79S 



PROTOZOOLOGY 



B. truncatella M. (Fig. 340, a). 500-1000 m long; macronucleus a 

 long rod; 10-34 vesicular micronuclei; fission mostly during night; 

 feeds on various Protozoa; cysts 120-200^ in diameter; macronu- 

 cleus becomes coiled and intertwined; fresh water (Schmahl, 1926; 

 Beers, 1948). 



Genus Thylacidium Schewiakoff. Similar to Bursaria in general 

 appearance; but smaller in size; peristome simple in structure with- 

 out longitudinal fold; with zoochlorellae; fresh water. One species. 



T. truncatum S. (Fig. 340, b). 60-100/x long. 



Genus Bursaridium Lauterborn. Similar to Bursaria; peristome 

 funnel turns to right ; fresh water. 



B. difficile Kahl (Fig. 340, c). Anterior end truncate, cyto pharynx 

 slanting toward right; about 130ju long. 



Fig. 341. Balantidium coli, X530 (Kudo), a, a living trophozoite; b, a 

 stained trophozoite; c, a fresh cyst; d, a stained cyst. 



Genus Balantidium Claparede and Lachmann (Balantidiopsis 

 Butschli; Balantiodoides Alexeieff). Oval, ellipsoid to subcylindrical; 

 peristome begins at or near anterior end; cytopharynx not well de- 

 veloped; longitudinal ciliation uniform; macronucleus elongated; a 

 micro nucleus; contractile vacuole and cytopyge terminal; in the gut 

 of vertebrates and invertebrates. Numerous species (Hegner, 1934; 

 Kudo and Meglitsch, 1938). 



B. coli (Malmsten) (Fig. 341). Ovoid; 40-80/x by 30-60m, but 

 length varies 30-150/z; body covered by many slightly obliquely 

 longitudinal rows of cilia; peristome small near anterior tip, lined 

 with coarser cilia; inconspicuous cytostome and cytopharynx are 

 located at the end of peristome; 2 contractile vacuoles, one terminal, 

 the other near the middle of body; macronucleus sausage-shape 

 and a vesicular micro nucleus; cytopyge near the posterior tip; food 

 particles are of various kinds, including erythrocytes and other host 



