108 



PROTOZOOLOGY 



of the Phytomastigina. A similar relationship seems to exist between 

 Paramecium bursaria, Stentor pohjmorphus, etc. and zoochlorellae; 

 Paraeuplotes tortugensis and a zooxanthella and others (p. 29). 

 Pringsheim (1928) showed that organic matters from zoochlorellae 

 are passed on to their host, Paramecium bursaria, to be used as food. 

 Through studies of relationships between zooxanthellae and in- 

 vertebrates, Yonge observed that the zooxanthellae utilize carbon 

 dioxide, nitrogen and phosphorus which are the catabolic products 

 of the host and supply in return oxygen, fats and carbohydrates to 

 the host. Photosynthesis in Phytomastigina (Hutner and Provasoli, 

 1951). 



Saprozoic (saprophytic) nutrition. In this nutrition, the Protozoa 

 obtain nourishment by diffusion through the body surface. This is 

 accomplished without any special organellae. Perhaps the only in- 



Fig. 38. Outline sketches showing the defecation process in 

 Spirostomum ambiguum (Blattner). 



stance in which the saprozoic nutrition is accomplished through a 

 special organella is the pusules (Figs. 127, 129) in marine dinoflagel- 

 lates which, according to Kofoid and Swezy (1921), appear to con- 

 tain decomposed organic matter and aid the organisms in carrying 

 on this process. 



The dissolved food matters are simpler compounds which originate 

 in animal or vegetable matter due to the decomposing activities of 

 bacterial organisms. Numerous free-living flagellates nourish them- 

 selves with this method. Recently a number of investigators found 

 that saprozoic Protozoa could be cultivated in bacteria-free media 

 of known compositions. For example, Pringsheim (1937) observed in 

 Polytoma uvella (Fig. 113, h) that sodium acetate is needed from 

 which the starch among others is produced and carbohydrates have 

 no direct bearing upon the nutrition, but fatty acids derived from 

 them participate in the metabolism. 



The Protozoa which live within the body of another organism are 



