264 THE BIOLOGY OF STENTOR 



were covered with ice and developed an oxygen deficiency these 

 reserves disappeared as the abundance of fat droplets increased. 

 This alternation of reserve stuffs suggested correlations with 

 temperature and oxygen tension, as well as the possibility that the 

 carbohydrate was converted into fats. Zingher (1933) in fact 

 maintained that both starches and proteins are convertible into 

 fats by ciliates. 



Fig. 73. Nutritional reserves in S. coeruleus. 



A. Photo showing location of glycogenoid carbohydrate 



granules (cf. Fig. 17A). 



B. Random distribution of fat droplets revealed by Sudan III 



staining. (After Zingher, 1933.) 



In laboratory tests, Zhinkin found maximum increase in number 

 and size of glycogenoid granules at 3-5 °C, while the primary con- 

 dition for fat accumulation was lack of oxygen. In general it appears 

 from his data that, naturally, an accumulation of nutrient reserves 

 requires a temperature which is not so low that metabolism is 

 sharply curtailed nor so high that increased activity in cell multipli- 

 cation utilizes the food directly and may even draw upon reserves 

 already present. Weisz found that fat stores were not used in 

 regeneration, and Zingher considered them necessary to a normal 

 condition of the cytoplasm. My impression from long observation 

 of stentors in culture is that well-fed animals always have abundant 



