PARASITOLOGY. 203 
trypanosomes and is about twenty-five microns long 
and one and one-half microns broad. 
Animals Infested —Rats. 
Part Infested —The blood. 
Condition Produced.—The mode of infection is sup- 
posed to be by means of lice and fleas. The rats 
suffer no inconvenience from this infestation, and 
therefore it must be considered non-pathogenic for 
this animal. 
SPOROZOA (Spore; zodn—animal). 
The class Sporozoa includes a group of single- 
celled microdrganisms provided with a protoplasmic 
cell body in which is found a nucleus. It is pro- 
vided with a limiting membrane. The method of re- 
production is by the formation of spore corpuscles, 
or the division of the nucleus and protoplasm into 
several parts. Three orders of this class interest 
us, viz., Coccidia, Sarcosporidia and Hemasporidia. 
Coccipi1um OvirorRME (Coccum—a kernel). 
Synonym.—Psorospermia oviforme. Eimeria stie- 
dae. 
Distribution—Found in the United States and 
Europe. 
Description—A _ single-celled animal organism, 
ovoid in shape, and forty to fifty microns long by 
twenty-two to twenty-eight microns thick. It is pro- 
vided with a double limiting membrane. The nu- 
cleus is three times as large as that of an epithelial 
cell; it readily stains with hematoxylin. 
Life Cycle—From the protoplasm of the adult 
Coccidium there is developed small, rounded, nucle- 
ated masses (the spores). At first the diameter 
measures from nine to ten microns; this pody grows 
