The Evidence from Sexual Characters. 221 



veloped in the males, and that the males of allied breeds 

 differ from each other more than the females. 



The individuals of choice breeds of domestic pigeons 

 are not allowed to follow their own inclinations and to 

 pair at will, but they are very carefully watched by the 

 breeder, for reasons which have no reference to the in- 

 clinations of the birds, so that there is no chance for 

 sexual selection, nor does the breeder confine his atten- 

 tion to the male sex especially, but seeks to improve the 

 female as well as the male ; and Mr. Eaton asserts in his 

 "Treatise on the Almond Tumbler" that a hen tumbler 

 would be worth twice as much money as a cock if she 

 had the characteristics of the breed equally well de- 

 veloped. 



We find, then, that among the two hundred or more 

 wild species of the pigeon family, where sexual selection 

 has every chance to act, there is no great difference be- 

 tween the sexes ; but that in the more valuable domes- 

 ticated breeds, where all choice is precluded, and sexual 

 selection out of the question, the males are, as a rule, 

 more modified than the females whenever the sexes differ. 

 We must therefore conclude that the greater modification 

 of the males, in pigeons at least, is not due to the fact that 

 the male is more exposed than the female to the action 

 of selection, but that the male has more tendency than 

 the female to depart from the ancestral type. In pig- 

 eons, at least, we must believe that something within the 

 animal determines that the male should lead and the 

 female follow, in the evolution of new breeds. 



Domesticated Animals in General. 



When we study other domesticated animals in the 

 same way, we find that in some cases, as in horses, there 

 is little difference between the sexes, and in other cases 



