676 Journal of Comparative Neurology and Psychology. 



In order to exclude this type of discrimination, we first placed 

 the colored papers inside the glasses. We believed that this would 

 so diminish the pigment odor, if it did exist, as to put it below the 

 threshold of the animal. Or, if not, that it would so reduce the 

 pigment odor that it would be completely eclipsed by the food odor 

 when food was placed in all the glasses. In the light of the experi- 

 ment above, in which apple was used as a stimulus, it is practically 

 certain that, with the colored papers inside the glasses, no odor of the 

 pigment could be sensed by the raccoons. 



The effect, for the human eye, of putting the paper inside the 

 glasses was to make only a vertical strip of color visible in each 

 glass. While the intensity of the colors seemed much reduced, the 

 reduction seemed equal for all the papers, so that differences in 

 brightness seemed no more pronounced than before. The test proved 

 to be a very difficult one. We had taught the animals to select 

 VBT 2 as a food-color when the papers were on the outside of the 

 glasses. We continued to use it as a food-color after putting them 

 within the tumblers. The results of the experiment are shown in 

 Tables 20 and 21. 



TABLE 20. 



VBT 2 in Group 5. — Papers inside the Glasses. 



Raccoon No. 2. 



* Our supply of OYS 1 was exhausted and on this day we used a second 

 glass covered with Gray 5 to which the responses were 5, 5 and 4, respectively. 



Though only the vertical strip of color was visible, the raccoons 

 succeeded in selecting the food-glass twenty-five and twenty-six times, 

 respectively, on the fourth day of training. 



