SELECTION OF FOOD IN STENTOR CERULEUS 



(EHR.)' 



ASA ARTHUR SCHAEFFER 

 With Two Figures 



Introductory y c 



Material yg 



Food of Stentors. 



79 



Methods of investigation go 



Normal behavior of Stentor gi 



Behavior in rejecting particles gj. 



Experiments with specific particles ' gg 



Experiment i Discrimination between Phacus and sulphur gg 



Experiment 2 Discrimination between starch grains and Phacus go 



Experiment t, Discrimination between starch, glass, and Phacus 02 



Experiment 4 Selection of Phacus and Euglena from sulphur and glass oi 



Experiment 5 Discrimination between Phacus triquetur and P. longicaudus 06 



Experiment 6 Discrimination between different species of organisms 06 



Experiment 7 Discrimination between different species of organisms 06 



Experiment 8 Discrimination between organisms of similar size and shape loi 



Experiment 9 Effect of hunger on behavior in feeding 104 



Experiment 10 Effect of satiety on behavior in feeding 104 



Experiment 1 1 The effect of utter satiety on Stentor 



Experiments wi th mixtures of particles 



The basis of selection 121 



The selective mechanism 12c 



Summary 126 



References 128 



INTRODUCTORY 



The question whether protozoa can exercise selection in the kind 

 of material which they feed upon has called forth expression of 

 opinions from almost every worker upon the protozoa. The inges- 



' From the Laboratory of Experimental Zoology, Johns Hopkins University. The author of this 

 paper is indebted to Prof. H. S. Jennings under whose direction this investigation was carried on. 

 The Journal of Experimental Zoology, vol. viii, no. i. 



