5 

 ion resembles -fc he latch box with the exception £hat the 



latch was inside the box and was released in a different 

 manner. A wire chain connected with the latch passed 

 over two pulleys attached to opposite corners of the up- 

 per frame work inside the box, then through the mesh of 

 the wire netting to an inclined plane behind the box. 

 Thus a rat stepping on the plane would release the latch 

 fro;; the notch and the door would open inward. The plane 

 was about seven inches long and three inches wide and 

 was hinged to the top of the table on which the box rested, 

 It was about ' 3 -hind the box and made an angle of 

 about 15' with the table top when the door was closed, 

 like the latch box, the inclined plane box was covered 

 with a wire hood. 



METHODS OF EXPERIMENTATION. 

 Young white rats were used for experimentation. 

 Usually, when thirty-five days old the mother and her lit- 

 ter were separated. 7/hen forty to forty-five days old 



