METABOLISM 265 



carbyhodrate reserves and probably fat stores as well. Only with 

 considerable trouble could coeruleus be divested of its glycogenoid 

 granules (Tartar, 1959a). The seasonal cycle which Zhinkin seems 

 to have well documented may therefore be the consequence of a 

 delicate and changing equilibrium between rates of feeding and 

 cell growth. 



3. Respiration 



The oxygen requirements of Stentor have been little studied. 

 Stolte (1922) remarked that decreased oxygen produced vacuoliza- 

 tion of the endoplasm. In a Russian ecological study which I 

 have not seen, Zhinkin and Obraztsov (1930) observed that 

 polymorphus and coeruleus are found in ponds only where there is 

 abundant oxygen : under ice, only where bottom springs provided 

 enough of the dissolved gas. Sampling of an Iowa pond showed 

 stentors to be abundant only near the bottom under nearly 

 anaerobic conditions according to Sprugel (1951), a result most 

 paradoxical since the same animals lived well when transferred to 

 jars in the laboratory. Oxidation-reduction studied by means of 

 color indicators in protozoa, presumably including Stentor, was 

 pursued by Roskin and Semenov (1933) in a study which was 

 not available to me. It has been observed (Whiteley, personal 

 communication) that in some races oi coeruleus the animals remained 

 near the bottom while in other clones they always collected near 

 the surface, suggesting that there may be racial differences in 

 oxygen requirement. 



Using the Cartesian diver technique, Whiteley (1956) discovered 

 a marked and unique increase in respiratory rate in halves of 

 starved coeruleus containing all the macronucleus and hence having 

 abnormally high ratios of nucleus to cytoplasm. During the first 

 day the rate of respiration showed increases of as much as 175%. 

 This acceleration was correlated solely with the nucleo-cytoplasmic 

 ratio and was repeated after a second removal of cytoplasm. 

 Appropriate controls demonstrated that neither cutting nor 

 regeneration were responsible for the increase. Enucleates showed 

 a low and gradually decreasing rate of respiration ; that of whole 

 animals, high and also only decreasing. In the critical macro- 

 nucleate halves the accelerated respiration temporarily approached 

 the values shown by whole cells. The whole macronucleus there- 



