Animal Intelligence 



a point about 15 inches high and 6 inches in from the 

 right edge of the front. We may call M 'Lever outside. 1 



, -7 * ' ' 



6-aZ. 3 



FIG. 13. 



N was a pen 5X3 feet made of wire netting 46 inches 

 high. The door, 31 X 20, was in the right half of the front. 

 A string from the bolt passed up over a pulley and back to 

 the back center, where it was fastened 33 inches above the 

 floor. Biting or pawing this string opened the door. 



