12 
of the Indian field rat {Gerhillus indicus) wliich resembles H. halfouri. 
The affected corpuscles (somewhat enlarged) contained a minute 
motionless vermicide with a short, sharply flexed tail (trophozoite). 
A distinct space surrounded the parasite. In some fresh prepara- 
tions there were free parasites similar to the above, except that the 
pointed extremity was no longer bent. They exhibited active gliding 
movements, also twisting and turnmg motions. In stained speci- 
mens the trophozoites were in the red cells and appeared to be envel- 
oped by a capsule. A large chromatin, body was situated in the 
“‘tail” of the parasite, also occasional scattered granules. 
Xo certain sexual differentiation of the trophozoites could be made 
out. Although all the organs of infected rats were carefully studied, 
no evidence of nonsexual multiplication could be found. Infected 
rats showed no constitutional disturbances. Differential leucocyte 
counts indicated that the percentage of different kinds of leucocytes 
differed but little from the normal. 
The only ecto-parasites found upon the rats were insects — a new 
species of louse (Hsematopinus) measuring 1.4 by .5 mm. Gertam 
structures were encountered in the dissection of these lice which 
Christophers regarded as phases of the sexual c}xle of Tl. gerhilli. 
Although experiments were made to infect lice from infected animals, 
no recorded attempts were made to transmit the infection from one 
animal to another by means of lice. In his experiments a number 
of lice were placed upon a young heavily infected rat. These were 
removed at stated intervals and examined. On the fourth day two 
lice were removed and examined. In the midgut and intestine vermi- 
cides in active motion were observed. On the seventh day large 
cysts were observed lying free in the body cavity of the insect. They 
were of large size, measuring as much as 350 inicra in diameter. 
When dissected out they appeared as minute white spheres which, 
with the microscope, were observed to be filled with minute cysts 
containing six or eight crescentic bodies. Younger cysts measuring 
10 micra in diameter were also seen, also intermediate ones varying 
in size between the smallest and the largest. Xo satisfactory stained 
specimens of these intermediate stages were obtained. Xo abnormal 
appearance was observed in the salivary glands of any of the lice 
examined. When ruptured cysts vrere mixed with the blood of the 
Indian rat and examined with the microscope, the crescents became 
active vermicules. 
Xo forms suggesting sexual elements or conjugation were observed 
by Christophers. In a recent work this writer" states, regarding 
the life cycle of H. gerhilli in Hsematopinus stephensi: “Vermicules 
“ Chi’istophers, S. R.: The sexual cycle of Leucocytozoon canis in the tick. Sci. 
Mem. Officers Med. & San. Dept. Govt. India, 1907, no. 28. 
