Chap. XVIII. Mam ma Is — Sum mary. 553 



acquired or modified through that form of selection which I 

 have called sexual. This does not depend on any superiority in 

 the general struggle for life, but on certain individuals of one 

 sex, generally the male, being successful in conquering other 

 males, and leaving a larger number of offspring to inherit their 

 superiority than do the less successful males. 



Fig. 78. 



Cercopithecus diana (from Brehm). 



There is another and more peaceful kind of contest, in which 

 the males endeavour to excite or allure the females by various 

 charms. This is probably carried on in some cases by the power- 

 ful odours emitted by the males during the breeding-season ; the 

 odoriferous glands having been acquired through sexual 

 selection. Whether the same view can be extended to the voice 



