HABIT FORMATION IN FROGS 333 



caterpillar. In the case of the stentor and of the hermit crab, 

 the presence of the objects themselves were the cause of the 

 examination; the previous experience with these objects did 

 not change the examining process. Examination of the char- 

 acter described for Rana clamata (medium) is therefore not 

 instinctive; it must be a psychic process. 



This is as far as the writer wishes to go at present. It is all 

 we can safely conclude from the behavior of the frogs as de- 

 scribed in the early part of this paper. 



We ha\'e seen that the rapid learning cannot be due to a 

 shock received from a very disagreeable or painful stimulus; 

 that the rejection of the hairy caterpillars is not instinctive; 

 and that the extended examination of the hairy caterpillar is 

 probably not a physiologic or instinctive process, but very 

 probably a psychic one. I think that we can safely sav that 

 these points are established, at least in our working program. 

 It now^ remains for us to give the ps}xhic processes, which we 

 have established by a process of elimination, descriptive names. 



That part of the behavior of Rana clamata (medium) in- 

 volved in examining the hairy caterpillar seems a clear case of 

 defining of the construct of hairy caterpillar. Certain qual- 

 ities, possibly movement was one of them, supplied the stimulus 

 which under other circumstances w'ould have set off the feeding 

 instinct. In this case a peculiar crawling movement served 

 as a stimulus (though perhaps not the only one) to construct 

 a hairy caterpillar through association. Experience with hairy 

 caterpillars taught the frog that such objects were to be avoided 

 as food. When the construct of hairy caterpillar was defined 

 to such a degree that association between it and disagreeable 

 hairy caterpillar was perfect, examination ceased and the cater- 

 pillar was left. But after the catei-pillar had crawled up the 

 side of the cage and had fallen into the water, the frog's atten- 

 tion was again called to the " wrigglings " of the caterpillar, 

 a quality of movement which the frog had not observed before 

 in the caterpillar; hence, the construct of hairy caterpillar had 

 to be revised by further definition. After the construct had 

 passed from the vague to a final definite stage, can w^e say that 

 there existed in the frog's memory a representation of the pre- 

 vious experience with hairy caterpillars? There is sufficient 

 evidence here to justify us in seriously asking the question, 



t' 



