302 THE BIOLOGY OF STENTOR 



membranelles can continue for about one week and is dramatic 

 evidence of the extent of energy metabolism which continues in 

 the absence of the nucleus. Very likely this is to be explained by 

 the presence of mitochondria or specialized ectoplasmic granules 

 as relatively independent centers of oxidative phosphorylation. 

 Normal avoiding responses and searching behavior seem to be 

 shown by enucleates; therefore, to repeat an apercu of doubtful 

 brilliance, the nucleus is not a brain. As the proof of the pudding 

 is in the eating, so a test of effective behavior lies in the feeding. 

 Prowazek (1904) found that enucleated coeruleus could ingest 

 chlorellae and Schwartz (1935) showed that some would take up 

 Colpidia. Hence the general impression, which corresponds to my 

 own observations, is oddly indecisive: enucleated stentors with 

 intact feeding organelles can ingest food but, like enucleated 

 amoebas (Brachet, 1955), usually do not. As a rule enucleates feed 

 little and soon become transparent as they void the food vacuoles 

 which were present in them originally; for, though incapable of 

 further digestion, they are quite capable of normal defecation 

 (Balbiani, 1889; Prowazek, 1904; and Schwartz, 1935). I have 

 found that the presence of but one macronuclear node was 

 sufficient to cause stentors to gorge themselves in the presence of 

 abundant food. 



II. Digestion in enucleates 



Using vital dyes as indicators, Balbiani (1893) found that food 

 vacuoles do not become acidic in enucleates as they do in normal 

 stentors, and in this he confirmed the work of Hofer in 1890 on 

 amoebas. Schwartz (1935) followed the fate of Colpidia which were 

 ingested by some of his enucleate coeruleus. Digestion was never 

 complete. From the start the food vacuoles were abnormally 

 swollen. Staining showed no dissolution of the ingested ciliates, 

 as occurred in controls. In one case I noticed that a motionless 

 rotifer in a food vacuole within an enucleated stentor remained 

 without apparent change for 4 days, although rotifers are normal 

 food of stentors. Hence it is very probable that the macronucleus 

 is necessary for digestion and hence for growth of the cell. 



Though apparently incapable of digestion, enucleated coeruleus 

 were able to utilize or cause the disappearance of their granular 

 carbohydrate reserves, though possibly at a slower rate than in 



