VISION IN THE MOUSE 



573 



Method: A mouse was placed'upon the disk, raised to a cer- 

 tain height above the bench and allowed to jump down. The time 

 which elapsed from the instant the mouse was placed on the disk 

 till he jumped off was recorded with a stop-watch. The time was 

 taken as a measure of the animal's ability to perceive distance. 

 The mice were active and restless and continually peered down 

 over the edge of the board as though measuring the distance of 

 the leap. 



Nine animals were used in this experiment : 



With each mouse five trials were made daily, at each of several 

 different heights of the disk, and an average was taken of the time 

 records for these five. Usually if an animal was not off the disk 

 within two minutes it was recorded as unwilling to venture the 

 leap. 



Results: 



With plain bench-top below disk 



Large red and blue sheets of paper, when placed over the top 

 of the bench, gave similar results. 



When sawdust and scraps of paper were scattered on the bench, 

 the time was slightly lessened. This, however, may be due to the 



