HMMOGREGARINES OF THE MAMMALIA 483 



on an ordinary slide. The further history of the cycle of sporogony is only 

 known in H. muris and H. canis ; the former has already been described, and 

 the latter will be mentioned later. 



Recently Henry has shown that Balfour's infective granule is a phase in 

 the life-history of H. simondi. Haemogregarines can be cultivated in Nicolle's 

 blood-agar medium. 



No haemogregarines are at present known in birds nor, until recently, in 

 man, but some peculiar parasites have been seen by Castellani and Willey and 

 others in the peripheral blood of man (p. 538); whether these will prove 

 to be haemogregarines, or whether they belong to some other order of the 

 protozoa, remains to be seen. Krempf has recently described a haemogregarina 

 in the spleen of a Chinese. 



Classification. — As already mentioned, the species of the genus Hamogrega- 

 rina Danilewsky, 1 885, will be arranged according to their hosts. Some authors 

 recognize Hepatozoon Miller, 1908, with H. muris Balfour, 1905, as a type, 

 and distinguish it by living in leucocytes, and sometimes undergoing schizo- 

 gony in the cells of the internal organs. 



H^MOGREGARINES OF THE MAMMALIA. 

 Haemogregarina hominis Krempf, 191 7. 



Definition. — Hamogregarina found only in the spleen of man suffering from 

 splenomegaly, in China. 



Remarks. — The infection appears to have been acquired in China. 



Morphology. — The parasite lives in red cells which increase in size. Inside 

 the red cells the organism lies in a capsule, 10 X 5 microns, and is vermicular 

 in shape, being bent or twisted. There is a granular nucleus, mostly central 

 in position. Parasites which have escaped from the red cells and lie free in 

 the plasma are identical with those found in the cells. 



Life-History. — Unknown . 



Pathogenicity. — Believed to cause splenomegaly. 



Haemogregarina muris Balfour, 1905. 

 Synonyms. — Leucocytozoon muris Balfour, 1905; Hepatozoon pernictosum 

 Miller, 1908. 



H, muris is found in the mononuclear leucocytes of Epimys norvegicus in 

 Khartoum, and in white rats in Washington, D.C. Its schizogony and 

 sporogony in Lelaps echidninus have already been described (p. 479). It 

 caused anaemia, severe illness, and death in the rats. 



Haemogregarina canis James, 1905. 

 Synonym, — Leucocytozoon canis James, 1905. 



Hcemogregarina canis was discovered by Bentley in the blood of a pariah dog, 

 Canis familiaris, in Assam, and this discovery was fully confirmed by James 

 in 1905. Christophers was the first investigator to trace out its full life- 

 history in 1906-07. 



It appears to be common in pariah dogs in Assam and Madras, but more 

 particularly in the puppies and less common in the adults. It is also found 

 in Ceylon, and, according to Dutton, Todd, and Tobey, it probably occurs in 

 dogs in the Gambia. 



Morphology. — The parasite is seen in the white corpuscle of the peripheral 

 blood as an oval, unpigmented mass which is difficult to stain, and which lies 

 in two envelopes — an outer formed from the cytoplasm of the corpuscle, and 

 an inner formed by itself. The cell in which it lies is not typical of any 

 corpuscle, though at first sight it resembles a polymorphonuclear leucocyte. 

 When stained, it is seen to possess a nucleus in the shape of a mass of chromatin 

 stretching across the body at one end. 



Schizogony. — Schizogony appears to take place only in the bone-marrow, 

 and has not been seen in the liver or spleen. It begins by the parasite gathering 



