HAEMOSPORIDIA 



285 



lated into a new victim (g). The schizogony occurs regularly, 

 and it is thought that the typical malarial fever is caused by 

 some toxic substance which is liberated into the blood plasma 

 when the merzoites become set free in the latter. 



The Haemosporidia are divided into three families, as follows: 



Schizogony in the peripheral blood of vertebrates Family 1 Plasmodiidae 



Gametocytes in the peripheral blood corpuscles; schizogony elsewhere . . 



Family 2 Haemoproteidae 



Minute parasites of erythrocytes; incompletely known. . . .Family 3 Babesiidae 



Fig. 120 Life-cycle of Plasmodium vivax. (Compiled after various authors). 



a. Sporozoite entering human blood plasma. 



b. Sporozoite entering erythrocyte. 



c. Young schizont. 

 d-f. Schizogony. 



g, h. Macrogametocytes. 

 i, j. Microgametocytes. 

 k. Microgametes formed in the stomach of the mosquito. 

 1. Union of gametes, 

 m. Zygote or ookinete, penetrating through gut wall, 

 n. Rounding up of an ookinete between the gut wall and the elastic 



membrane. 

 o. Oocyst in which sporozoites are being developed, 

 p. Mature oocyst ruptured and the sporozoites set free in the body fluid. 

 q. Sporozoites entering the salivary gland. 



