34 



GENERAL BIOLOGY 



ization, in each one 

 of which, compared 

 with Amoeba proteus, 

 there has been 

 brought about a 

 very much greater 

 efficiency in move- 

 ment through a con- 

 centration of effort 

 and the localiza- 

 tion of the organ 

 of locomotion. 



In another group 

 of the Protozoa, not 

 only the function of 

 movement, but also 

 that of ingestion has 

 become more or less 

 specialized. In the 

 Ciliates, of which 

 Paramecium is a 

 typical though not 

 the most generalized 

 example, the animal 

 swims rapidly by 

 means of bristle-like 

 cilia developed all 

 over the cell-bod^, 



These are practically all alike, and consequently the 

 movements of the animal are very uniform and cir- 

 cumscribed. The cilia along the oral groove are 



FIG. 12. Paramecium viewed from 

 the oral surface : L, left side ; R, right 

 side; an, excretory area ("anus"); ec, 

 ectosarc ; f.v., food vacuoles ; g, gullet ; 

 m, mouth ; ma, macronucleus ; mi, micro- 

 nucleus ; o.g., oral 'groove ; p, cuticle ; tr., 

 trichocyst layer. (From Jennings.) 



