EUGLENA 31 



B. Life Processes of Euglena 

 1. Nutrition 



Possessing chlorophyll, Euglena is able to manufacture photo- 

 synthetically the complex foodstuffs necessary for the maintenance 

 of life, just as is the case in the chlorophyll-bearing plant cell. It 

 has also been shown that Euglena, when placed in an environment 

 containing organic materials in solution, can nourish itself and 

 thrive in the absence of sunlight. It is apparent in the latter con- 

 dition that Euglena is able to make use of another type of nutrition, 

 known as saprophytic or saprozoic — the exact term depending 

 upon whether the organism is regarded as a plant or an animal — 

 in which complex food materials in solution are taken through the 

 cell wall by diffusion and assimilated. 



There does not appear to be any evidence that Euglena ever 

 receives any nutriment by the holozoic method of nutrition, such 

 as was studied in Amoeba, in which solid particles of food are in- 

 gested and then acted upon by digestive ferments in order to render 

 them soluble and capable of being assimilated. 



2. Respiration and Excretion 



It has been emphasized previously that the process of respira- 

 tion is continuous in living organisms. There is no other way for 

 them to secure the energy necessary to maintain vital processes. 

 Respiration, however, may be obscured in an organism in which 

 photosynthesis is occurring. Thus in daylight the chlorophyll in 

 Euglena undoubtedly uses all the carbon dioxide produced by 

 the katabolic processes in the cell and also takes in some additional 

 from the environment, at the same time releasing the excess free 

 oxygen formed by the photosynthetic processes. In the dark 

 when photosynthesis stops, Euglena will necessarily give off the 

 carbon dioxide and take in oxygen, just as in a typical animal 

 cell like Amoeba. The elimination of the nitrogenous wastes from 

 Euglena apparently occurs through the contractile vacuole ap- 

 paratus and at the surface, as in Amoeba. 



3. Reproduction 



Under favorable environmental conditions, when a Euglena 

 has reached a certain volume, reproduction by binary fission 

 occurs, as noted in Amoeba, and two daughter cells result. The 



