A STUDY OF THE BEHAVIOR OF THE CROW 81 



These cords are indicated by dotted lines where they pass under 

 the floor of the multiple choice box or under the boards which 

 serve as an approach to the box : Elsewhere they appear as solid 

 lines. The arrangement of the cord-system within the experi- 

 ment room is rather unsatisfactorily shown in figure 1 F. 



On a table, J, before which the observer sits on the stool, 

 K, are two groups of cords, each with a wooden button attached 

 in a convenient position. The group at the experimenter's left 

 consists of the cords connected with the ten entrance doors, 

 and the group at the right, similarly, of those connected with 

 the ten exit doors. 



We may now trace the course of the cords from the doors of 

 compartment 9. A cord is fastened at a to the lower outer 

 corner of the entrance door t. It thence passes through the 

 screw eye b in the edge of the approach board. From this point 

 it extends, under the interrupted floor of the reaction chamber 

 H, to a screw eye, c, in a block across the aperture leading to 

 the experiment room. Thence the cord passes over a small 

 brass pulley at d and through a hole in the table J. (In figure 

 2 the pulley is hidden by the wooden button on cord.) It is 

 kept taut by a lead weight under J. Similarly, the cord for 

 the exit door of compartment 9 is attached to the lower outer 

 corner of the door at h, passes through the screw eyes, i and j, 

 to the pulley k, and is kept taut by a leaden weight. The cords 

 for the main entrance and exit doors, F and G, run to the extreme 

 left and right respectively of the experimenter's table. 



The experimenter operates a door by grasping the wooden 

 button shown on each cord in figure 1 F and pulling it toward 

 him. When he has pulled as far as the button will come, the 

 door to which the cord is attached stands wide open, and the 

 leaden weight under the table serves to hold it in this position 

 as long as the experimenter desires. When he wishes it closed, 

 he simply pushes the button back to its former position, and 

 the strength of the spring hinges suffices to overcome the pull 

 of the weight. 



In order that the bird should not see and be influenced by the 

 movements of the experimenter, a black curtain was hung before 

 the opening into the experiment room, and through small holes 

 cut in it, the experimenter was able to observe the movements 



