94 



THE INVERTEBRATA 



reproduction or become gamonts. These undergo syzygy, coencyst- 

 ment, and gamogony. The gametes unite, and the zygotes form small 

 oocysts ("spore cases") within the gamocyst. In its case each zygote 

 divides into a bundle of sporozoites. The spores are set free and 

 swallowed by new members of the host species, in whose intestine the 

 spore cases are digested and the process repeated. 



Fig. 76. A diagram of the life cycle of Schizocystis. 1-4, Schizogony. 5, 

 Gamonts. 6, Syzygy. 7-9, Gamogony in a cyst (gamocyst). 10, 11, Syn- 

 gamy. 12, Freed spore case containing sporozoites resulting from sporogony. 



Ophryocystis (Fig. 77). Parasitic in the Malpighian tubules of 

 beetles. The cushion-shaped trophozoites are attached to the host's 

 cells by branched processes. After several generations of schizogony, 

 they become free gamonts, enter into syzygies, encyst, and within the 

 gamocyst undergo two divisions, whereby each forms one definitive 

 gamete and a binucleate enveloping cell which perhaps represents 

 abortive gametes. Syngamy then takes place, and the zygote divides 



