266 THE BIOLOGY OF STENTOR 



fore tends to form the respiratory system of a whole, even in a 

 diminished amount of cytoplasm. 



Yet it is interesting that when de Terra (1959) forced all the 

 macronucleus into one daughter cell during division and so pro- 

 duced coeruleus with twice the normal macronuclear complement, 

 the uptake and incorporation of radiophosphorus was not different 

 from that of normal cells. 



As relating to energy metabolism, sites of acid phosphatase in 

 coeruleus were determined by Weisz (1949b). Positive tests were 

 obtained around macronuclear nodes and other bodies in the 

 endoplasm as well as at the basal granules of membranelles and 

 body cilia. Enzyme activity decreased during starvation but not 

 during periods of morphogenesis, and appeared in oral primordia 

 only after cilia were present and active. Therefore, acid phosphatase 

 is probably involved in the action but not in the development of 

 ciHa. 



4. Digestion 



In Folliculina and Stentor the transit of the food vacuoles is not 

 in a definite track provided by cyclosis of the endoplasm, as in 

 Paramecium, but each is individually handled, according to 

 Andrews (1955). Schwartz (1935) described the normal digestion 

 of Colpidium by coeruleus, which required about 20 hours and 

 included dissolution of the nucleus of the prey. In feeding 

 enucleates, however, the food vacuoles from the start contained 

 excess fluid and at no time was digestion normal or complete. It 

 will also be recalled that Schwartz found indication that even a 

 substantial reduction in number of macronuclear nodes resulted 

 in abnormal metabolism with inadequate digestion. 



Meissner (1888) reported that stentors (apparently ^ofymorpAw^) 

 take up and digest starch grains. This was confirmed by Zingher 

 (1933) who also noted increased fat droplets following the starch 

 meal, suggesting that carbohydrates are converted into fats; yet 

 coeruleus predominantly rejected starch grains in the feeding 

 studies of Schaeffer (see p. 11). Contrary to Meissner, Zingher 

 found that coeruleus ingests the fat droplets of milk, which he 

 thought were assimilated directly because rapid cell multiplication 

 followed. In rich cultures with little oxygen, digestion was inhibited 

 and stentors became stuffed with undigested food vacuoles. 



