50 GENERAL PRINCIPLES OF ZOOLOGY, 



excellences. With strong wings and with spurs the cock main- 

 tains possession of his flock, the stag by means of his antlers, the 

 bull with his horns. The birds of paradise by means of beautiful 

 coloring win the favor of the females, most singing-birds by means 

 of song; many species of the fowl by peculiar love-dances. Since 



FIG. ISA. Paradisea apoda, male. (After Levaillant.) 



all these characters belong chiefly to the male, and since it is 

 only exceptionally that they are inherited by the female (and even 

 then are less pronounced), it is almost certain that in a great 

 measure they have been acquired by the males through the struggle 

 for the female. In the case of birds a second factor has un- 

 doubtedly co-operated to impress distinctly the often enormous 

 difference between the feathers of the male and of the female as 



