Selection of Food in Stentor Ccerideiis {Ehr.) 



12 



Many paramecia in the act ot dividing were observed to have 

 from 5 to 15 vacuoles m them. Only one paramecium was found 

 to contain no ink or carmine in dividing. 



The paramecia of November 4 and 12 which had no carmine or 

 ink in them were of abnormal, boomerang shape. The number of 

 vacuoles in the paramecia in these vials was almost constant as 

 long as the experiment was carried on — over ^^ days. Attempts 

 were made at counting vacuoles and the average high number was 

 about 70. About 5 per cent ot the paramecia were found to con- 

 ta n only from 5 to 15 vacuoles. In a number of cases such indi- 

 viduals were isolated and fresh carmine or ink added, when they 

 would invariably fill up again. Ink was generally eaten more 

 readily than carmine. The paramecia acted normally as long as 

 the experiment was continued, and there was reason to believe that 

 the experiment could have been continued further if it had been 

 deemed necessary. 



As tor the S ten tors, throughout the entire run of the experiment, 

 none contained neither ink nor carmine. It was impossible to 

 count the vacuoles because of their irregular sizes and shapes. 

 The ink and carmine content of the Stentors was fairly constant. 

 No decrease in the amounts of these substances in the Stentors 

 was found throughout the entire experiment. 



It is clear from these experiments that if either Stentor or 

 Paramecium can be "educated" in such a way as to refuse to eat 

 carmine, etc., after feeding carmine to these organisms for a 

 month, it can only be done under very special conditions. Metal- 

 nikow does not describe his experiments in detail, but from what 



