Washburn and Bentley, Color-Discrinunation. 121 



either dark or light red from blue, invariably biting hrst at the 

 red (Table I). 



How firmly rooted the association between the color red and the 

 biting impulse was by this tmie we learned when from August 16 

 to August 18, in a series of about seventy experiments, we under- 

 took to break it up and form a new association between food and 

 green. The same procedure in every respect was employed as 

 before, except that in the feeding experiments the food was always 

 placed in the green forceps. Dark red was still used on the other 

 pair, in these experiments, and light red in the unbaited tests, and 

 the forceps were again exchanged in such a way as to eliminate 

 error from smell. Because of the light which its behavior threw" 

 on the strength of the acquired impulse, we allowed the fish to 

 bite as many times as it would at the red (empty) forks and 

 recorded the number and order of the bites, in each experiment. 

 In the preceding series, the single experiment practically never 

 lasted beyond two or three bites, for if the fish bit first at the red 

 it usually got the food, and in the few cases where it bit first at the 

 green it bit but once and then either went down to the bottom of 

 the tank or swam over to the red. Not so in these final series. The 

 first time the subject entered compartment B, when the food was 

 in the green forceps, it bit fourteen times in succession at the 

 empty red sticks. It then bit once at the green, but not hard 

 enough to get the food, and, returning to the red, bit thirteen more 

 times at it. The fish then tried the green once more, came back 

 to the red for four bites, and then, when it went down to the bottom 

 of the tank, w^e considered the experiment over. At the second 

 test, the fish bit three times at the red, then went to the green and 

 got the bait at the third bite. In the next test, it bit ten times at 

 the red, then twice at the green, getting the food on the second bite. 

 At the fourth trial, the subject bit four times, but feebly, at the 

 red, came up once from the bottom between the two forceps, 

 "hesitated" and went down again, then came up, bit at the green 

 and got the food. In the fifth test, it came up toward the red, 

 seemed to look at it, sw^am to the green, nibbled, bit, and got the 

 bait. The sixth time, it bit first at the green but failed to seize the 

 food, turned to the red and bit once, then to the green and got the 

 mealworm in two bites. The seventh time, the chub bit only at 

 the green, taking four bites to obtain the food. The eighth time, 

 it bit first at the red, then at the green, securing the bait in two 



