257 



As secondary results from the rotation of the head sub a appear 

 change of posture of the whole bod}, difference of tonus in the 

 extremities, rolling movements etc. 



We do not know as jet which part of the labyrinth is responsible 

 for a transitory difference of tonus in the extremities, which persists 

 also with the head in the normal position towards the trunk. This 

 symptom has, therefore, to be left out of consideration in the 

 following discussion. 



On the basis of these findings we performed the following expe- 

 riments : 



Caviae were centrifuged after the familiar method of Wittmaack. 

 Now only those animals were used for further experimentation in 

 which clinically all labyrinth-reflexes of position disappeared and all 

 movement-reflexes maintained themselves, or, in other words, animals 

 in which it could be expected thatall the otoliths had been completely 

 detached on either side. 



In order to eliminate as much as possible a stimulating, or 

 paralysing influence of the removal itself on the sensory epithelium, 

 the animals were regularly examined and the experiment proper 

 was started only fi-om 7 to 9 days after the centrifugation. 



In this procedure about 0.1 cc. of a 5°/,, cocain solution was 

 injected unilaterally through the ear-drum into the middle-ear, in 

 order to paralyse the whole labyrinth on that side. 



If it should now appear that, after the removal of the otoliths, 

 the sensory epithelium of the maculae was not in a condition 

 of stimulation, it could be expected that no phenomena should reveal 

 themselves after the cocain injection, with the exception only of a 

 nystagmus consequent on the elimination of the semicircular canals 

 on the injected side. 



If, however, there is indeed, after the removal of the otoliths a 

 stimulation in the sensory epithelium of the maculae, we may look 

 for asymmetrical phenomena after the cocain-injection, since at the 

 injected side the sensory epithelium is completely paralysed and there 

 is a constant condition of stimulation at the other side. 



After the cocain-injection a rotation of the head towards the 

 injected side (^'Grunddrehung" ; ulriculus) and an eye-deviation (eye 

 at the injected side down, the other eye upwards; sacculus.) may 

 llien be expected, i. e. phenomena agreeing with those appearing in 

 normal animals, if ipsilaterally the labyrinth is paralysed through 

 extirpation or through injection. With this difference, however, that 

 the phenomena in animals with removed otoliths do not vary, as 

 is the case in normal animals after unilateral extirpation of the 



