EXPERIMENTS IN EDUCABILITY OF 

 PARAMOECIUM 



Reactions to Touch. The purpose of the following ex- 

 periments was to determine what kind of modi f lability is 

 shown by Paramoecium due to recurring experiences of the 

 same kind. For this purpose first a capillary tube was se- 

 lected of a bore smaller than the length of the Paramoecium 

 and larger than his width. The animal was caught by the 

 upward suction of the tube and the tube was then placed on 

 a movable carriage, so the animal could always be kept in 

 the field of the microscope no matter what part of the tube 

 it might be swimming through. 



Once in the tube the Paramoecium swims to the forward 

 end and upon reaching the meniscus jerks backward for 

 several times its own length, then approaches again in a wider 

 spiral than before. This backing and approaching takes 

 place at least a dozen times and later the Paramoecium set- 

 tles down to a pecking movement, revolving anti-scriwwise 

 about the meniscus and attacking about five places in its 

 circumference. 



In the original approaching and retreating both move- 

 ments may be either screwwise or anti-screwwise. In ap- 

 proaching, both the screwwise and anti-screwwise movements 

 give about the same width of spiral, namely, a very slight 

 one. If the retreat is made anti-screwwise a relatively 

 straight course is followed, the spiral being hardly notice- 

 able. If the retreat is screwwise a very wide spiral re- 

 sults. 



In most cases the animal after a varying time bends its 

 anterior end around toward the aboral side, forming a "U" 

 with its body, and after a number of jerks succeeds in re- 

 versing the position of its body in the tube. In all cases it 

 turns toward the aboral side, thus using the long creeping 

 cilia near the buccal groove to obtain a hold on the side of 

 the tube. 



NINE] 



