THE INFUSORIA 



173 



A. PROTOPLASMIC STRUCTURE 



As in all other Protozoa, the endoplasm consists of alveoli of vary- 

 ing size and arrangement, the network being built up of plasm of 

 greater or less density. Within the endoplasm there is a constant 

 streaming of the granules, which varies greatly in the different species 

 and even in the same individual under different conditions. In some 



Fig. gi. Dileptus anser O. F. M. [BUTSCHLI.] 

 m, mouth ; N, macronucleus ; /, trichocysts on the tentacle-like end. 



cases the course of the streaming recalls cyclosis in some plant-cells, 

 and frequently follows a well-defined and unvarying route (Colpoda 

 cucullus, or Paramceciiim bursaria). In all cases the current seems 

 to start from the mouth, passing backward around the cell either to 

 the right or left, then forward and back to the mouth (Biitschli). 

 In this stream, circulating through the body of the animal, are 



