OF THE ALniEXTARY TRACT 197 



hairlike processes, called cilia, a prominent mouth, 

 contractile vacuoles, and two nuclei, the macronu- 

 cleus or meganucleus, the larger, having to do with 

 the somatic life of the organism, the micronucleus 

 concerned in germination. 



The cilia are set in the ectoplasm of the body, 

 through the surface, in rows. Their movement is 

 rythmical and reminds one of a grain field with wind 

 waves. Except those of the cytostome area they 

 are purely for the purpose of locomotion, serving to 

 propel the organism rapidly forward and at the same 

 time rotating it slowly, by means of the creation of 

 currents. 



The cilia in the depression around the cytostome 

 are longer and serve for food gathering and introduc- 

 tion into the mouth. 



The mouth or cytostome is conspicuous as a fun- 

 nel-like indentation in one surface, the ventral, and 

 from it food particles are carried into the endoplasm 

 through a short oesophagus. 



The ectoplasm is more dense than the endoplasm, 

 which is vacuolated, the vacuoles serving as stom- 

 achs for the digestion of bacteria and other food mate- 

 rials. 



The contractile vacuoles, seen only in this class 

 of alimentary tract protozoa, are present in many 

 free-living forms of protozoa. They pulsate ryth- 

 mically and are related to the circulation or metab- 

 olism of the organism. 



At the posterior end of the body is a small indenta- 



