86 MANUAL OF HUMAN PROTOZOA 



oocysts between the base of the epithehum and outer mem- 

 brane of the stomach (Fig. 21, 14), Withm the oocysts, 

 repeated nuclear divisions produce many sporozoites (Fig. 

 21, 15), When fully mature, the oocysts rupture and the 

 sporozoites are set free in the haemolymph through which 

 they migrate to the salivary glands (Fig. 21, 16, IV). The 

 sporozoites finally make their way through the gland epi- 

 thelium and enter the duct of hypopharynx. They are now 

 ready to infect a human victim when the mosquito goes 

 after another blood meal. The development in the mos- 

 quito is completed in about 8-14 days. 



1. Plasmodium vivax (Grassi and Feletti 1890) 



This organism is the cause of the benign tertian malaria. 

 It is seldom fatal. The schizogony is completed in 48 hours. 

 Thus chill and fever appear every third day. It is the most 

 widely distributed species in the tropical and subtropical 

 regions as well as in the temperate zone. It has been 

 reported as far north as the Great Lakes region in North 

 America, England, southern Sweden and northern Russia 

 in Europe, and as far south as Argentina, Australia, and 

 Natal in Africa. Generally speaking this species predomi- 

 nates in the spring and early summer more than the other 

 species of Plasmodium. In routine detection and identifica- 

 tion, stained blood films are examined for the organisms. 



Schizonts 



1. Ring forms. Usually found soon after the characteris- 

 tic malarial attack has passed ofl:. The young merozoite 

 which has entered an erythrocyte recently is a ring form 



