210 SPOROZOA, 



6 (5). Schizogony in the red blood-corpuscles of 

 Vertebrates, with division into two or 

 four ; of varying size and shape, and 



have a tendency to arrangement in [p. 301. 



couples of pear-shaped individuals Babesiidse Poche, 



1. Family H^MOPROTEID^ Doflein, 1916. 



Schizogony takes place in the endothehal cells of the blood- 

 vessels of Vertebrates. Certain merozoites penetrate into the 

 circulating red blood-ceUs, in which they develop into gameto- 

 cytes. If the blood is taken up by a specific blood-sucking 

 Invertebrate host, the gametoc3^es develop into gametes, 

 which unite to form the zygotes, and the latter undergo 

 sporogony, as in the family Plasmodiidse. 



Remarks. — It is important to remember that the schizogony 

 cycle can only be observed in sections or smears from the 

 internal organs of the host. In the absence of definite know- 

 ledge regarding the occurrence of schizogony in the internal 

 organs, the generic position can only be inferred from the 

 morphology of the parasites themselves and their occurrence in 

 relation to the nucleus of the infected corpuscle. In Hsemo- 

 jproteus the organism is halter-shaped and grows round the 

 nucleus without displacing it, whereas in Proteosoma (family 

 Plasmodiidse) the nucleus of the red blood-corpuscle is ordinarily 

 pushed to one side by the invading organism. 



Stiles (1925) gives " ookinete not known to encyst " as the 

 character which serves to distinguish the family Haemoproteidse 

 from the family Plasmodiidse. This statement appears to be 

 based on the earlier work of Aragao. Helen Adie (1915) 

 followed the complete development of the ookinete of 

 Hssmoproteus columbas in the fly Lynchia maura. She 

 confirmed that work in 1924, and Aragao (1927) also con- 

 firmed it. Numerous oocysts were found in the wall of the 

 stomach of the fly, and the various stages of development 

 were found to resemble closely those of malarial parasites in 

 mosquitoes. 



Key to India Genera. 



1 (2). Young gametocytes enter the red blood- 



corpuscles ; when fully developed the 

 gametocy te is halter-shaped, and produces 

 pigment granules from the haemoglobin. . [Kruse, p. 211. 



2 (1) Gametocytes invade the immature red H^mopboteus 



blood-cells which have not yet produced 



haemoglobin, the host-cell is profoundly 



altered, becoming an elongated spindle, 



and the gametocyte does not produce [Danilewsky, p. 238. 



any pigment Leucocytozoon 



