w 



56 Animal Intelligence 



again and again in the course of this book to defend some 

 theory, dubious enough to my own mind, in the hope of 

 thereby inducing some one to oppose me and in opposing 

 me to make the experiments I have myself had no oppor- 

 tunity to make yet. Probably there will be enough op- 

 position if I confine myself to the theories I feel sure of. 



EXPERIMENTS WITH DOGS 



The boxes used were as follows : 



AA was similar to A (O at front), except that the loop was 

 of stiff cord f inch in diameter and was larger (3} inches 

 diameter) ; also it was hung a foot from the floor and 8 

 inches to the right of the door. The box itself was 41 X 20 



X2 3 . 



BB was similar to B, the loop being the same as in AA, 

 and being hung a foot from the floor. The box was of the 

 same size and shape as AA. 



BBi was like BB, but the loop was hung 18 inches from 

 the floor. 



CC was similar to C (button), but the button was 6 

 inches long, and the box was 36^ X 22 X 23. 



II was similar to I, but the box was 30 X 20 X 25 inches ; 

 the door (n inches wide, 6 high) was in the left front corner, 

 and the lever was 6 inches long and entered the box at a 

 point 2 inches to the right of the door and 4 inches above 

 the floor. 



In M the same box as in II was used, but instead of a 

 lever projecting inside the box, a lever running outside 

 parallel to the plane of the front of the box and 18 inches 

 long was used. This lay close against the bars compos- 

 ing the front of the box, and could be pawed down by 

 sticking the paw out an inch or so between two bars, at 



