Selection of Food in Stentor Cceruleus {Ehr. 



99 



ev = Euglena viridis; ed = Euglena deses; pt = Phacus triquetur; pi = Phacus longicaudus; th = 

 Trachelomonas hispida; tv = Trachelomonas volvocina. 



TABLE VI 

 Experiment 6. Discrimination between Diferent Species of Organisms 



*Food particle 64 was a Coleps hirtus. 



ingested does not prove that there was no selection going on in 

 this part of the experiment, for the Phacus triqueter and the Tra- 

 chelomonas hispida are without exception rejected. The explan- 

 ation of this apparently capricious selection of some ?2uglenae and 

 the rejection of the rest is probably to be sought in the changed 



