Ciiap. VIII. Sexual Selection. 2.21 



of males over females will be still more efficient ; -whether the 

 preponderance is only occasional and local, or permanent; 

 whether it occurs at birth, or afterwards from the greater de- 

 struction of the females ; or whether it indirectly follows from 

 the practice of polygamy. 



The Male generally more modified than the Female. — Throughout 

 the animal kingdom, when the sexes differ in external appearance, 

 it is, with rare exceptions, the male which has been the more 

 modified ; for, generally, the female retains a closer resemblance 

 to the young of her own species, and to other adult members of 

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

 of almost all animals having stronger passions than the females. 

 Hence it is the males that fight together and sedulously display 

 their charms before the females ; and the victors transmit their 

 Superiority to their male offspring. Why both sexes do not thus 

 acquire the characters of their fathers, will be considered here- 

 after. That the males of all mammals eagerly pursue the 

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

 cock birds do not so much pursue the hen, as display their 

 plumage, perform strange antics, and pour forth their song in 

 her presence. The male in the few fish observed seems much 

 more eager than the female; and the same is true of alligators, 

 and apparently of Batrachians. Throughout the enormous class of 

 insects, as Kirby remarks, 18 " the law is, that the male shall seek 

 " the female." Two good authorities, Mr. Black wall and Mr. C. 

 Spence Bate, tell me that the males of spiders and crustaceans 

 are more active and more erratic in their habits than the females. 

 When the organs of sense or locomotion are present in the one 

 sex of insects and crustaceans and absent in the other, or when, 

 as is frequently the case, they are more highly developed in the 

 one than in the other, it is, as far as I can discover, almost 

 invariably the male which retains such organs, or has them most 

 developed; and this shews that the male is the more active 

 member in the courtship of the sexes. 19 



18 Kirby and Spence, ' Introduc- females of this species are impreg- 

 tion to Entomology,' vol. iii. 1826, nated by^the males which are born 

 u. 342. in the same cells with them ; but 



19 One parasitic Hymenopterous it is much more probable that the 

 insect (Westwood, ' Modern Class, of females visit other cells, so that 

 Insects,' vol. ii. p. 160) forms an close interbreeding is thus avoided, 

 exception to the rule, as the male We shall hereafter meet in various 

 has rudimentary wings, and never classes, with a few exceptional oases, 

 quits the cell in which it is born, in which the female, instead of 4 hn 

 whilst the female has well-develcped male, is the seeker and wooer, 

 wings. Audouin believes that the 



