VISION IN THE MOUSE 



551 



Method : Food was placed in one of the boxes and the electric 

 current was switched into the wires on the board which supported 



Fig. 1 Apparatus to test visual discrimination in the mouse. N, nest box; 

 X and Y, food boxes; I.C. inductorium; C, dry cell; K, key. 



the other box. In this way inducement was given to cause the 

 animal to make use of what discriminative power it might possess 

 for the purpose of avoiding the shock and obtaining the food. 

 This, of course, presupposes the possibility of the formation of an 

 association of shock with one intensity of light and of food with 

 the other. The food used in this experiment was a small quantity 

 of "force," which has little or no odor to enter as a disturbing 

 factor. 



An animal was placed in box N and the door was lifted. The 



