SEXUAL SELECTION. 



CHAPTER VIII. 



PRINCIPLES OF SEXUAL SELECTION. 



Secondary Sexual Characters. — Sexual Selection. — Manner of Action. — 

 Excess of Males. — Polygamy. — The Male alone generally modified 

 through Sexual Selection. — Eagerness of the Male. — Variability of 

 the Male. — Choice exerted by the Female. — Sexual compared with 

 Natural Selection. — Inheritance, at Corresponding Periods of Life, at 

 Corresponding Seasons of the Year, and as limited by Sex. — Eelations 

 between the Several Forms of Inheritance.' — Causes why one Sex and 

 the Young are not modified through Sexual Selection. — Supplement on 

 the Proportional Numbers of the two Sexes throughout the Animal 

 Kingdom. — On the Limitation of the Numbers of the two Sexes 

 tbrough Natural Selection. 



With animals which have their sexes separated, the 

 males necessarily differ from the females in their organs 

 of reproduction ; and these afford the primary sexual char- 

 acters. But the sexes often differ in what Hunter has 

 called secondary sexual characters, which are not directly 

 connected with the act of reproduction ; for instance, in 

 the male possessing certain organs of sense or locomotion, 

 of which the female is quite destitute, or in having them 

 more highly developed, in order that he may readily find 

 or reach her ; or again, in the male having special organs 

 of prehension so as to hold her securely. These latter 

 organs of infinitely-diversified kinds graduate into, and in 

 some cases can hardly be distinguished from, those which 



