OP THE NERVUS OCTAVUS. 61 



without damaging the auditory root-fibres or with only a partial 

 lesion of them. 



The operation may seem difficult , but as a fact it is much sim- 

 pler than it appears. In my possession are at least three series of 

 post-mortem verified specimina wherein such an operation has suc- 

 ceeded. 



Now one of these relates to an animal killed six months after 

 such an operation. As I will show afterwards , in consequence of 

 it an important atrophy of the corpus trapezoides was produced, 

 as indeed was our purpose. The latter is now reduced to the fibres 

 originating from the rootfibres, and to the fibres, originating from 

 the inedio-ventral part of the ventral auditory nucleus , that cannot 

 be removed from the medulla oblongata, if the roots shall be spared. 



Now the relations have become very transparent. Without any 

 difficulty , the normal fibres of the dorsal , as well as of the ven- 

 tral root, now may be followed in the transversal fibres of the 

 reduced corpus trapezoides (as fig. 12 on Plate XXI demonstrate, 

 where as fig. 28 A E on Plate XXI show the extension of the 

 lesion , wich is found as a port-mortem defect). 



Therefore, as to my experience, it cannot be doubted that 

 auditory root-fibres enter without ganglionic interruption between 

 the transversal fibres of the trapezoid body. On the other hand 

 I must concede to VAN GEHUCHTEN that in other animals - - for 

 instance in dogs I found the extirpation of the cochlea not 



always followed by degenerations in the ventral systema, at least 

 within a fortnight. Indeed I believe , that the difference between 

 the root-systems and the secundary systems is not a very essential 

 one. Not only , I am convinced with HELD , that primary (root-)fibres 

 find their way in all the secundary systems , but I think even , 

 that a primary system may be replaced by a secundary system and 

 vice versa. 



In rabbits however I argue that the Marchi-method of degene- 

 ration, the myelinisation and GUDDEN'S atrophy-method all are con- 

 cordant in the demonstration , that root-fbres of both roots enter 

 directly into the corpus trapezoides or better in the so-called ^systema 

 ventrale nervi octavi" . 



e. The systema ventrale nervi octavi. The situation of the 

 root-fibres in this system and their further course. 



With a small variation from the nomenclature given by EDINGER. 

 I hence, forth will call the transversal fibres in the corpus trape- 



