MALARIA AND ITS TRANSMISSION 21 



2, //). The segmenting stage (Fig. 2, c'), which is rarely 

 seen in the blood, is said to produce only from eight 

 to ten merozoites, according to Stephens and Chris- 

 tophers, while Deaderick states that the number varies 

 from five to twenty-five and over. Characteristic 

 crescents (Fig. 1) or gametocytes (sexual forms) are 

 commonly observed in cases of ten or more days' 

 duration. Crescents occur in this species only. The 

 female crescents show the chromatin material well 

 concentrated in the mid-region, with slight stippling 

 at both ends, while the male crescents present a thinly 

 scattered chromatin with both ends hyaline (these are 

 also called hyaline bodies or hyaline crescents). Cer- 

 tain relapses after some months' latency are said to 

 be traceable to a parthenogenetic cycle in the female 

 crescents, which produce merozoites, and these attack 

 the red blood corpuscles, as do the ordinary sporulated 

 forms. 



Enlarged parasitized corpuscles occur in this species, 

 but merely as a coincident, since enlarged corpuscles 

 commonly occur in anaemia, and these may be entered 

 by the sporozoites. 



b. Plasmodium vivax {Hcemamceba vivax) is the 

 cause cf tertian fever or benign tertian malaria of 

 temperate climates, also the tropics and subtropics, 

 with recurrent paroxysms regularly every forty-eight 

 hours. In these parasites the pigment granules (Fig. 

 2, b) are very fine and are distributed throughout the 

 red corpuscle as SchufTner's dots. The parasitized 



