PRIMARY FUNCTIONS OF THE ORGANISM 35 



somewhat heavier and are employed to force food 

 particles into the so-called gullet to a point where 

 they are ingested. Thus, in comparison with Amoeba, 

 localization is found not only in the function of 

 locomotion, but also in that of ingestion. 



In a relative of Paramecium, Stylonychia (see 

 fig. 13), the cilia are themselves differentiated in 

 various regions of the body for different functions. 



FIG. 13. Stylonychia creeping on its oral ("lower") surface viewed 

 from the left side: 1, anterior cirri ; 2, adoral zone of. membranelles ; 

 3, anterior branch of the pulsating vacuole (4) ; 5, dorsal cilia ; 6, pos- 

 terior branch ; 7, caudal cirri ; 8, posterior cirri ; 9, ventral cirri. 

 (From Lang, after Biitschli and Schewiakoff.) 



Although those on the upper side have almost disap- 

 peared, yet Stylonychia is more active and has a 

 greater variety of movement than Paramecium. 

 This is due to the fact that the cilia on the lower side 

 of the cell-body are fused together in places to form 

 stout, elastic, hooklike " cirri," shaped and inserted 

 in such a variety of ways as to enable Stylonychia 

 to crawl and jump. Rows of ordinary cilia enable 

 it to swim. In addition to these forms of cilia, there 

 occurs in the oral groove a series of platelike mem- 



