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Figure 1. Views of crows and apparatus for multiple choice experiments. A and 

 B, crows, number 3, d\ on shoulder of experimenter, and number 4, 9 , on 

 arm; C, the multiple choice box seen from the observer's room and from the 

 direction of approach by the crow, the compartments are numbered 1 to 9 

 and below each number is an entrance door. D, the same seen from the oppo- 

 site side or rear, with the nine exit doors closed. E, the box seen from the 

 observer's room, with entrance doors 1 to 6 and exit door 2 open. At the 

 extreme left, above the entrance door to the experiment compartment of the 

 fly, one of the crows is visible. F, the observer's table, showing curtain before 

 window (partially drawn aside to admit light for the camera) and the weighted 

 cords with pull buttons for opening and closing doors. 



