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; zoon— animal) . 



The class Sporozoa includes a group of single- 

 celled microorganisms provided with a protoplasmic 

 cell body in wdiich 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. 



CocciDiUM OviFORME (Coccum — a kernel). 



Synonym. — Psorospermia ovi forme. 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 body grows 



