AN ANALYSIS OF THE LEARNING PROCESS IN THE SNAIL 43 



The second test was to find any possible preference for an 

 ascending or descending path. 



A. Experiments to test right or left preference. In the first 

 series an unpainted glass dish of beaker type, containing tap 

 water at room temperature was placed in the centre of the 

 experimental " house " and the ventilating spaces at the bottom 

 of the walls of the " house " were blocked to exclude light. 

 The air was forced from the lung of the snail by pressing its 

 body gently back into its shell. It was then placed against 

 the side of the dish at the four points of the compass in turn. 

 It was allowed in each case to crawl up the side of the dish for 

 air. The path was sketched and its right or left divergence from 

 a perpendicular noted. The snails were handled with forceps 

 and always placed on the horizontal bottom of the dish at right 

 angles to the surface to be traveled. The mucous trail left on 

 the sides of the dish was broken up after each trial by brushing 

 the traveled surface with a clean camel's hair brush. Three 

 snails, Nos. 15, 16 and 17, were used and four tests given each 

 on two consecutive da3'S. The record follows. 



TABLE VII 



Showing the deviation from a perpendicular shown by three individuals of Physa 

 gyrina Say, in following an unconfined path up the side of a cylindrical glass dish 

 in search of air. 



Trial Snail Snail Snail 



No. 15 16 17 



First day 1 Left Right Right 



2 Right Left Right 



3 Left Right Right 



4 Left Left Right 



Second dav 1 Left Left Right 



2 Left Left Left 



3 Right Right Right 



4 Right Left Right 

 Total 5L 3R 5L 3R IL TR 



Total number of trials 24 



Total number of deviations to the right 13 approximately 54 Sc 



Total number of deviations to the left 11 approximately 4o% 



This experiment was based upon the normal behavior of the 

 snail in its search for air; its path from the bottom of the dish 

 to the surface was not limited in any way. Besides the record 

 just given, three points of general interest were observed. 



