q6 Asa Arthur Schaeffer 



The first experiment was designed to show whether selection was 

 exhibited when Phacus triqueter and Phacus longicaudus were fed 

 in mixed order, Phacus triqueter being much more numerous than 

 Phacus longicaudus. 



Experiment J. Dtscri^nination between Phacus triqueter and 



P. longicaudus 



(See Table V) 



Out of the five Phacus longicaudus which were fed with the 

 176 Phacus triqueter, four were rejected and one was ingested. 

 The four rejected ones were the last members of the respective 

 groups in which they were fed, and the one which was ingested 

 cane first in the group of two — 166I, 167. It was not positively 

 ascertained in any of my experiments whether discrimination is 

 nicer among the last members of a group than among the first, 

 but the evidence seems to point that way. But even if this should 

 turn out not to be true, it seems clear that actual discrimination 

 between Phacus triqueter and P. longicaudus took place in this 

 experiment. 



Experiment 6. Discrimination betiueen Di fferent Species of 



Organisms 



In another experiment designed to further show selection oi one 

 or more kinds of food particles from as many as six different spe- 

 cies of organisms, the following results were obtained. There 

 were fed in mixed order, Euglena viridis, Euglena deses, Phacus 

 triqueter, Phacus longicaudus, Trachelomonas hispida, and Trache- 

 lomonas volvocina. All these organisms were fed from a 

 single pipette on to the disk of a Stentor as in the preceding ex- 

 periment. For results see Table VI, p. 99. 



Experiment y. Discrimitiation hetiveen Different Species of 



Organisms 



Immediately following the above experiment I fed another 

 Stentor with the same sorts of flagellates (but omitting the Eug- 

 lena deses which is difficult to handle in a capillary pipette owing 

 to its habit of sticking to the walls) with the results shown in 

 Table VI, p. 100. Loops are not recorded. 



