SEXUAL SELECTION 569 



We have now seen that a perfect series can be followed, 

 from simple spots to the wonderful ball-and-socket orna- 

 ments. Mr. Gould, who kindly gave me some of these 

 feathers, fully agrees with me in the completeness of the 

 gradation. It is obvious that the stages in development 

 exhibited by the feathers on the same bird do not at all 

 necessarily show us the steps passed through by the extinct 

 progenitors of the species; but they probably give us the 

 clew to the actual steps, and they at least prove to demon- 

 stration that a gradation is possible. Bearing in mind how 

 carefully the male Argus pheasant displays his plumes 

 before the female, as well as the many facts rendering it 

 probable that female birds prefer the more attractive males, 

 no one who admits the agency of sexual selection in any 

 case will deny that a simple dark spot with some fulvous 

 shading might be converted, through the approximation and 

 modification of two adjoining spots, together with some 

 slight increase o.f color, into one of the so-called elliptic 

 ornaments. These latter ornaments have been shown to 

 many persons, and all have admitted that they are beauti- 

 ful, some thinking them even more so than the ball-and- 

 socket ocelli. As the secondary plumes became lengthened 

 through sexual selection, and as the elliptic ornaments in* 

 creased in diameter, their colors apparently became less 

 bright; and then the ornamentation of the plumes had to 

 be gained by an improvement in the pattern and shading ; 

 and this process was carried on until the wouderful ball- 

 and-socket ocelli were finally developed. Thus we can 

 understand — and in no other way as it seems to me — the 

 present condition and origin of the ornaments on the wing- 

 feathers of the Argus pheasant. 



From the light afforded by the principle of gradation — 

 from what we know of the .laws of variation — from the 

 changes which have taken place in many of our domesti- 

 cated birds — and, lastly, from the character (as we shall 

 hereafter see more clearly) of the immature plumage of 

 young birds — ^we can sometimes indicate, with a certain 



