THE INFUSORIA 



183 



having the function of transmission of impulses within such pro- 

 tozoan cells, they constitute a mechanism by which coordinated 

 action of parts of the cell may be accomphshed. The function of 

 such a mechanism may be compared with that of the nervous 



fi 



Fig. 98.— Neuromotor mechanism of Paramcecium caudatum. 

 A, showing fibers radiating from motorium im); B, showing fibers connected with 

 cilia and trichocysts; C, showing lesser centers of coordination in region of cytopharynx. 

 CAfter Rees, University of California Publications, 1922.) 



system in a multicellular animal. Since it hes within the limits 

 of a single cell, its structure cannot be so compared; unless one is 

 more impressed by the Organismal Theory (c/. p. 194) than by the 

 Cell Theory in making comparisons between single-celled and 

 many-celled animals. 



Metabolic Processes. — In feeding, the cilia of paramcecium 

 draw a current of water against the buccal region (Fig. 95 C), 

 and thus masses of fine particles, such as bacteria, smaller protozoa, 

 and organic debris, w^hich constitute the food, are passed through 

 the mouth into the gullet. By means of the undulating membrane 

 and by a gulping movement of the protoplasm, such masses of food 

 are passed into the endoplasm, included in a drop of water, and 

 are ingested. Within the endoplasm these food vacuoles move 



