390 Philippine Journal of Science m» 



or rudimentary cytopharynx. The peristome area bears an 

 adoral zone of membranelles which are continuous with a line 

 of slender, delicate cilia or membranelles which line the gullet. 

 An anal aperture or cytopyge is usually present at the most 

 posterior point of the body. Contractile vacuoles are present 

 in varying numbers. The meganucleus is oval, bean-shaped, or 

 reniform. The organisms occur as entozoic parasites of verte- 

 brates and invertebrates. 



Systematically the genus Balantidium falls in the subphylum 

 Infusoria; class Ciliata; order Heterotrichida ; suborder Poly- 

 trichina ; and family Bursaridae. In this genus are included the 

 following species : 



Balantidium entozoon Ehrenberg. 



Found as an obligate parasite in the rectum of the common 

 frogs Rana temporaria and R. esculenta. It was first described 

 by Leeuwenhoek in 1722. It has an oval or pyriform body, 

 narrowed anteriorly. This narrow anterior end is somewhat 

 curved to one side and obliquely truncate. It is provided with 

 a peristome area which extends backward and continues into 

 a well-defined gullet. There are four contractile vacuoles. The 

 meganucleus is sausage-shaped. It measures 105 n to 635 /*. 



Balantidium elongatum Stein. 



Found as a parasite in the intestinal canal of Triton tseniatus 

 and Rana esculenta. It has a length of 212 p to 302 ft which is 

 two to two and one-half times its breadth. The body is "elongate- 

 fusiform, subcylindrical," tapering anteriorly. The peristome 

 area is slitlike, short, and lies in a medium position without 

 any distinct cytopharynx. There are usually two distinct 

 vacuoles. The meganucleus is oval in shape. 



Balantidium coli Malmsten. 



This species was discovered in the bowel discharges of two 

 patients suffering from chronic diarrhoea. The organism was 

 described by Malmsten under the designation Paramecium coli. 

 Stein later discovered the same species in the intestinal tract 

 of hogs. The body is oval, the anterior end being either broader 

 or more pointed, according to the degree of contraction of the 

 peristome area. It measures 60 M to 100 ,* in length and 50 p 

 to 70 /x in width. The peristome is triangular or funnel-shaped. 

 The pharynx is not very distinct. There are two contractile 

 vacuoles. There is a cytopyge that is postero-terminal. The 

 meganucleus is bean-shaped or reniform. The micronucleus is 



