SEXUAL REPRODUCTION. 



273 



plete loss of motility by the female cell (fig. 304). When 

 these differences exist in the sex cells their union is no 

 longer called conjugation, but fertilization, the active male 

 cell being said to fertilize the quiescent female ( ell. 



377. Sex organs. — A further stage in the development of 

 sexuality is reached when the cells producing the sperms or 



Fig 

 carpus. /■. sperm 



Differentiation of gametes in some marine algae 

 lost 



1. ./. 1 

 the extreme "I difference in she in gametes. All magnified equally (about 700 diam.), 



egg of Za 



before fertilization which is about to occur in (/ 



ke gametes of Keto- 

 ne egg loses its cilia and rounds itself 

 . sperm, _/. egg of incus. This is 



the eggs are differentiated. The cell or the Organ producing 

 the egg has been known by various names in different groups 

 of plants. An appropriate general name for it, without refer- 

 ence to its structure, is the ovary. (See further* 335.) 



