()0 C. WINKLER. THE CENTRAL COURSE 



acusticum. VAN GEHUCHTEN therefore thinks erroneous the differing 

 results of TRICOMI-ALLEGRA, who, experimenting principally on rab- 

 bits, assumes root-fibres entering the corpus trapezoides, and the 

 cause of his error is by VAN GEHUCHTEN presumed to be a lesion 

 of the facial nerve. 



This nerve indeed crosses the area of operation and if injured, 

 for instance by a slight traction , the lesion may be sufficient to 

 cause a degeneration of the transversal fibres of the corpus trapezoides. 



Moreover, there are, with the Marchi-method , often found some 

 black stained granules at the entrance of the VTI Ul nerve and in 

 its root-fibres. 



Therefore, as argues VAN GEHUCHTEN, the slight tractions or 

 other lesions of the facial nerve during the operation are the cause 

 of the degenerated transversal fibres in the corpus trapezoides and 

 the passage of auditory root-fibres therein is not proved. 



Now I have already mentioned that Marchi-method offers dan- 

 gers. One of these is, that the black granules - - even within a 

 few days after their appearance - - are carried away by the lymph- 

 current and that the roots, leaving the central systems, may be 

 reckoned among the out- ways of the lymph-circulation. Indeed, black 

 granules are often found there, where roots leave the system , and 

 if a degeneration exists in the corpus trapezoides, they must be 

 found at the issue of the facial nerve. 



But if the presence of some granules at the entrance of the 

 facial root-fibres is used - - as is done by VAN GEHUCHTEN - to 

 prove a lesion of the facial nerve I cannot entirely accept this 

 view. They necessarily must be found there after each degeneration 

 in the corp. trapezoides. And their presence in roots after degene- 

 rations in the central system only proves that Marchi-method is not 

 a sovereign method and needs to be controlled. But in the 

 preceding paragraph , I have established the fact that the myelini- 

 sation also gives arguments in favour of the opinion that root-fibres 

 of the Vlll lh nerve directly enter into the transversal fibres of the 

 corpus trapezoides (Plate XIII fig. 19 B). Another experiment 

 however may be taken , that demonstrates clearly the passage from 

 the rootfibres in the corpus trapezoides , as well from the dorsal 

 ar from the ventral root. 



In a new-born rabbit, the atlanto-occipital membrane may be 

 opened in order to divide the lateral part of the medulla oblon- 

 gata in such a manner that the ventral auditory nucleus and the 

 tuberculuin acusticum have lost all connections with the medulla. 

 This operation may be done with a single draught of the thin knife, 



