22 



E. J. LUND 



TABLE 5 



Experiment II 

 Set 1. Stimulated 



NUMBER OF GRAINS EATEN BY EACH INDIVIDUAL 



1 



2' 



1 2 



3 1 



2 



2; 6 



1| 3| 

 Oj 0, 



3I 





 1 1 

 3: 3 



AVG. PER 

 IND. 



grains 



1.1 



0.56 



1.60 



Total average. 



1.08 



Total average. 



control. If a smaller pipette is used or a larger one, and the stimu- 

 lation, by sucking them along \vith the medium up into the pipette, 

 is more violent, it will stimulate and injure the organisms so that they 

 will not eat at all, or at least, not for some time after stimulation. Of 

 course structural injuries are very easily produced, with the result that 

 regulation of the cell must take place before any food can be eaten 

 (table 5). 



Proof that in this experiment, Set 1, if not in Set 1 of Experi- 

 ment III, the organisms were not injured beyond the capacity 

 for swallowing, is found in the fact that the great majority did 

 eat, though only a comparatively small number of grains An- 

 other experiment may be given to illustrate the same fact. 



Experiment III. The animals in Set 1 were not stimulated before 

 feeding, but after they had fed for five minutes they were stimulated 

 by drawing the suspension with the animals in it, up into the pipette 

 only once. Material from a different culture was used in this experi- 

 ment; time of feeding fifteen minutes. The control suspension with 

 the organisms was redistributed once by gently shaking the dish. The 

 animals were all normal in form at the end of the experiment (table 6). 



In Experiment III the stimulus was only slight as compared 

 to that in Experiment II, yet the effect was marked As stated 

 above, strong stimulation may totally prevent feeding. 



