REPRODUCTION 



181 



the ovary and containing the eggs. Spermatozoa are 

 produced in large numbers by the testicular cells which 

 mature before the ova (protandrism) and are liberated 

 by rupture of the ectodermal covering. One ovum is 



FIG. 77. Colony of Obelia geniculata (magnified). (After Masterman.) 



usually all that matures in the ovary. It takes an 

 amoeboid form also escaping by rupture of the ectoder- 

 mal layer, protruding between its cells, in which position 

 it is reached by the spermatozoa, one of which conjugates 

 with it. When thus fertilized, it loses its amoeboid 



