ANIMAL INTELLIGENCE. 9 



animal loosened the bolt or bar which held it. Especial care 

 was taken not to have the widest openings between the bars at 

 all near the lever, or wire-loop, or what not, which governed 

 the bolt on the door. For the animal instinctively attacks the 

 large openings first, and if the mechanism which governs the 

 opening of the door is situated near one of them the animal's 

 task is rendered easier. You do not then get the association 

 process so free from the helping hand of instinct as you do if 

 you make the box without reference to the position of the mech- 

 anism to be set up within it. These various mechanisms are 

 so simple that a verbal description will suffice in most cases. 

 The facts which the reader should note are the nature of the 

 movement which the cat had to make, the nature of the object 

 at which the movement was directed, and the position of the object 

 in the box. In some special cases attention will also be called 

 to the force required. In general, however, that was very 

 slight (20 to 100 grams if applied directly). The various boxes 

 will be designated by capital letters. 



A. A string attached to the bolt which held the door ran 

 up over a pulley on the front edge of the box, and was tied to 

 a wire loop (2^ inches diameter) hanging 6 inches above the 

 floor in front center of box. Clawing or biting it, or rubbing 

 against it even, if in a certain way, opened the door. We may 

 call this box A '•O at front.'' 



B. A string attached to the bolt ran up over a pulley on 

 the front edge of the door, then across the box to another pul- 

 ley screwed into the inside of the back of the box 1 14^ inches 

 below the top, and passing over it ended in a wire loop (3 

 inches in diameter) 6 inches above the floor in back center of 

 box. Force applied to the loop or to the string as it ran across 

 the top of the box between two bars would open the door. We 

 may call V> ^O at back.'' 



Bi. In Bi the string ran outside the box, coming down 

 through a hole at the back, and was therefore inaccessible and 

 invisible from within. Only by pulling the loop could the door 

 be opened. Bi may be called '■O at back 2nd.' 



C. A door of the usual position and size (as in Fig. i) was 

 kept closed by a wooden button 3^/ inches long, 7^ inch wide. 



