82 



Scientific Proceedings (52). 



Stimulation of the otic labyrinth in a number of different ways, 

 including rotation about a particular axis of the head, evokes 

 movements of the eyes, and sensations of apparent movement of 

 external objects or of one's own body, or both. The movement 

 of the eyes is slow to the stimulated side if a weak stimulus is 

 used, and slow to the opposite side if a strong stimulus is applied. 1 

 Here also the real or apparent movement of external objects is in 

 the direction of the slow deviation of the eyes, and the apparent 

 passive movement of the body, or the real passive movement, if 

 rotation occurs, is in the direction of the quick movement of the 

 eyes, if it occurs. This quick movement of the eyes is lacking in 

 some lower forms, such as the turtle. 



When, by any means of labyrinthine stimulation, sensation of 

 apparent (passive) movement of the body is produced in an animal 

 at rest, the active compensatory movement of the animal is 

 opposite in direction to that of the apparent movement of the 

 body, and is in the direction of the slow movement of the eyes. 

 This is the basis of the explanation of the fact, observed clinically, 

 that patients with labyrinthine lesions fall or make other body 

 movements in the direction of the slow deviation of the eyes, a 

 relationship not previously sufficiently emphasized. 



In electrical stimulation of the labyrinth by the direct current, 

 the animal (turtle) moves toward the side on which the anode 

 is placed. Reversing the direction of the current changes the 

 direction of movement of the animal. 



We may give a description of the passive movements, either 

 real or apparent, and the active or compensatory movements of 

 the body, under these various conditions, in terms of eye move- 

 ments by the statement that the passive movements are in the 

 direction of the quick movement of the eyes, and the active 

 compensatory movements are in the direction of the slow devia- 

 tion of the eyes. 



'Wilson and Pike, Phil. Trans. Royal Society, London, Series B, 1912, Vol. 203, 

 p. I3S- 



