'54 



THE ANTMAL PARASITES OF MAN 



The nucleus of haemogregarines is usually near the middle of the 

 parasite, but may be situated nearer one end. The body of the 

 parasite may be lodged in a capsule (" cytocyst "). There is much 

 variation in size and appearance among haemogregarines. Some are 

 small (Laiikesterella) ; some attack the nucleus of the host cell (Karyo- 

 lysus) ; others have full grown vermicules larger than the containing 

 host corpuscle, and so the haemogregarines bend on themselves in 

 the form of U (fig. 78, 6). Schizogony often occurs in the internal 

 organs of the host, sometimes in the circulating blood. 



The haemogregarines occurring in the white cells (mononuclears 

 or polymorphonuclears) of mammals have been referred to a separate 

 genus, Leucocytogregarina (Porter) or Hepatozoon (Miller). Such 

 leucocytogregarines are known in the dog (fig. 79), rat, mouse, palm- 

 squirrel, rabbit, cat, etc. Schizogony of these forms occurs in the 

 internal organs, such as the liver, lung and bone-marrow of the hosts. 



FlG. 78. Hremogregarines from lizards, a, H, schaudinni, var. africana, from Lacerta 

 ocellata ; b, H. nobrei from Lacerta muralis ; c, H. marceaui in cytocyst, from Lacerta 

 muralis. (After Franga.) 



They are apparently transmitted by ectoparasitic arthropods, such as 

 ticks, mites, and lice. 



A few haemogregarines are known to be parasitic in the red blood 

 corpuscles of mammals. Such are H. gerbilli in the Indian field rat, 

 Gerbillus indicus ; H. balfouri (jaculi) in the jerboa, Jacuhis jacnlns, 

 and a few species briefly described from marsupials. These parasites 

 do not form pigment. 



Strict leucocytic gregarines have been described from a few birds 

 by Aragao and by Todd. 



The sporogony of haemogregarines is only known in a few cases, 

 and in those affinity with the Coccidia is exhibited. In fact, the 

 Haemogregarines are now classified by some authors with the 

 Coccidia. 



(5) The Babes la or Piroplasma type. These are small parasites of 

 red blood corpuscles of mammals. They do not produce pigment. 

 They are pear-shaped, round or amoeboid in Babesia, bacilliform 



