OP THE CENTRAL COURSE. 



37 



Fi" 17. 



pation of the cochlea, all phenomena are shown that result from 

 extirpation of the labyrinth, but they are not so intense and are 

 much better restored. 



In the first days after the removal of the cochlea on both sides, 

 the animal is hardly to be 

 distinguished from one, in 

 which both labyrinths have 

 been removed. Trough in the 

 former case much more is 

 restored , I could not find a 

 great difference in the bearing 

 of rabbits after double-sided 

 removal either of the cochlea 

 or of the labyrinth during 

 the first week. 



In both cases sound-impres- 

 sions are perceived very badly 

 or not at all. The disturban- 

 ces of motion resulting from 

 double removal of the co- 

 chlea offer at first no diffe- 



11 n, i . i . A. Position of a non-operated rabbit. 



reilCe at all; alterWai'dS tlie D. Position of this rabbit after removal of both cochleae. 



difference is great, for two 



or three wrecks afterwards, the atonic symptoms recover. Only the 

 double operation is dangerous and badly supported. The difference 

 seems to be a difference in degree. All that becomes atonic after 

 extirpation of the labyrinth, becomes so likewise after extirpation 

 of the cochlea. One-sided cochlea-operations are followed by fast 

 recovery. Rolling never is obtained. 



5. The effects of the section of the dorsal secundary 

 tracts of the N. octavus. 



As soon as in a rabbit the section in the IV th ventricle, des- 

 cribed in the preceding chapter is produced, great care should be 

 taken to keep the head fixed , in order to prevent the animal 

 from damaging itself. For the lateral eye is jerked violently towards 

 the lower nasal can thus and the opposite eye towards the dorsal 

 (upper) canthus, the head turning at the same time with equal violence. 



The animal after being loosened from the operation-table, rolls, 

 the opposite upper extremity is hyper-abduced and extended and 

 the animal is kicking continually with this leg. The lateral fore-leg, 



