11 
cytes affected are of the polymorphonuclear variety. The nucleus 
in 86 per cent of the parasites is situated near one extremity and is 
oval or round in shape, and stains like the nuclei of the leucocytes. 
The manner in which nonsexual multiplication takes place in the 
bone marrow is described by Christophers.® 
Since the discovery of Leucocytozoon canis by Bentley a number of 
somewhat similar parasites have been observed in the blood of mam- 
mals, all in tropical regions. In some instances they affect only the 
Avhite corpuscles, in others only the red cells, but never both. Certain 
peculiarities and their similarity to hsemogregarines in cold-blooded 
animals are sufhcient to identify them in the Haemogregarinidse. 
In 1905 Balfour^ described a new parasite in the red blood cells 
of Jaculus jaculus, the jerboa, or kangaroo rat, of Sudan. This 
organism, according to Laver an, is a haemogregarine. 
The trophozoite, which is either free or lies in the remains of a red 
blood cell, is sausage shaped, nonpigmented, and nonmotile. It 
measures 5.5 to 7 micra in length and from 1.4 to 2.8 micra in breadth. 
AVhen stained by the Leishmann-Romanowsky method, the nucleus 
is large, oval, and centrally located. In the peripheral blood all 
forms are in about the same stage of development. The animal host 
does not suffer in health. 
The parasite {Haemogregarina halfouri) of the jerboa is bent slightly 
upon itself and its length is a little greater than that of the red cor- 
puscles. In addition to the form described, Balfour observed on one 
occasion a free motile vermicule form without flagellum. In a stained 
specimen which showed this stage the total length was 15.5 micra, one 
extremity being finely tapered to a point, the other rounded and con- 
taining chromatin granules. Multiplication occurs by schizogom’". 
The schizonts are found in the liver, kidney, and bone marrow, in 
the form of cysts. The cyst walls appear to be formed of the rem- 
nant of the cell of the organ invaded. In the liver the schizonts 
appear quite similar to those of certain coccidia. The manner of 
invasion of the liver cells has not been determined. No sexual cycle 
or mode of transmission is known. Balfour states that no naked-eye 
indications of disease are present in an mfected animal. The spleen 
is not enlarged. He also mentions the fact that he has discovered 
what seems to be the same parasite (H. halfouri) in the mononuclear 
leucocytes of a rat {Mus decumanus) in Kdiartoum. 
In 1905 Christophers discovered a parasite in the red blood cells 
“ Christophers, S, R.; Leucocytozoon canis. Sci. Mem. Othcers Med. & San. Dept. 
Govt. India, 1906, n. s., no. 26. 
^ Balfour, A.; A hsemogregarine of mammals. Journ. Trop. Med., vol. 8, 1905, 
p. 241; vol. 9, 1906, pp. 81-84. 
c Christophers, S. R.; Hsemogregarina gerhilli. Sci. Mem. Officers Med. & San. 
Dept. Gov. India, 1905, n. s., no. 18.- 
