13 
are freely liberated in the midgut and in the body cavity large cysts 
are found; but, as a result of work on L. canis in the tick, I am doubt- 
ful whether the cysts have anything to do with the haemogregarine.” 
Patton ® has described a parasite in the large mononuclear leuco- 
cytes of palm squirrels. Forms measuring 10 micra in length were 
seen, one extremity being bent and somewhat pointed, resembling a 
tail. Free vermicules exhibited slow streaming^’ movements. Pat- 
ton made a number of leucocyte counts upon blood from infected 
and noninfected squirrels and found both a relative and numerical 
increase of the large mononuclears in the former. Smears were made 
from all the organs of the squirrel, but no evidence of multiplication 
was observed. 
Lice (a species of Hsematopinus) were found upon many of the 
squirrels examined. L"pon dissection active vermicules measuring 
15.5 micra were seen in the gut of the lice which had been placed 
upon infected squirrels. Xo further development was observed, nor 
were any parasitic bodies found m the ovaries or salivary glands. 
Christophers ^ has recently published his observations upon the 
sexual cycle of Leucocytozoon canis in the tick. He had previously 
described the schizogony, which takes place in the bone marrow, but 
never in the liver or kidney. The merozoites are formed in cysts. 
One cyst may contain 30 or more merozoites. 
The sexual cycle in the dog tick (RJiipiceplialus sanguineus) is 
described as follows: In the gut of ticks examined immediately after 
removal from infected dogs free vermicules are seen; after twenty- 
four hours they have penetrated the cells of the gut wall and are seen 
in various stages of fission, which precedes the formation of the sexual 
elements. On the third day conjugation bodies and the first stages of 
the development of the fertilized oocyst are seen. Mature oocysts 
are observed on the fourth day. According to Christophers, the ver- 
micules, after entering the intestinal cell, divide into two, four, or even 
eight vermicules. Two of these vermicules then conjugate and an 
oocyst is formed, winch, when fidly developed, measures 14 micra 
in diameter and splits up into 12 to 14 sporozoites, without an investing 
capsule. The entire process takes place in the epithelium of the gut 
wall and not in the coelomic cavity of the tick. 
From the description of Christophers it seems difficult to under- 
stand his interpretation of some of the stages observed. Especially 
it would seem difficult to distingiush the parasites formed by fission 
of the vermicules from the free sporozoites. He mentions no feature 
o Patton, W. S.: On a parasite found in the white corpuscles of the blood of palm 
scpiiiTels. Sci. Mem. Officers Med. & San. Dept. Govt. India, 1906, n. s., no. 24. 
& Christophers, S. R.: The sexual cycle of Leucocytozoon canis in the tick. Sci. 
4Iem. Officers Med. & San. Dept. Go\i:. India, 1907, no. 28. 
