532 THE AMERICAN NATURALIST [Vol. LIV 



hungry, frequently refused to eat immediately after 

 earlier turnings, although later they eat quite readily. 

 Other evidence of a general organic disturbance is found 

 in the violent trembling which frequently seized some of 

 the rats during a given series. This trembling was dis- 

 tinct from that behavior mentioned before which reminds 

 one of nothing so much as the retching of nausea in 

 human beings. I have failed to find a single case of nau- 

 seation in the rat which resulted in an esophageal dis- 

 charge. The retching did not seem to occur so readily if 

 the rat had had food before the rotational period. The 

 trembling was by far the most characteristic performance 

 and was common to most of the subjects. That the trem- 

 bling was organically based could be determined by hold- 

 ing the rat just after turning. The visceral organs 

 seemed to be convulsed. The eyes were partially closed 

 and the vibrissas trembled violently because of the trem- 

 bling of the mouth parts. This behavior occurred for 

 two or three days after the series had been started and in 

 the case of some of the subjects was the last observable 

 response to the rotation. 



4. It is difficult to get a quantitative test for these or 

 for more specifically kinesthetic responses. The only test 

 used in this connection was an enumeration of the num- 

 ber of spontaneous movements made before, during, and 

 after rotation, as the series progressed. Prior to all rota- 

 tion, the exploratory movements are prominent. As rota- 

 tion takes place for the first time two kinds of response 

 are in evidence. First, the rat may make frantic efforts 

 to move in the direction contrary to rotation so long as 

 the platform moves. When the movement ceases the rat 

 turns and attempts just as vigorously to move in the oppo- 

 site direction. These attempts always cease in five or 

 six seconds : they seem to reach their term with the after- 

 nystagmus. The other characteristic response is illus- 

 trated by those subjects which squat tensely on the floor 

 of the rotating platform with the head turned far in the 

 direction against rotation. There seems to be a specific 



