S. S. MAXWELL 



25 



1. Reflexes from the Labyrinth. — I have already spoken of the neces- 

 sity of avoiding any movement of the head at the moment of the 

 experiment. It would be quite possible, if labyrinth effects were 

 not taken into account, that the mechanical effect of the stroke used 

 as the stimulus would turn the head enough to excite a reflex from the 

 internal ear. I have often in the course of an experiment tried to see 

 how much and how fast the head must be turned in order to provoke 

 a labyrinthine response, and the amount has always been much great- 

 er than could be caused by the strongest contact stimulus employed. 

 But in order to avoid all possibility of error from this source I have 

 made experiments on a number of dogfish in which both labyrinths 



TABLE II. 



had been previously destroyed and have found the stereotropic 

 responses in no way altered. 



2. Tension oj Neck and Trunk Muscles. — The observation of Lyon- 

 that eye movements can be elicited by bending the body of the dogfish, 

 even after total destruction of the ears, can be easily repeated. Fin 

 movements can also be obtained in the same way. It was conceivable, 

 then, that the responses or some of them might have been due to 

 pressure on the side of the head inducing reflexes by changes of ten- 

 sion in the joints of the neck region. It was easy to test this also 



» Lyon, E. P., Compensatory motions in fishes. Am. J. Physiol., 1900--0I, 

 iv, 77. 



