or I are right will 

 not at all affect the main doctrine — that is one comfort. 



I hope you will publish your treatise on " Sexual 

 Selection " as a separate book as soon as possible ; and then, 

 while you are going on with your other work, there will 

 no doubt be found some one to battle with me over your 

 facts on this hard problem. 



Letter 452 To A. R. Wallace. 



Down, October 6th [1868]. 

 Your letter is very valuable to me, and in every way very 

 kind. I will not inflict a long answer, but only answer your 

 queries. There are breeds (viz. Hamburg) in which both 

 sexes differ much from each other and from both sexes of 

 Gallus bankiva ; and both sexes are kept constant by 

 selection. The comb of the Spanish male has been ordered 

 to be upright, and that of Spanish female to lop over, and 

 this has been effected. There are sub-breeds of game fowl, 

 with females very distinct and males almost identical ; but 

 this, apparently, is the result of spontaneous variation, without 



1 My latest views on this subject, with many new facts and argu- 

 ments, will be found in the later editions of my Darwinism, Chap. X. 

 (A. R. W.) 



