The Evidence from Sexual Cliaracters. 209 



rendered her more conspicuous would often lead to her 

 destruction, and that of her offspring. All variations 

 in this direction in the female would therefore/sooner or 

 later, be eliminated, while such modifications as ren- 

 dered her inconspicuous by assimilating her to sur- 

 rounding objects, as the earth or the foliage, would, on 

 the whole, survive the longest, and thus lead to the at- 

 tainment of those brown or green and inconspicuous 

 tints which form the coloring (of the upper surface at 

 least) of the vast majority of female birds which sit 

 upon open nests." As a proof that this is the true ex- 

 planation of the dull plumage and lack of ornaments in 

 so many female birds, he states that wherever the nest 

 is domed or covered, or so placed as to conceal the sitting 

 bird, the plumage is strikingly gay and conspicuously 

 colored in both sexes; but that in those species where 

 there is a strong contrast in colors, and the male is gay 

 and conspicuous, while the female is dull and obscure, 

 the nest is open, and the sitting bird is exposed to view. 



Reasons for Holding that this Explanation is In- 

 adequate. 



The argument of Wallace, which is fully stated in the 

 essay above quoted, is briefly, that the dull plumage of 

 so many female birds, as contrasted with the gay colors 

 of the males, has been directly acquired in the females 

 by the destruction of the most conspicuous ones, and 

 the natural selection of the'inconspicuous varieties. 



Darwin has discussed it at length in his essay on 

 sexual selection, and has given many reasons for refus- 

 ing to give it unqualified acceptance, but I will give here 

 a few additional reasons for believing that the phenom- 

 ena in question depend upon some more fundamental 

 law* In the first place, we must bear in mind that, 



