390 
Philippine Journal of Science 
1919 
or rudimentary eytopharynx. 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 subphyium 
Infusoria; class Ciliata; order Heterotrichida ; suborder Poly- 
trichina ; and family Bursaridse. 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 p to 635 p. 
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 p 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 eytopharynx. 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 p to 100 p in length and 50 p 
to 70 p 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 
