THE ANIMAL KINGDOM 



377 



f< ■'•] 







A B C 



Fig. 210. — Gregarines. A, Gregarina blatlarum, showing a chain of two indi- 

 viduals. (After Cuenot.) B, Corycella armata. (After Leg er .) C, Stylorhynchus 

 longicollis. (After Schneider.) e, epimerite by means of which the parasite is 

 attached to tissues of the host; p, protomerite; d, deutomerite. 



5 6 ' 8 



Fig. 211. — Life history of Coccidium schubergi, parasitic in the intestinal 

 epithelium of the centipede, Lithobius forficatus. (After Schaudinn.) Cysts 

 (8) swallowed with food are dissolved by digestive fluid. Each cyst contains 

 four spores each of which in turn contains two sporozoites. The sporozoite 

 attacks the intestinal cell (1), enlarges to form a schizont (3) which undergoes a 

 rapid nuclear division eventually forming merozoites (4). The latter reinfect 

 other cells, repeating the cycle. Sooner or later schizogony is replaced by spo- 

 rogony which leads to the formation of microgametocytes (2) and macrogam- 

 etocytes (5). Figure 6 shows a macrogamete surrounded by a number of 

 microgametes. The fertilized macrogamete becomes encysted, forming four 

 sporoblasts (7) each of which develops two sporozoites (8). The latter remain 

 encysted until favorable conditions arise for their development in another host. 

 e, intestinal cell; z, sporozoite. 



