32 Animal Intelligence 



D. The door was in the extreme right of the front. 

 A string fastened to the bolt which held it ran up 

 over a pulley on the top edge and back to the top edge 

 of the back side of the box (3 inches in from the right 

 side) and was there firmly fastened. The top of the box 

 was of wire screening and arched over the string J inch 

 above it along its entire length. A slight pull on the 

 string anywhere opened the door. This box was 20 x 16, 

 but a space 7X16 was partitioned off at the left by a wire 

 screen. D may be called 'String.' 



Di was the same box as B, but had the string fastened 

 firmly at the back instead of running over a pulley and 

 ending in a wire loop. We may call it 'String 2d.' 



E. A string ran from the bolt holding the door up over a 

 pulley and down to the floor outside the box, where it was 

 fastened 2 inches in front of the box and ij inches to the 

 left of the door (looking from the inside). By poking a paw 

 out between the bars and pulling this string inward the door 

 would be opened. We may call E 'String outside. 1 



In F the string was not fastened to the floor but ended in a 

 loop 2 J inches in diameter which could be clawed down so as 

 to open the door. Unless the pull was in just the right direc- 

 tion, the string was likely to catch on the pulley. This loop 

 hung 3 inches above the floor, and i j inches in front of the 

 box. We may call F 'String outside unfastened.' 



G was a box 29 x 20 J x 22}, with a door 29 x 12 hinged 

 on the left side of the box (looking from within), and kept 

 closed by an ordinary thumb latch placed 15 inches from 

 the floor. The remainder of the front of the box was closed 

 in by wooden bars. The door was a wooden frame covered 

 with screening. 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 



