Alfred Russel Wallace 



do not know whether you admit that^ for instance, the spur 

 of the cock is due to sexual selection. 



I am quite willing to admit that the sounds and vocal 

 organs of some males are used only for challenging, 

 but I doubt whether this applies to the musical notes 

 of Hylobates or to the howling (I judge chiefly from 

 Eengger) of the American monkeys. No account that I 

 have seen of the stridulation of male insects shows that 

 it is a challenge. All those who have attended to birds 

 consider their song as a charm to the females and not as a 

 challenge. As the males in most cases search for the 

 females I do not see how their odoriferous organs will 

 aid them in finding the females. But it is foolish in me 

 to go on writing, for I believe I have said most of this in 

 my book : anyhow, I well remember thinking over it. The 

 ** belling '* of male stags, if I remember rightly, is a chal- 

 lenge, and so I daresay is the roaring of the lion during the 

 breeding season. 



I will just add in reference to your former letter that 

 I fully admit that with birds the fighting of the males 

 co-operates with their charms; and I remember quoting 

 Bartlett that gaudy colouring in the males is almost invari- 

 ably concomitant with pugnacity. But, thank Heaven, what 

 little more I can do in science will be confined to observa- 

 tion on simple points. However much I may have blun- 

 dered, I have done my best, and that is my constant comfort. 

 --Most truly yours, C. Darwin. 



WaMron Edge, Duppas Hill, Croydon. September 14, 1878. 



Dear Darwin, — An appointment is soon to be made of 

 someone to have the superintendence of Epping Forest 

 under the new Act, and as it is a post which of all others 

 I should like I am trying very hard to get up interest 

 enough to secure it. 



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