LABYRINTH AND EQUILIBRIUM. 

 III. The Mechanism of the Static Functions of the Labyrinth. 



By S. S. maxwell. 



{From the Rudolph Spreckels Physiological Laboratory, University of California, 

 Berkeley, and the Marine Biological Laboratory, Woods Hole.) 



(Received for publication, September 4, 1920.) 



The Static Functions of the Ampullce. 



In a preceding paper^ I have shown that removal of the otolith 

 organs from the labyrinth of the dogfish does not destroy the static 

 functions; that, on the contrary, the compensatory changes of posi- 

 tion of the eyes and fins occur when the animal so operated is tilted 

 out of the normal or primary position ; and that if the animal is held 

 in the abnormal position permanently the compensatory positions of 

 the eyes and fins are also retained permanently. I have also pointed 

 out that the stimuli for the maintenance of these compensatory posi- 

 tions do arise from the labyrinth; that they are not affected by the 

 exclusion of other sensory stimuli; but that they disappear at once 

 when the remaining parts of the labyrinth are destroyed. I also 

 proved that rotations around the body axes excite the dynamic re- 

 sponses through changes of tension on the ampullae due to the inertia 

 of the vestibular contents, and not through the production of currents 

 in the semicircular canals. I wish now to show that the same mech- 

 anism which excites the ampullae to the exercise of their dynamic 

 functions serves also to produce their static effects. 



While an animal is undergoing rotation around a body axis there 

 is brought about through inertia a displacement of the contents of the 

 vestibule, and this displacement and the consequent change of tension 

 acts as a stimulus. If on cessation of the movement of rotation the 



^ Maxwell, S. S., Labyrinth and equilibrium. I. A comparison of the effect 

 of removal of the otolith organs and of the semicircular canals, /. Gen. Physiol., 

 1919-20, ii, 123. 



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