SEX IN PRO lOZOA 



189 



Fig. S. Life cycle of NejTiatopsis ostrearuni from Prytherch (1940), redrawn. 



1, escape of sporozoite in intestine of crab; 2, attachment to intestinal epithelium; 

 3, development of epimerite and septum; 4, precocious syzygy of young trophozoites; 

 5, reattachment to intestinal wall; 6, more mature trophozoite; 7, syzygy of a pair of 

 trophozoites; 8, full-grown pair of trophozoites (gamonts), attachment to intestinal 

 wall; 9, encystment of gamonts forming gametocyst; 10, rupture of gametocyst 

 releasing clusters of sporozoites (gymnospores); 11, single gymnospore discharged 

 into sea water, ready to enter an oyster gill; 12, engulfment of gymnospore by 

 oyster phagocyte, separation of sporozoites; 13-16, growth of sporozoites, each 

 becoming enclosed in a sporocyst; 17, fully developed spore. 



