188 STUDIES IN GENERAL PHYSIOLOGY 



its eyes are rotated more or less about the long axis of the 

 body toward the left, so that the left eye looks downward, 

 while the right eye looks upward. The (persistent) geo- 

 tropic movements of the eyeballs upon changing the orienta- 

 tion of the animal toward the center of the earth still occur, 

 with this modification, however, that when the whole animal 

 is turned about its longitudinal axis the amount of the com- 

 pensatory movement of the eyes is added algebraically to 

 that caused by the lesion of the ear. 



4. Only a slight change is noticeable, usually, in the posi- 

 tion in which the pectoral fins are kept. The left lateral 

 fin is turned toward the back while the right is turned 

 toward the abdomen. 



II. If the otoliths of such an animal are removed from 

 the other side also, all the phenomena described above dis- 

 appear. Instead, however, now the following abnormalities 

 appear : 



1. The animal is no longer compelled to turn its ventral 

 side toward the center of the earth. If one carefully attempts 

 to lay it upon its back the animal does not resist, and when 

 prevented from falling over, it remains permanently upon its 

 back. When left to itself, the animal is often found lying 

 upon its back, or swimming in this position, even when it is 

 entirely well and vigorous. 



2. The permanent alterations in the position of the eye- 

 balls, when the orientation of the animal toward the center 

 of the earth is changed, are lacking. 



III. If the antrum is opened and the same injuries are 

 inflicted as are necessary to remove the otoliths without, 

 however, injuring these or the nerves of the antrum the 

 phenomena described under I and II do not appear. Nor is 

 this the case when large pieces are removed from the semi- 

 circular canals without injuring the ampullae. 



IV. If the left auditory nerve of the animal is cut, the 



