Experimental Study of Associative Processes 33 
latch, moreover, would fall back into place again unless the 
door were pushed out at least a little. The top of this box 
was not of bars or screening, but solid. We may call G 
‘Thumb latch.’ 
H was, except for the opening where the door was situated, 
a perfectly solid and dark box. In the front was cut an 
opening about 9 X 7 inches. A wooden frame covered with 
wire netting hung in front of this. It was fastened to the 
box only by a screw through the middle of the frame’s top 
piece, and could therefore be pushed to either side so as to 
permit escape from the box if it were prevented from swing- 
ing back into place. 
I was a box 12 X 14 X 23. The door was 8 inches wide, 4 
high, and hinged at the left side. It was held closed by a 
wooden bar which moved easily on a pivot and which could 
be pushed up by another bar which projected 5 inches into 
the box. This second bar was pivoted so that downward 
pressure on it pushed the first bar up and let the door swing 
open. The second bar entered the box at a point 4 inches 
above the floor and 23 inches in from the right side of the 
box. In its normal position its inner end was 5% inches 
above the floor. A depression of 2 inches at that end was 
necessary to open the door. Of course, nearer the pivot a 
shorter depression would do. The front of the box was 
closed by bars, but the rest by solid boards. We may call I 
‘ Lever.’ 
J was the same as B except that the door was not opened 
by a weight as soon as the bolt was pulled up. On the con- 
trary, the door was held closed by a small piece of board 
(4 x 3% x 34 thick) placed against it outside. After 
pulling the loop at the back the cat had to knock down 
this support and push the door open. We may call J 
‘Double.’ 
D 
