494 PROTOZOOLOGY 



schizonts: In about 48 hours, sehizonts nearly fill the ho.st cells; 

 rounded; haemozom 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 deeph' and contain a small, more deeply staining 



" ^m 



V^Ek JHp^ ^mmam mmBBs 



^w ^"W^ ^w ^P^ 



i i k I 



Fig. 230. 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 quartan fever is distributed in the tropics and subtropics. 

 though it is the rarest of the three species. As a rule, in an area where 

 the three species of Plasmodium occur, this seems to appear later 

 in the year than the other two. 



P. ovale Stevens (Fig. 231). The Ovale or mild tertian fever para- 

 site ; schizogon}^ 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 activel}' 

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

 granules; Schiiffner's dots abundant. Schizogonic stages: 6-12 mero- 



