CHAPTER LVII 



CLASS IV INFUSOEIA 

 SUB-CLASS (CILIATA) 



THIS class is sharply distinguished from all other protozoa by the 

 presence of numerous cilia, distributed in various ways over the 

 ectoplasm, which serve as organs of locomotion, and by the presence 

 of two or more nuclei. They fall into two classes, the ciliata, which 

 are provided with cilia during the entire life cycle, and the suctoria, 

 which lose their cilia on entering the adult stage; -the latter are of 

 no interest, since none are holozoic. 



Only one of the ciliates is of importance in medicine, Balantidium 

 coli. Balantidium minutum and Nyctotherus fa~ba, having been 

 reported only once in man by Schaudinn, are too rare to be con- 

 sidered here. 



BALANTIDIUM COLI (Malstan) 



This parasite, first described in 1857, is commonly found in the 

 lower intestinal tract of swine ; while usually harmless, it may cause 

 a moderate mortality in them from subacute and chronic dysentery. 

 It has frequently been reported as present in man, and is readily 

 diagnosed on examination of the stools. 



The organism is much like paramecium and is actively motile when 

 obtained from fresh stools, or from scrapings from the ulcerated 

 cecum at autopsy. The body is ovoid and rather stumpy toward the 

 anterior end, distinguished by the triangular peristome; average 

 measurements are about eighty by sixty microns. The ectoplasm is 

 covered with thick, parallel bands of active cilia, giving the animal 

 a striated appearance; the macronucleus is kidney shaped and lying 

 close to it the micronucleus may usually be distinguished. At one 

 side of the organism are found two contractile vacuoles, and, in the 

 endoplasm, food vacuoles and fat droplets. 



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