188 SEXUAL SELECTION: BIRDS. [Part II. 



have been able to survive, but would have been favored in 

 their rivalry with other males. Now, variations occurring 

 late in life tend to be transmitted exclusively to the same 

 sex, so that in this case extremely bright tints would not 

 have been transmitted to the females. On the other hand, 

 ornaments of a less conspicuous kind, such as those pos- 

 sessed by the Eared and Cheer pheasants, would not have 

 been dangerous, and, if they appeared during early youth, 

 would generally have been transmitted to both sexes. 



In addition to the effects of the partial transference of 

 characters from the males to the females, some of the dif- 

 ferences between the females of closely-allied species may 

 be attributed to the direct or definite action of the condi- 

 tions of life. 11 With the males any such action would 

 generally have been masked by the brilliant colors gained 

 through sexual selection ; but, not so with the females. 

 Each of the endless diversities in plumage, which we see 

 in our domesticated birds, is, of course, the result of some 

 definite cause ; and, under natural and more uniform con- 

 ditions, some one tint, assuming that it was in no way in- 

 jurious, would almost certainly sooner or later prevail 

 The free intercrossing of many individuals belonging t<? 

 the same species would ultimately tend to make any 

 change of color, thus induced, uniform in character. 



No one doubts that both sexes of many birds have had 

 their colors adapted for the sake of protection ; and it is 

 possible that the females alone of some species may have 

 been thus modified. Although it would be a difficult, per- 

 haps an impossible process, as shown in the last chapter, 

 to convert through selection one form of transmission into 

 another, there would not be the least difficulty in adapting 

 the colors of the female, independently of those of the 

 male, to surrounding objects, through the accumulation 



11 See, on this subject, chap, xxiii. in the ' Variation of Animals and 

 Plants under Domestication.' 



