46 
the blood stream, and are carried to the liver. They penetrate the 
liver cells and undergo schizogony. The nuclei of the oval schizonts 
are arranged at the poles and an enveloping cyst is developed. Each 
nucleus becomes the basis of a merozoite, of which an average of 16 
are formed, arranged at the poles. The ripe cyst measures 25 by 30 
micra. Later the cyst wall becomes softened and is ruptured. The 
merozoites are set free as actively moving vermicules, indistinguish- 
able from those developed from the sporozoites. Some of the mero- 
zoites enter fresh hver cells and repeat the schizogony. Other mero- 
zoites enter the blood streams as vermicules, are taken in by the large 
mononuclear lymphocytes, and develop a definite enveloping cyst 
wall. A few vermicules may escape the action of the leucocytes and 
appear in the blood stream. 
Ix THE Mite. 
When the blood of an infected rat is swallowed by a mite the 
encysted trophozoites are set free in the stomach by solution of the 
cyst as free vermicules. Two similar vermicules become associated 
and conjugate. One, the macrogamete, grows larger and partly sur- 
rounds the other, the nficrogamete. The protoplasm becomes fused 
and later the nuclei conjugate and fuse to form a zygote. The zygote 
becomes a sluggishly motile ookinet, which penetrates the stomach wall 
of the mite and enters the body tissues and becomes encysted (oocyst). 
Here a remarkable enlargement of the karyosome takes place. The 
parasite increases enormously in size. The nucleus of the spherical 
sporont thus formed undergoes division into many daughter nuclei, 
which migrate to the surface of the sporont. The surface of the latter 
becomes mammillated. The projections, each of which contains a 
nucleus, increase m size and length: later they are broken off and 
each becomes a sporoblast. The nucleus of the sporoblast undergoes 
division, the resulting nuclei being arranged at the poles. The sporo- 
blast increases in size and a cyst wall develops. Around each nucleus 
a sporozoite is formed. In the ripe sporocyst, which measures 25 by 
30 micra, the sporozoites, 16 in number (average), are arranged at the 
poles. The large cyst (oocyst) contains from 50 to 100 of such sporo- 
cysts. Alien the mite is.swaUowed by a rat the cycle is repeated. 
It is recognized that the haemogregarines Leucocytozoon canis and 
Leucocytozoon funamhuli, which have already been described, in India 
are more or less similar to Hepatozoon perniciosum; but as the genus 
Leucocytozoon has already been taken by a blood parasite, L. ziemanni, 
of an entirely different character, this generic name can not be prop- 
erly retained. 
The relation or possible identity of Leucocytozoon ratti, described 
by Adie, with H. perniciosum can only be cleared up when the life 
