480 



BIOLOOY OF THE PROTOZOA 



the majority of cases the mouth leads into a ciliated gullet. Such 

 constant feeders are limited to a bacterial diet and other minute 

 food substances while the gymnostomes, by reason of the disten- 

 sibility of the oral region are able to take in living organisms even 

 larger than themselves (see p. 186 and Fig. 98). 



C 



£> 



Fig. IDS. — Tentacles of Infusoria. .1, Mesodinium pulex, with four oral tentacles 

 for adhering; B, Podophrya fixa; C, I), tentacles of Ephelotidae. (A, C, D, from Cal- 

 kins; B, original.) 



In Suctoria, food-taking is of an entirely different type. Mouths 

 are absent but food may be taken in through any one of the many 

 suctorial tentacles. The body wall of a captive organism is cyto- 

 lyzed at the point where the tentacle is in contact and the endoplasm 

 of the prey either passes in a stream through the lumen of the 

 tentacle, or the endoplasm of the captor enters the body of the 



