BEHAVIOR OF WHITE RATS IN PRESENCE OF CATS 21 



cated the performances previously reported. The exploratory 

 movements were totally inhibited. The otherwise tense posi- 

 tion of the rats was varied by a slight trembling and a sort of 

 spasmodic contraction in the region of the viscera. The whole 

 attitude of the rats seemed to indicate fear. At the end of five 

 minutes, the cat was removed. During this time the rats had 

 not changed their tense position, the head being held up and 

 out, the feet planted squarely on the floor, the body slightly 

 crouching, the respiration accelerated for a few moments and 

 then momentarily retarded. 



In another series, the rats were left undisturbed in their nests, 

 the cats being brought into the room and placed upon the cages 

 or within them as the circumstances warranted. The behavior 

 of the groups was still more striking than had been the case with 

 the single rats or with the pairs. In the first trial, a cat was 

 placed on the cage containing the five-months-old rats. Within 

 a few seconds, activity had completely ceased in the cage and 

 within thirty seconds all the rats, save one (described below), 

 had retreated to one corner of the cage and were there massed 

 together. Some of the rats were displaying the same convulsive 

 movements of the viscera, and occasionally a low whine was 

 detected. When the cat was placed upon the cage containing 

 the two-months-old group, the responses were more intense than 

 in the previous case. There was considerable nervous jumping. 

 The huddling together would last for a few seconds, and then, as 

 some noise or some movement of the cat occurred, the rats would 

 run distractedly here and there and finally collect again in a 

 corner. A mother and two young about four weeks old confirmed 

 previous observations. The young seemed very much dis- 

 turbed and did not recover for more than two hours. The 

 mother retreated to one corner of the cage and remained there 

 for over an hour. Another female was suckling a litter of five 

 young, about two weeks old, when a cat was placed upon her 

 cage. She hastily left the nest and backed to the rear of the cage 

 with the same characteristic performance. A mother caring for 

 a litter of nine, which were one day old, likewise hastily left the 

 nest dragging three of four young with her. She crouched at 



