Physiology. "A further Contribution concernimj the function oj 

 the Otolithic Apparatus." Bj Prof. R. Magnus and A. de Kleyn. 



(Communicated at the meeting of May 27, 1922). 



Im a previous publication') we demonstrated lliat when caviae are 

 centrifuged by Wittmaack's metliod, being- 1 hereby deprived of otolithic 

 membranes, the hibji-intli-reflexes resulting from position (tonic 

 labyrinth-reflexes on the extremities, "Labyrinth stell-reflexes", and 

 compensatory eye-positions) will disappear, but that, on the other 

 hand, the labyrinth-i-eflexes responding to movement (rotatory actions 

 and after-reactions on head and eyes and the reflexes on progression- 

 movements) will persist. It follows that the above position labyrinth- 

 reflexes are otolithic reflexes, since change of position of the head in 

 space does not enable us to elicit a change of the stimulation in the 

 sensory epithelium of the otolithic maculae, but does not at all 

 mean that the sensory epithelium cannot, under these circumstances, 

 be in a permanent condition of stimulation. It is a priori quite 

 possible that the sensory epithelium of the maculae, like that of the 

 retina, continually produces stimuli, whose magnitude, in the absence 

 of the removed otolithic membranes, can no more be altered by the 

 changes of position of the head in space. 



This conception was brought home to us by experiments to be 

 published afterwards. 



In order to go further into this subject we started from the 

 following consideration : 



The extirpation of one labyrinth in a normal animal brings about 

 an intricate complex of phenomena. A previous minute inquiry ') 

 into these phenomena enabled us to establish the following symptoms 

 as resulting directly from the unilateral extirpation of the otoliths 

 (membranes -J- sensory epithelium) or rather from the activity of 

 the otolithic organs on one side only : 



a. Rotation and flexion of the head towards the missing labyrinth. 



b. Eye-deviation : the eye on the side of the removed labyrinth, 

 deviating downwards, the other upwards.. 



1) These Proceedings, Vol. XXIII, p. 907. 

 *) Pflügers Archiv. 154. 178. (1913). 



