SPIROTRICHA, HETEROTRICHA 



575 



adoral zone distinct; macronucleus sausage-form; 1-2 contractile 

 vacuoles; cytopyge terminal; food vacuoles with red blood cor- 

 puscles, leucocytes, etc.; cysts 50-60/x long; in colon of man, pigs, 

 and chimpanzees. The infection in man is presumably acquired 



Fig. 261. a, Bursaria truncatella, X60 (Kahl); b, Thylacidium trun- 

 catum, X440 (Schewiakoff ) ; c, Bursaridiwm dijficile, X210 (Kahl); 

 d, e, Balantidium coli, X540 (Kudo); f, B. duodeni, Xl70 (Stein); 

 g, B. praenudeatum, X950 (Kudo and Meglitsch). 



through cysts from pigs in which the organism is, as a rule, quite 

 common and is responsible for the balantidiosis in unfortunate 

 patients; widely distributed. 



B. suis McDonald. Ellipsoid; 35-120;u by 20-60ju; macronu- 



