THE BELL-ANIMALCULE. 



173 





mac 



Fio. 90. A single head of Vortlcella, highly magnified, ex, contractile axis of the 

 stalk; c, cuticle; c.u, contractile vacuole; d, disk; et, ectoplasm; en, entoplasm; 

 ep, epistome; f.v, food-vac uole ; m, mouth; mac, macronucleus ; mic, micronu- 

 cleus ; ce, oesophagus ; p, peristome ; r, vestibule ; w.i\ water- vacuoles ; a;, point at 

 which epistome and peristome meet at one end of the vestibule. 



