The Wallace-Darwin Correspondence 



sex (generally the male) and being transmitted exclusively, 

 or more commonly only in excess, to that sex. I, on the 

 other hand, formerly paid far too little attention to pro- 

 tection. I had only a glimpse of the truth. But even 

 now I do not go quite as far as you. I cannot avoid 

 thinking rather more than you do about the exceptions in 

 nesting to the rule, especially the partial exceptions, i.e. 

 when there is some little difference between the sexes in 

 species which build concealed nests. I am now quite satis- 

 fied about the incubating males; there is so little differ- 

 ence in conspicuousness between the sexes. I wish with 

 all my heart I could go the whole length with you. You 

 seem to think that such birds probably select the most 

 beautiful females : I must feel some doubt on this head, 

 for I can find no evidence of it. Though I am writing so 

 carping a note, I admire the article thoroughly. 



And now I want to ask a question. When female 

 butterflies are more brilliant than their males, you believe 

 that they have in most cases, or in all cases, been rendered 

 brilliant so as to mimic some other species and thus escape 

 danger. But can you account for the males not having been 

 rendered equally brilliant and equally protected ? Although 

 it may be most for the welfare of the species that the female 

 should be protected, yet it would be some advantage, cer- 

 tainly no disadvantage, for the unfortunate male to enjoy 

 an equal immunity from danger. For my part, I should 

 say that the female alone had happened to vary in the right 

 manner, and that the beneficial variations had been trans- 

 mitted to the same sex alone. Believing in this, I can see 

 no improbability (but from analogy of domestic animals a 

 strong probability) : the variations leading to beauty must 

 often have occurred in the males alone, and been trans- 

 mitted to that sex alone. Thus I should account in many 

 cases for the greater beauty of the male over the female, 



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