PATHOGENIC PROTOZOA OF THE INFUSORIA 475 



Cilia cover the surface. The two nuclei and two contracted 

 vacuoles may commonly be made out. An excretory apparatus 

 is evidenced by the extrusion of waste material at a definite point 

 in the cell surface. The life-history is relatively complex. The 

 cell commonly multiplies by direct division. Conjugation and 

 encystment may occur. 



The Balantidium coli appears to be a common inhabitant of 

 the intestinal tract of swine. A large number of instances are 

 recorded in which it has been found associated in man with a 

 severe and even fatal type of diarrhea. The connection of this 

 organism with the disease as a causal agent rather than as a com- 

 mensal seems to be well authenticated. It appears that infection 

 may follow the ingestion of the cysts produced by the organism. 

 The disease has been reported from Europe, the United States, and 

 the Philippines. 



