HAEMOSPORIDIA 495 



zoites. Gamctocytes: Resemble closely those of P. malariac; host cells 

 with Schiiffner's dots and slightly enlarged. 



This organism appears to be confined to Africa and Asia (Philip- 

 pine Islands and India). Several malariologists doubt the validit}^ of 

 the species. 



The malarial parasites are ordinarily studied in stained blood 

 films (p. 727). Table 9 will serve for differential diagnosis. 



Several species of Plasmodium have been observed in primates 

 and monkeys, some of which resemble the human species. Species 

 are known to occur in various other mammals. 



W' ^^- 



i 



# 



e f g h 



Fig. 231. Plasmodium ovale, X1535 (Original), a, ring-form; b, c, 

 growing schizonts; d-f, schizogonic stages; g, macroganietocyte; h. micro- 

 gametoeyte. 



Man}^ species of Plasmodium have been reported from numerous 

 species of birds in w^hich are observed clinical symptoms and path- 

 logical changes similar to those which exist in man with malaria 

 infection. In recent ^^ears the exoerythrocytic stages have been in- 

 tensively studied in these forms. According to Hegner and co- 

 workers the erythrocytes into which merozoites enter are often the 

 most immature erythrocytes (polychromatophilic erythroblasts). 

 Hewitt (1940) gave an excellent digest of available information on 

 avian Plasmodium. The species of avian Plasmodium are transmit- 

 ted by adult female mosquitoes belonging to Culex, Aedes or Theo- 

 baldia. More or less distinct species are here briefly described. 



P. relictmn Grassi and Feletti (P. praccox G. and F.; P. inconslans 

 Hartman) (Fig. 232, a). In English sparrow {Passer domesticus) and 

 other passerine birds; schizogony varies in different strains, in 12, 

 24, 30 or 36 hours; 8-15 or 16-32 merozoites from a schizont; game- 

 tocytes rounded, with small pigment granules; host-cell nucleus dis- 

 placed; canaries (Serinus canaria) susceptible; many strains; 

 transmitted by Culex, Aedes and Theobaldia; widely distributed. 



