ROLE OF NUCLEUS IN CELL FUNCTIONS. 389 



According to Hofer, Lynch and others, enucleated fragments of 

 amoebae do not ingest food. Stole declares that amoebae ingest 

 food in a perfectly normal manner for many days after enuclea- 

 tion. Schaffer (1920) has pointed out that feeding calls for con- 

 certed streaming, and whether enucleated amoebae ingest food or 

 not is certainly of great importance in evaluating the importance 

 of the nucleus in cell regulation of amoebae. 



Figure 17 shows an A. dubia in the normal act of feeding with 

 the interesting observation of one smaller food cup superimposed 

 upon one arm of a large food cup. In culture fluids swarming 

 with Chilomonas and Euglenx, the writer has never observed an 

 enucleated amoeba ingest a food substance by means of a food 

 cup. It has been observed that such a fragment may flow over 

 a Chilomonas, when it appears as if a small cup were formed in 

 the under side of the pseudopod, but on no occasion was the 

 act of enclosing the flagellate and engulfing it into the proto- 

 plasm completed. 



Schaeffer (1922) has mentioned that by stimulating an amoeba 

 with a fine glass rod by waving it in the water some distance from 

 the amoeba, the amoeba may form a food cup (Fig. 27). While 

 this reaction is not difficult to produce in the case of an entire, 

 healthy amoeba, in the case of an enucleated amoeba there is 

 either no reaction to a vibrating needle, or only an abortive 

 pseudopod is extended (Fig. 28). 



Although enucleated amoebae which had ingested very large 

 Euglenae could often be found, one was never observed in the act 

 of feeding. Once the writer put a large enucleated fragment of 

 an amoeba in a drop of water containing many Euglenae and sat 

 down at the microscope to watch it until the process of feeding 

 should be observed. It was noted that Euglenx which had no 

 flagella often approached the amoeba by the typical "euglenoid 

 movement," but the amoeba did not react positively toward it. 

 After about an hour it was observed that an Euglena was batter- 

 ing the amoeba in its attempts to go forward (Fig. 18). Instead 

 of showing an "avoiding reaction," it would simply recoil, and 

 make a new attempt to go forward in the same direction. Soon 

 it had literally battered an entrance into the amoeba (Figs. 18, 

 19, 20, 21 ). Finally the channel was deep enough to enclose 



