Chap. VIIL] SEXUAL SELECTION. 263 



be still more efficient ; whether the prei3onderance was 

 only occasional and local, or permanent ; whether it oc- 

 curred at birth, or subsequently from the greater destruc- 

 tion of the females ; or whether it indirectly followed from 

 the practice of polygamy. 



The Male generally more modified than the Female. — 

 Throughout the animal kingdom, when the sexes differ 

 from each other in external appearanee, it is the male 

 which, with rare exceptions, has been chiefly modified ; 

 for the female still remains more like the young of her 

 own species, and more like the other members of the same 

 group. The cause of this seems to lie in the males of 

 almost all animals having stronger passions than the fe- 

 males. Hence it is the males that fight together and sedu- 

 lously display their charms before the females ; and those 

 which are victorious transmit their superiority to their 

 male offspring. Why the males do not transmit their 

 characters to both sexes will hereafter be considered. 

 That the males of all mammals eagerly pursue the females 

 is notorious to every one. So it is with birds ; but many 

 male birds do not so much pursue the female, as display 

 their plumage, perform strange antics, and pour forth 

 their song, in her presence. With the few fish which have 

 been observed, the male seems much more eager than the 

 female ; and so it is with alligators, and apparently with 

 Batrachians. Throughout the enormous class of insects, 

 as Kirby remarks, 11 " the law is, that the male shall seek 

 the female." With spiders and crustaceans, as I hear 

 from two great authorities, Mr. Blackwall and Mr. C. 

 Spence Bate, the males are more active and more erratic 

 in their habits than the females. With insects and crus- 

 taceans, when the organs of sense or locomotion are pros- 



11 Kirby and Spence, 'Introduction to Entomology,' vol. iii. 1826, 

 p. 342. 



