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HANDBOOK OF PROTOZOOLOGY 



Family 1 Plasmodiidae Mesnil 



Genus Plasmodium Marchiafava and Celli. This genus 

 contains the important malarial organisms of man and birds. 

 As stated above, the schizogony takes place in the erythrocyte 

 of a vertebrate host and anisogamy and sporozoite-formation 

 occur in the mosquitoes belonging to the genus Anopheles or 

 Culex. Numerous species. Three species in man. , ^ Sfe; 



Plasmodium vivax (Grassi and Feletti) (Fig. 121, a~g). The 

 parasite of the benign tertian malaria of man. Schizogony is 



Fig. 121 a-g. Plasmodium vivax. XIOOO. 

 h-n. P. falciparum. X 1000. 

 o-u. P. malariae. XlOOO. 

 a-e, h-1, o-s, schizogony; f, m, t, microgametocytes; g, n, u, macrogameto- 



cytes). 



completed in 48 hours. The infected erythrocyte becomes en- 

 larged. As to its distinction with the other two species see 

 below. Widely distributed over the temperate and tropical 

 countries. 



Plasmodium falciparum (Welch) (Fig. 121, h-n). The para- 

 site of the malignant tertian, subtertian, or aestivo-autumnal 

 malaria of man. Schizogony is completed in about 48 hours, 

 but frequently irregular. The schizonts adhere to the capil- 

 lary wall, to which the malignancy of the species is attributed. 

 The gametocytes are crescentic; some authors therefore place 

 this species in another genus, Laverania. Of more limited dis- 

 tribution in tropical and subtropical regions of the world. 



