CHAPTER LVI 



CLASS III SPOROZOA 1 



SUB-CLASS TELOSPORIDIA 



HEMOSPORIDIA 



THE Hemosporidia and Sarcosporidia are the only members of this 

 order of medical interest. The hemosporidia belong to the sub-class 

 Telosporidia of the Sporozoa, because spore formation begins at the 

 end of the life cycle. 



The systematists have not yet agreed upon the proper classification 

 of this group of parasites; consequently the older arrangement will 

 be followed. They are, like the coccidia, parasites of cells, at least 

 during the schizogenous cycle ; all change hosts to some insect for the 

 sporogenous cycle. As the name implies, they live in blood cells and 

 are rapidly growing ameboid bodies, which, beginning as sporozoites, 

 penetrate the host cells and develop into trophozoites. These grow 

 rapidly to adult segmenting parasites, in which case they are called 

 schizonts, or to sexual forms, or gametes, when they are termed 

 sporonts. In the course of their development, most species produce 

 melanin from the destruction of the hemaglobin. 



The nucleus, which is readily stained, is single and posesses a 

 karyosome ; the mature schizont divides into many small forms called 

 merozoites, and these, when freed by the rupture of the degenerated 

 erythrocyte, escape into the blood plasma, and if not phagocyted, 

 penetrate other erythrocytes and repeat the asexual or schizogenous 

 cycle. The pigment and undivided portion (restkorper) of the cyto- 

 plasm of the mother cell accumulate in the bone marrow, spleen and 

 other viscera. 



After a number of cycles of asexual multiplication have been lived 

 through, a new development takes place and sexual forms begin to 

 appear in the circulation. These grow to large size, yet show no indi- 

 cation of division into merozoites and were at one time considered 



1 For classification, see page 1049. 



1098 



