ANIMAL INTELLIGENCE. II 



It was not arranged so as to open as soon as the latch was 

 lifted, but required a force of 400 grams, even when applied to 

 the best advantage. The bar of the thumb-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 'T/iuinb-Iatch.' 



H was, except for the opening where the door was situated, 

 a perfectly solid and dark box. In the front was cut an open- 

 ing about 9x7 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 swinging 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 2yi inches in from the right side of the box. In its normal 

 position its inner end was 5 ^ inches above the floor. A de- 

 pression 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 contrary, 

 the door was held closed by a small piece of board (4 x 3^ x ^ 

 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.' 



K was a box arranged so that three separate acts were re- 

 quired to open the door, which was held by two bolts at the top 

 and two bars outside. One of the bolts was connected with a 

 platform in the back center of the box so that depressing the 

 platform raised the bolt. The other was raised by a string 



