104 ^sa Arthur Schaejfer 



Experiment g. Effect of Hunger on Behavior in Feeding 



Eight Stentors with some of their own culture solution were 

 placed into a small preparation dish. After they had attached 

 themselves I selected a large individual and fed it with Phacus 

 triqueter with the result shown in Table IX. 



Experiment lo. Effect of Satiety on Behavior in Feeding 



At the close of the foregoing experiment the dish of Stentors 

 was set aside until next day when it was found that the Stentor 

 which was fed in this experiment contained a considerable num- 

 ber of small brownish bodies. These upon close examination 

 were found to be Phacus triqueter in a stage of partial digestion. 

 The protoplasm was extracted from the Phacus and the chloro- 

 phyll was changed m color. Here was then a good opportunity 

 to see whether the ingestion of Phacus on the previous day had 

 any effect upon the ingestion of food particles today. A mix- 

 ture of Euglena viridis and Phacus triqueter was fed from a cap- 

 illary pipette on to the disk of Stentor with the results shown in 

 Table X. 



Perhaps the most notable difference between these two experi- 

 ments is in the number of food particles ingested. In the ninth 

 experiment 'j'^ out of Ii8 particles were eaten, the majority being 

 ingested in the first half of the experiment, while in the tenth only 

 10 were eaten out of 75, and these ten were distributed compara- 

 tively evenly. A large number of experiments performed upon 

 well-fed Stentors showed substantially the same results as Ex- 

 periment 10. In no case where the membranellre and pouch cilia 

 beat normally, i e., where their movement was not reversed, did 

 it happen that every single particle was rejected. Some few were 

 always ingested if the experiment was sufficiently extensive. The 

 lowest ratio of particles eaten to those fed was i to 12. When 

 the particles were fed very rapidly the ratio was very much in- 

 creased. But if the particles are fed at the rate of about 100 an 

 hour, results like those of Experiment 10 will be obtained. Sten- 

 tors from artificial cultures in which food is very plentiful, and in 

 which the Stentors thrive and reproduce very rapidly, show sub- 

 stantially the same results as are shown in Experiment 10. 



