328 Journal of Comparative Neurology and Psychology. 



means of smell, or by kinesthetic impressions. It will be re- 

 membered that when the simple wire box was placed before 

 the guinea pig, it r.in in exact!}' as it was accustomed to do, 

 although no food was inside. The box itself was then the 

 stimulus, as being associated with food 



To determine how quickK^ the odor of food alone could 

 set up the association, a scries of experiments was designed, 

 in which the visual factor was eHminated. 



Text-figiin- S. 



The apparatus used in this test was a simple wooden box, 

 6^2 by 6^ by 6^2 inches, with numerous small holes bored in it 

 (Text-fig. 8). A door was swung by hinges at the top A cop- 

 per spring inside the door made contact with a plate in the top of 

 the box when the door was pushed open. Connection was made 

 with an electric light in a dark box entirely outside the experi- 

 mental cage. The experimental cage was covered with a black 

 cloth frame, and all experiments were performed at night, so 

 that no light should be present. Noises and other accidental 

 disturbances were thus diminished. 



In the first series of experiments it was possible, after the 

 reaction had been made and the light turned on, for a faint 

 glow to penetrate the cloth covering of the experimental cage. 

 At a later time these results were verified in the dark room 

 where no light could enter, and the arc connected with the ap- 

 paratus was so arranged that no illumination of the room was 

 possible. 



The typical series gix'en was taken from an adult guinea 

 pig about nine months old, of the smooth English variety. It 

 had not been used before for any experimental work, and there- 

 fore the first thing that had to be done was to tame it, and ac- 



[36] 



