34 



IN VERTEBRA TE MOKPHOLOG T. 



bristles upon which the animal creeps (Hypotrichous forms, 

 Fig. 17, D}. 



A definitely localized mouth-opening is always present, 

 situated frequently at the extremity of a peristomial groove 

 and leading into a gullet of variable extent, usually lined by 

 cilia, though sometimes furnished with a chitiuous support 



CF.- 



FIG. 17. A, Paramcecium ; B, Stentor ; C, Vorticella ; D, Euplotes. 



cv = contractile vacuole. n -- nucleus. 



m = mouth. n' micron ucleus. 



my = myopkatie. tr = trichocyst. 



(Chilodon). There is, however, no special digestive tract, the 

 food-particles after traversing the gullet being received into 

 the body-protoplasm, where they are digested. Usually there 

 is a localized cgestive region, and in a few cases there is a 

 definite anal opening. The food is procured as in the Flag- 

 ellates by the currents set up in the water by the cilia carry- 



