252 The Animal Mind 



the forceps was measured by a stop-watch, and in the course 

 of 131 experiments the animal was not found to rise to the 

 green any less promptly than to the red. In other words, 

 no tendency to inhibit reaction to the green was shown, 

 although our later experiments proved that the fish 'could 

 distinguish the two (421). Apart from the difference in 

 .intellectual level between the fish and the monkey, it is 

 probable that the food- taking instinct was stronger in the 

 former, which came directly from the wild state, where it 

 could afford to lose no chances of nourishment. Dahl's 

 observation that the spider Attus arcuatus refused to take 

 house flies after having been presented with one smeared 

 with oil of turpentine, although it seized a gnat, is also a case 

 of inhibition involving discrimination of successively offered 

 stimuli (88). Cole, in his very interesting experiments on 

 the raccoon, raises the question whether discriminations of 

 this type do not involve memory images, and answers it in 

 the affirmative. He used the method to test discrimination 

 of colors, tones, forms, and sizes; the results have been 

 noted in earlier chapters. The cards used were placed on 

 levers so that by a touch they could be pushed up and 

 down. The animals learned to climb up for food 

 when one of two differently colored cards was shown, and 

 to stay down when the other one appeared; to distinguish 

 in a similar way between a high and a low tone, between 

 a round and a square card, and between a card 6| x 6J 

 inches and one 4^ x 4^ inches square. Of course the action 

 of climbing up was not itself purely instinctive, but had 

 become associated with the food instinct. The raccoons 

 also hit upon the trick of clawing up the cards themselves, 

 and if the one that appeared was the " no-food" card, they 

 would either claw it down again and pull up the other, or 

 proceed at once to pull up the other, leaving the "no-food" 



