

18 MY LIFE 



I 'ut here my view really extends the influence of natural 

 selection, because I show in how many unsuspected ways 

 colour and marking is of use to its possessor. I first stated 

 my objections to " female choice " in my review of the 

 "Descent of Man' (1871), and more fully developed it in 

 my "Tropical Nature" (1878), while in my "Darwinism' 

 (1889), I again discussed the whole subject, giving the results 

 of more mature consideration. I had, however, already dis- 

 cussed the matter at some length with Darwin, and in a letter 

 of September 18, 1869, I gave him my general argument as 

 follows : — 



I have a general and a special argument to submit. 

 1. Female birds and insects are usually exposed to more 

 danger than the male, and in the case of insects their existence 

 is necessary for a longer period. They therefore require, in 

 some way or other, an increased amount of protection. 



u 2. If the male and female were distinct species, with 

 different habits and organizations, you would, I think, admit 

 that a difference of colour, serving to make that one less 

 conspicuous which evidently required more protection than 

 the other, had been acquired by natural selection. 



" 3. But you admit that variations appearing in one sex 

 are (sometimes) transmitted to that sex only. There is there- 

 fore nothing to prevent natural selection acting on the two 

 sexes as if they were two species. 



"4. Your objection that the same protection would, to a 

 certain extent, be useful to the male seems to me quite unsound, 

 and directly opposed to your own doctrine so convincingly 

 urged in the " Origin," that natural selection never improves 

 an animal beyond its needs. Admitting, therefore, abundant 

 variation of colour in both sexes, it is impossible that the male 

 can be brought by natural selection to resemble the female 

 (unless such variations are always transmitted), because the 

 difference in their colours is for the purpose of making up for 

 their different organization and habits, and natural selection 

 cannot give to the male more protection than he requires, 

 which is less than in the female. 



" 5. The striking fact that in all protected groups the females 



