566 



CERCOMONAS, TRICHOMONAS, HERPETOMONAS 



its origin." At the base of the flagellum, just outside of the body, 

 is a small basal granule. Reproduction occurs by longitudinal division. 

 The nucleus divides by a primitive process of mitosis, the granules 

 being equally distributed. This nuclear division is preceded by 

 division of the blepharoblast and of the flagellum, which in this 

 case appears to divide throughout its entire length, instead of one 

 being formed as in some trypanosomes by outgrowth from the blephar- 

 oblast. Conjugation has been described by Prowazek as taking place 

 between forms which are not sexually differentiated beyond the 

 fact that one appears to be denser and larger than the other. After 

 conjugation a permanent resting cyst is formed by the fertilized 

 cell, and in this condition the parasite passes from the intestine with 

 the feces of the host. Infection of new hosts usually takes place 

 by ingestion of these permanent cysts with the food. 



FIG. 197 



Herpetomonas Donovani, unequal division to form slender flagellated individuals. 

 (After Leishman.) 



The genus herpetomonas has assumed considerable importance, 

 first, in consequence of Schaudinn's claim that the hemosporidia of 

 birds are a stage in the life cycle of herpetomonas, 1 and secondly, of 

 greater importance, because it is now known that a herpetomonas is 

 the cause of a widespread tropical disease of man. 



This disease, which occurs in India, China, Egypt, Arabia, Tunis, 

 Algiers, and other tropical countries, is known as kala azar, tropical 

 febrile splenomegaly, dum-dum fever, and by other names. Leish- 

 man discovered peculiar bodies in the spleen of a person dead from the 

 disease and his observation was first confirmed by Donovan and later 

 by others, including Marchand, Rodgers, and Christopher. These 

 bodies, first known as the Leishman-Donovan bodies, are found in 

 great numbers in the large cells of the spleen or liver. They are 

 round or oval, or rather cockle-shell-shaped, and have two chro- 



1 This, as already explained, is denied by Novy and his associates. 



