482 



TELOSPORIDIA 



cell, as an oval, fusiform, or club-shaped mass of cytoplasm with a large, 

 homogeneous nucleus. As this trophozoite grows it becomes encapsuled, 

 and forms the schizont, which, when fully grown, is a large oval or rounded 

 body, with a central nucleus, and with the cytoplasm filled with spherules. 

 This schizont usually lies in an enlarged and dehsemoglobinized cell, in which 

 it is seen to be surrounded by a thick capsule, which shows three definite 

 cleavage lines, of which two cross it transversely a short distance from either 

 pole, while the third is longitudinal. 



There are two varieties of schizonts, one which gives rise to relatively few 

 large merozoites called ' macromerozoites,' while the other breaks up into 

 relatively many small micromerozoites. 



Fig. 153. — Hcemogregavina mirabilis Castellani and Willey, showing 

 THE Escape of the Gametocyte from its Capsule. 



(After Castellani and Willey.) 



This difEerentiation is considered to be a prelude to the formation of macro- 

 and micro-gametocytes. Usually the schizont divides into eight, twelve, or 

 sixteen merozoites, which may escape from the enclosing cell in the peripheral 

 blood, but more generally do so in an organ, such as the liver, lung, or bone- 

 marrow. Other hsemogregarines, like H. jaculi and H. muris, undergo seg- 

 mentation in the cells of an organ such as the liver. 



The gametocytes are easily recognizable from the schizonts, as they lie bent 

 up in the capsule, and because the enclosing cell is not afiected by the para- 

 site. It is not possible at present to differentiate between the macro- and 

 the micro-gametocyte. 



Fig. 154. — Hcsmogregarina seligmanni Fig. 155. — Hcsmogregarina seligmanni 



Sambon : Free Sporont. Sambon. 



(After Sambon.) According to Sambon, this figure 



^ ' probably represents conjugation. 



(After Sambon.) 



In shed blood they quickly escape from the capsule, which may be seen to be 

 double, for Sambon depicts a gametocyte which has escaped from the outer 

 wall of the capsule, but has the inner wall still adherent. 



When free, they are seen to be of an elongated, club-shaped form. At the 

 thicker end, which is anterior, there projects a small retractile rostrum or 

 beak, from which a clear line, probably a cytostome or pharynx, runs back- 

 wards through the cytoplasm, and ends near the nucleus. 



The ectoplasm shows at times a difEerentiation into three layers — epicyte, 

 sarcocyte, and myocyte — ^while the endoplasm is granular, and about its 

 middle is found the round or oval nucleus. 



According to Sambon, conjugation can be seen taking place in blood spread 



