580 



KARL T. WAUGH 



Mice with black eyes. Partitions same distance from X; changed at irregulai 

 intervals, usually after two or three trials. 



In the next experiment the mice T, X, BF, and U were allowed 

 to run back and forth through the box all night. The following 

 morning while they were in the enclosure A, the partitions were 

 interchanged and they were allowed to run through the box one 

 at a time. They were then taken back and the process was re- 

 peated. In the eight trials, seven were wrong and one right. The 

 same thing tried on a subsequent morning resulted in eight wrong 

 choices. 



Partitions nearer to the animal, but at the same distance from each other {5 cm. i 

 One at 5 cm. the other at 10 cm. from X 



NO. TRIALS 



DOUBTFUL 



Xc. 

 Xa. 

 Xd. 

 Xe. 



One partition 5 cm. from the passageway, the other 15 cm., making <> depth of 10 cm. 

 fO be perceived 



In all of the white mice there was observed a peculiar head 

 movement from side to side while crouching in the passageway, 

 preparatory to running forward. Since the results in the matter 

 of depth-perception favor the white mice — for the black-eyed 



