244 SPOROZOA. 



210. Leucocytozoon (?) sp. 



■fLeucocytozoon (?) sp., de Mello, 1937 a, pp. 105-6, 



Form round. No sexual differentiation. Great tendency 

 to aberrant forms in addition to round ones of regular t3rpe. 

 Nucleus crescentic or irregular and very large in some speci- 

 mens ; oval, with a more deeply staining line or point in others. 



Habitat. — Blood of Oriolus xanthomus xanthornus (Linn.) : 

 Portuguese India. 



2. Family PLASMODIID^ Mesnil, 1903. 



Schizogony takes place within the red blood- corpuscles of 

 s, Vertebrate host. During the growth of the trophozoite, 

 pigment, known as hsemozoin, is formed from the haemoglobin 

 of the corpuscle. Gametocytes also occur in the red blood- 

 curpuscles and contain pigment. Further development takes 

 place in the body of a mosquito. Microgametes are produced 

 by exflagellation. Zygote becomes a motile ookinete, and 

 later encysts as an oocyst. The oocyst grows enormously 

 in size, and innumerable sporozoites are produced, without 

 the formation of sporoblasts or sporocysts. 



The family, according to many authorities, contains a single 

 genus, Plasmodium, as they consider Plasmodium Marchiafava 

 & Celh, Laverania Grassi & Feletti, and Proteosoma Labbe as 

 congeneric. Doflein (1916) and Reichenow (1929) consider 

 these as distinct, and Reichenow also includes the genus 

 Dactylosoma in the family. According to Reichenow it would 

 be desirable to retain the generic name Proteosoma for the 

 malarial parasites of birds, and to refer the malarial parasites 

 of the reptiles also to it. He also considers it justifiable to 

 place the human tropical parasite of mahgnant tertian malaria 

 in a separate genus, Laverania. Both the genera Proteosoma 

 and Laverania show some resemblance to Coccidia in that the 

 gametocytes are spherical, oval, vermiform or sausage-shaped, 

 whilst in Plasmodium the gametocytes are circular and disc- 

 like. The genus Laverania, which includes parasites of man 

 and anthropoid apes, is not easily marked off from the 

 Proteosoma of birds. Slender gametocytes, like those charac- 

 teristic of Laverania, occur also in some species of Proteosoma, 

 and the characteristic that schizogony takes place in the internal 

 organs in the case of Laverania has been found to occur, 

 according to the recent researches of Hartmann, in Proteosoma 

 also. 



Of the English authors, Thomson and Woodcock (1922) 

 justified the retention of Laverania as a separate genus on the 

 ground that the gametocyte or crescent is enclosed by a capsule, 



