Chap. VIII.] SEXUAL SELECTION. 265 



no advantage and some loss of power if both sexes were 

 mutually to search for each other ; but why should the 

 male almost always be the seeker? With plants, the 

 ovules after fertilization have to be nourished for a time ; 

 hence the pollen is necessarily brought to the female or- 

 gans — being placed on the stigma, through the agency of 

 insects or of the wind, or by the spontaneous movements 

 of the stamens ; and with the Alga?, etc., by the locomo- 

 tive power of the antherozooids. "With lowly-organized 

 animals permanently affixed to the same spot and having 

 their sexes separate, the male element is invariably 

 brought to the female ; and we can see the reason ; for 

 the ova, e'ven if detached before being fertilized and not 

 requiring subsequent nourishment or protection, would 

 be, from their larger relative size, less easily transported 

 than the male element. Hence plants 14 and many of the 

 lower animals are, in this respect, analogous. In the case 

 of animals not affixed to the same spot, but enclosed 

 within a shell with no power of protruding any part of 

 their bodies, and in the case of animals having little 

 power of locomotion, the males must trust the fertilizing 

 element to the risk of at least a short transit through the 

 waters of the sea. It would, therefore, be a great advan- 

 tage to such animals, as their organization became per- 

 fected, if the males when ready to emit the fertilizing ele- 

 ment, were to acquire the habit of approaching the female 

 as closely as possible. The males of various lowly-organ- 

 ized animals having thus aboriginally acquired the habit 

 of approaching and seeking the females, the same habit 

 would naturally be transmitted- to their more highly-de- 

 veloped male descendants; and in order that they should 



14 Prof. Sachs ('Lekrbucli dcr Botanik,' 1870, s. G33) in speaking of 

 the male and female reproductive cells, remarks : " Verhiilt sick die eine 

 bei dcr Vereinigung activ, .... die andere erscheint bei der V«reiui- 

 gung passiv." 



