196 



SEX IN MICROORGANISMS 



Fig. V. 



1-18, outline of life cycle of Aggregata ebertbi, from Dobell (1925). 1, fertilized 

 zygote; 2, first nuclear division in zygote; 3, later nuclear divisions in zygote; 4, 

 formation of sporoblasts; 5, mature spore; 6, release of sporozoites in digestive tract 

 of crab; 7-10, growth of schizont and formation of merozoites; 11, 12, passage of 

 merozoites to cuttlefish; 13-15, development of microgametes; 16-18, development of 

 macrogamete; 18, fertilization. 19-26, sporulation of oocyst of Chagasella sp., from 

 Gibbs (1944). 19, first nuclear division in young oocyst; 20, binucleate stage in 

 oocyst; 21, one nucleus divides; 22, the three nuclei divide as cytoplasm divides into 

 three parts; 23, three young spores; 24, 25, further development of spores; 26, 

 mature spore with four sporozoites. (All illustrations redrawn.) 



