PLATE 31 



Fig. 9. Incision anterior ot the anal cirri, cutting the anal cirri fibers. 

 X 800. a.c., anal cirrus; a.c.f., anal cirri fiber; ant. cyt. f. and mb.f., membranelle 

 fiber; c.v., contractile vacuole; f.c., frontal cirri; m.c., marginal cirri; mac., 

 macronucleus; m.f.p., membranelle fiber plate; mic., micronucleus; mot., motor- 

 ium; o.l., oral lip; ph., pharynx. 



Figs. 10, 11, and 12. Incisions not severing the anal cirri fibers or the mem- 

 branelle fiber. 



[466] 



