HAEMOSPORIDIA 611 



schizonts: In about 48 hours, schizonts nearly fill the host cells; 

 rounded; haemozoin granules begin to collect into a mass; nuclear 

 divisions produce 6-12 merozoites which are the largest of the three 

 species and may often be arranged in a circle around a haemozoin 

 mass. Gametocytes : Circular; with haemozoin granules. Macrogame- 

 tocytes stain more deeply and contain a small, more deeply staining 



a b c 



g h 



# 



i j k I 



Fig. 261. Plasmodium malariae, X1535 (Original), a, ring-form; b-e, 

 band-form schizonts; f-i, schizogonic stages; j, merozoite formation; k. 

 macrogametocyte, 1, microgametocyte. 



nucleus and coarser granules; microgametocytes stain less deeply 

 and contain a larger lightly stained nucleus and finer and numerous 

 granules. The organism invades most frequently mature red cor- 

 puscles (Kitchen, 1939). 



The quartan fever parasite is distributed in the tropics and sub- 

 tropics, though it is the least common of the three species. As a rule, 

 in an area where the three species of Plasmodium occur, this species 

 seems to appear later in the year than the other two. 



P. ovale Stevens (Fig. 262). The Ovale or mild tertian fever para- 

 site; schizogony in about 48 hours; its morphological characters re- 

 semble both P. vivax and P. malariae. Ring forms: Similar to 

 those of the two species just mentioned; Schiiffner's dots appear 

 early. Growth period: Infected erythrocytes are more or less oval 

 with irregular fimbriated margin; slightly enlarged; not actively 

 amoeboid, sometimes in band-form; with dark brown haemozoin 



