46 ELIZABETH LOCKWOOD THOMPSON 



TABLE VIII— Continued 



No. of No. of No. of No. of 

 Snail days trials left right 



No. tested per day choices choices Eggs 



24 6 10 3 7 1 



25 10 2 8 1 



26 10 3 7 1 



15 7 10 8 2 



16 10 6 4 



17 10 9 1 1 



Total number of trials 240 



Total number of left turns 116 approximately 48% 



Total number of right turns 124 approximately 52% 



B. Experiments to test prejerence for an ascending or descending 

 ■path. If the cross bar of the U should not be horizontal, the 

 snail after ascending the stem would have a choice of a descending 

 path on one side and an ascending path on the other. In a 

 set of preference tests an attempt was made to determine whether 

 the animal showed preference for either of these paths. In 

 order to tilt the labyrinth at various angles the experimental 

 tank was placed on a small board, 8 1-2 in. by 10 in. by 1-4 in., 

 made of three layers to insure an unwarped surface. One end 

 of the board was pierced by two screw eyes set one inch from 

 the edge. By turning these screws the board, together with 

 the apparatus resting upon it, could be readily adjusted to any 

 angle. The angle used in each experiment was measured with 

 a Sterret spirit level. The slant of the right and left sides of 

 the path was frequently and irregularly reversed in order to 

 avoid any possible right and left habit formation during experi- 

 mentation. 



These tests were performed in the same way as those already 

 described and the records were similar. The tabulated results 

 follow. 



