SPIROTRICHA, HETEROTRICHA 



805 



N. cordiformis (Ehrenberg) (Figs. 85; 344, c). 60-200m by 40-140^; 

 ovoid; micronucleus behind macronucleus; no karyophore; in the 

 colon of frogs and toads. Higgins (1929) notes that there are certain 

 differences between American and European forms and that the 



Fig. 344. a, b, Nydotherus ovalis, X340 (Kudo); c, N. cordiformis 

 X 170 (Stein) ; d, Condylostoma vorticella, X 120 (Penard) ; e, Stentor coerul- 

 eus, somewhat contracted, X70 (Roux); f, S. polymorphus, X60 (Roux); 

 g, S. mulleri, X50 (Kahl); h, S. roeseli, X75 (Roux); i, S. igneus, X160 

 (Kahl); j, S. amethystinus, X100 (Kahl). 



