OF THE ALIMENTARY TRACT 203 



tivity, being more conspicuous in diarrhoea or dysen- 

 tery. The cyst is not always present, even in the 

 natural stool. 



Both are subject to ready observation and identi- 

 fication in fresh unstained preparation, the structural 

 detail being subject to complete study only in well 

 stained specimens, such as from the iron-haematoxy- 

 lon staining. 



The inexperienced should have no difficulty in 

 recognizing it in stool examination; a knowledge of 

 the existence of such an organism, a picture of it, 

 and observation of it in fresh stool, should be all that 

 is necessary. One should beware, however, of the 

 common occurrence of similar free living forms which 

 may occur in stale stools or in stagnant solutions. 



HABITAT AND EFFECTS 



Balantidium coli occurs as a parasite of the colon 

 of man, after it has hatched from ingested cysts. Its 

 activity is mainly in the caecum and it naturally en- 

 cysts as it passes down the intestine. It may be seen 

 active in any part, however, of the colon. 



The behavior of the organism and its effects upon 

 the host are not unlike the case of Endamoeba histo- 

 lytica. It is a parasite therefore of considerable in- 

 terest in medicine, and balantidiosis of the intes- 

 tine of man has a significance akin to intestinal 

 amoebiasis. In fact the different phases of intestinal 

 amoebiasis have their counterparts in intestinal bal- 



