VISION IN THE MOUSE 



571 



to make the illumination of the apertures more homogeneous, as 

 well as to reduce the light. 



The electric shock (as punishment for a wrong choice) was given 

 in the compartment with the X-aperture, the side exit on that side 

 being closed with a piece of glass. When the animal entered the 

 compartment marked By the circle, it was allowed to pass into 

 the alley and to obtain food. 



The circle and X were interchanged at intervals, usually after 

 three or four choices had been made. This was accomplished by 

 sliding the carriage a few inches to the right or left so that another 

 card with an X-aperture would come into the field, taking the 

 circle's place, the circle having moved into the position of the 

 former X. Ten choices were obtained each day. Four mice were 

 used in this experiment. 



Results: In the following table, R stands for right choices, 

 i.e., circle; W for wrong, i.e., X-aperture. 



1st 



2nd ... 

 3rd... 

 4th. . 

 5th.... 

 6th... . 

 7th.... 

 8th. ... 

 9th 



10th... 

 11th... 

 12th . 

 13th... 



Totals 



Xd 



26 



24 



39 



2] 



