No. 603] 



ECOLOGY OF THE PROTOZOA 



165 



Other forms present in less numbers (few or rare) 



The nucleus of Cercomonas crassicauda (Fig 9) is 

 located near the functional anterior end of the body, and 

 is not easily seen. The anterior flagellum is likewise diffi- 

 cult to distinguish, even upon staining, being exceedingly 

 filamentous. It seems to have little to do with locomotion,, 

 and I believe that it is used principally as a sort of an- 

 tenna. The propulsion of the creature is apparently 

 accomplished by the lashings of the stout posterior fla- 

 gellum, no matter which end of the organism is directed 

 forward. 



Cercomonas termo (Fig. 10), from 5 to 15 microns, is 

 extremely variable in shape in the adult form. Its com- 

 monest and therefore characteristic appearance is roughly 

 heart shaped, the flagellum arising from the broader ex- 

 tremity of the body. The young are not so variable, but 

 although constant in general form, confusingly resemble 

 the monads, in particular Monas irregularis. Their mi- 

 nuteness (.5 to 2 microns) makes them difficult to identify. 

 They should be stained with a very weak solution of iodine 

 or acetic methyl green, since the stronger stains, used for 

 the larger Protozoa, cause them to lose their character- 

 istic outline and to disintegrate in a short time. 



Environmental Type No. Ill : Clear Flowing Water 

 WITH Abundant Plant Life 

 Clear springs and streams supporting vigorous growths 

 of such algae as Spirogyra, Drapernaldia, etc., and water 

 cresses; bottoms covered with Diatoms (often chiefly 

 Meridion circulare), Desmids, and Oscillatoria. Tem- 

 perature of water, cir. 66° F. 

 Predominant forms : 



Amoeba proteus, abundant Chilomonas paramcech 



Amoeba proteus, flagellospores (f), Colpidium sp.. several 



Chlamydomonas 

 Colpidium sp. 



'icauda 



sp. 



