124 J. C. DeVOSS AND ROSE GANSON 



drawer and thus any odor peculiar to a certain pigment must 

 have been pretty well diffused through them all. 



There seems to be an almost irrefutable proof that our pre- 

 cautions were successful in at least a large number of cases. 

 This proof rests in the fact that we obtained many complete 

 confusions and, as already stated, each confusion was controlled 

 by second cat or follower, which made it certain that the con- 

 fusion was not due to accidental circumstances nor to some 

 individual peculiarity of the first cat. 



In working through the series of Bradley colors we came 

 gradually to those among which confusion was difficult (required 

 at least two hundred forty trials to attain twenty-four correct 

 choices in a series of thirty trials). Then we came to colors 

 which were confused with the food-color. We shall call these 

 groups of colors, respectively, areas of "difficult-discrimination" 

 and "confusion-areas," though in some cases these "areas" 

 overlapped, i. e., one color was confused with the stimulus color, 

 the next was discriminated from it with difficulty, the next was 

 confused with it etc. 



Tables I, II, and III show typical cases of discrimination, 

 difficult discrimination, and confusion. 



TABLE I (A) 



Typical Discrimination by Series 



Cat 2 



Stimulus Color — Yellow 



