20 COLEMAN R. GRIFFITH 



hand with cat-odor by rubbing a cat" (p. 98). He did find, 

 however, that adult rats with no experience showed some uneasi- 

 ness, which, with other facts, led him to think that "the mani- 

 festation of instinctive fear waits upon the integration and 

 functioning of the higher centres' ' (p. 99). 



The problem is not solved. It calls for experimental isolation, 

 further description of the performances previously noted, and a 

 determination of the specific relation between the responses 

 and the presence of the cat. Several questions should then be 

 answerable: to wit, (1) What is the chief sensory channel through 

 which the responses are induced, i.e., what is the specific factor 

 in a cat that should excite such behavior? (2) What relation 

 obtains between the response and the age and sex of the rats? 

 (3) What is the relation of this type of behavior to other well- 

 known types of behavior? 



For further work, five groups of docile white rats, varying in 

 age and sex, and three females with litters, were used as subjects. 

 Five cats, two dogs, a variety of odorous chemicals, and some 

 mice and common Norway rats, were used to excite the responses. 

 In a part of the experiments, the rats were undisturbed in their 

 nests on an iron frame, the exciting object or substance being 

 placed upon or in their cages after it had been brought into 

 the room. In this way, a minimal disturbance in the normal 

 living conditions was hoped for. In another part of the experi- 

 ments, the rats were taken, singly or in pairs, to the object 

 provided in another room. For this purpose a wire puzzle-box 

 was used to hold the rat. Over the puzzle box was set a large 

 glass observation-frame inside of which the cat or other object 

 could be placed. 



In the first group of experiments, an effort was made to isolate 

 the responses and to give a complete description of them. Two 

 female rats about five months old were placed in the puzzle-box. 

 As is usual with normal rats, they began vigorously to explore 

 the new environment. In all experiments of this kind care was 

 taken to note the immediacy and the energy of this initial explora- 

 tion. Within a second or two after the introduction of a cat 

 under the large observation frame, the subjects suddenly dupli- 



