AN ANALYSIS OF THE LEARNING PROCESS IN THE SNAIL 45 



allowed to feed undisturbed while the other two snails of the 

 group were tested in a similar way. After each test the celluloid 

 apparatus was removed to a separate dish of water and thoroughly 

 cleaned with a stiff brush in order to remove the mucous trail 

 left by the tested snail and thus make it impossible for the next 

 snail to follow the trail. 



A complete record was made for each test given to each 

 individual snail. Yerkes' method (1912), modified to suit the 

 experiments, was adopted in making the records. Outlines of 

 the labyrinth were drawn on separate slips of paper and the 

 course chosen by each snail traced on one of these. The time 

 required for the trip was taken with a stop-watch. The additional 

 data of date, time of day, and temperature were added to the 

 slip, and a record was also made of the eggs, if any, which had 

 been deposited within twenty-four hours previous to the tests. 

 It was thought that a later analysis of the records might show 

 some relation between the physiological condition of the animal 

 caused by ovulation, and the results of the experiments. 



The following table shows the results obtained from a series 

 of forty tests on each of six snails. . 



TABLE VIII 



Showing the right and left preference of six individuals of Physa gyrina Say, 

 which had been deprived of air and placed at the base of a vertical U-shaped path 

 resting on an upright stem. Both arms of the U reached the surface. The 

 horizontal of the U necessitated a choice of paths (fig. 14, Plate IV) 



