Chap. XVI. THE YOUNG LIKE THE ADULT FEMALES. 197 



action would generally have been masked by the 

 brilliant colours gained through sexual selection; but 

 not so with the females. Each of the endless diver- 

 sities in plumage, which we see in our domesticated 

 birds is, of course, the result of some definite cause ; 

 and under natural and more uniform conditions, some 

 one tint, assuming that it was in no way injurious, would 

 almost certainly sooner or later prevail. The free 

 intercrossing of the many individuals belonging to the 

 same species would ultimately tend to make any change 

 of colour, thus induced, uniform in character. 



No one doubts that both sexes of many birds have 

 had their colours adapted for the sake of protection ; 

 and it is possible that the females alone of some species 

 mav have been thus modified. Althouoh it would be a 

 difficult, perhaps an impossible process, as shewn in the 

 last chapter, to convert through selection one form of 

 transmission into another, there would not be the least 

 difficulty in adapting the colours of the female, inde- 

 pendently of those of the male, to surrounding objects, 

 through the accumulation of variations which were from 

 the first limited in their transmission to the female sex. 

 If the variations were not thus limited, the bright tints of 

 the male would be deteriorated or destroyed. Whether 

 the females alone of many species have been thus 

 specially modified, is at present very doubtful. I wish 

 I could follow Mr. Wallace to the full extent ; for the 

 admission would remove some difficulties. Any varia- 

 tions which were of no service to the female as a protec- 

 tion would be at once obliterated, instead of being lost 

 simply by not being selected, or from free intercrossing, 

 or from being eliminated when transferred to the male 

 and in any way injurious to him. Thus the plumage of 

 the female would be kept constant in character. It 

 would also be a relief if we could admit that the obscure 



