Selection of Food in Stejitor Cccrideus (Ehr.) 127 



surface texture was quite destroyed. This "jelly" was then 

 sucked up and fed to Stentors together with normal living organ- 

 isms of the same species. The whole specimens were eaten but 

 the "jelly" was rejected. The Stentors bent away or reversed 

 their cilia the moment the mashed paramecia or Euglenae touched 

 the disk or pouch, exactly as they do when a cloud of carmine 

 ink, etc., is similarly caused to come in contact with the Stentor. 



Small starch grains were then mixed with this jelly and diluted 

 and fed to the Stentors. No starch grains were eaten. The 

 Stentors still reversed their cilia when any of this mixture touched 

 the disk. 



Starch grains (potato and corn) were then fed in solutions of 

 various strengths of sugar, beef juice, pork juice, pepsm, Liebig's 

 Extract of Beef. The starch was invariable rejected. This 

 same thing was tried with carmine and india mk, but the same 

 results were got here as were derived from the controls; no more 

 carmine or ink was ingested if pork or beef juice, or sugar, was 

 present, than when these were absent. 



Still other experiments were carried on in which the food 

 organisms were soaked in various chemicals such as iodine, anilin 

 dyes, alcoholic solutions of quinine, etc., and then only part of the 

 superfluous chemical was washed away, so that when fed, a little 

 of the iodine, quinine, etc., would be in solution and th.us give the 

 Euglen^ or paramecia quite a different "taste" from that which 

 these organisms normally possess. These experiments are very 

 difficult to carry out, owing to the fact that when iodine or quinine 

 is just a little too strong, the Stentors contract the moment these 

 substances touch the disk, and yet if one washes these chemically 

 treated organisms a little longer one cannot be sure that any iodine 

 or quinine remains to affect the Stentor before the organisms are 

 swallowed. The experiments are also somewhat uncertain, for 

 in the case where an organism is eaten, we cannot be sure whether 

 the quinine, dve, or iodine, etc., had any effect on the Stentor at 

 all. But the following are the results. When the food organisms 

 were not too vigorously washed, the Stentors that were fed with 

 them bent away or contracted the moment the stream from the 

 pipette touched the disk. When the washing was carried a little 

 further the organisms were ingested as were the living organisms. 



