242 THE STORY OF THE BIRDS 



or an outward manifestation of conjugal pas- 

 sion. There can be little doubt that the display 

 of so much excessive or supplementary vitality, 

 in the form of dimorphic secondary sexual char- 

 acters, has an overpowering effect upon the 

 female, quite irrespective of any conscious choice 

 or selection on her part ; and that, so overcome, 

 she yields to the embrace of the strongest and 

 most energetic male that, in spite of rival claims, 

 can take and keep her. 



