DIVISION AND MORPHOGENESIS 



39 



phoront, instead of awaiting" ecdysis, iiiooiilates itself in the 

 crab. Leucocytes will form a harriei* and isolate the para- 

 site in a limited sector in which th(> ciliate feeds. The size 



Empty phoretic cyst 



Young trophont 

 V (blood form) 

 or hypertrophont 



Grown-up sanguicolous hypertrophont or hvpertomont 



Mature 



.'\u\ icolous 



trophont 



Hypertomite 

 or young 



exuvicolous 

 trophont 



^^^ 



Fig. 13. Synophrya hypertrophica : life cycle. The division of the 

 internal hypertrophont is induced by ecdysis. The hyperpalintomy 



yields trophonts. 



increases enormously. The macronucleus is altered into a 

 complicated netw^ork. The grown-up ^^hypertrophont" will 

 now wait for ecdysis. The sexual behavior of the male 

 crab allows us to see what happens before ecdysis takes 

 place. It is known that copulation of crabs takes place only 

 immediately after ecdysis of the female, between a hard 

 male and a soft female. In order to copulate, the male 



