OF THE NERVUS OOTAVUS 77 



As I am convicted that fibres conducting sound must pass through 

 the corpus quadrigeminum posticum, and as the greater part of 

 the root-fibres to this nucleus originate in the intermedia! and 

 dorsal system , I believe that true auditory fibres must be sought 

 in transverse dorsal fibres. They chiefly are as we will see after- 

 wards MONAKOW'S transverse fibres , and MONAKOW is right to call 

 them the auditory" fibres. And on the other hand , the views 

 of FLECHSIG and other authors after him , holding that the ventral 

 system is to be compared with the root-fibres in the chiasma ner- 

 vorum opticorum , and that the corpus trapezoides forms a kind of 

 sciiii-decussatio of the fibres towards the corp. quadr. posticum 

 those views appear to me not sufficiently founded. The relations 

 of the primary auditory nuclei and the ventral tegmentum nuclei 

 with the lateral fillet are too complicated to allow such comparisons. 



1. Tlie rootjibres in the stratum latero-dorsale of tlie corpus restiforme. 



Tlte nucleus ventralis nervi octavi, the tuberculum acusticum and 



the systema dorsale nervi octavi. 



More complicated than the ventral system , is the dorsal system 

 of the eighth nerve. 



As we have seen in the preceeding paragraphs, the important 

 layer of fibres curving round the area ovalis of the corpus resti- 

 forme as a stratum latero-dorsale is not composed exclusively of 

 dorsal root-fibres. 



Dorsal fibres of the ventral root also participate in its formation, 

 as is demonstrated equally by Marchi-method after rootsection and 

 by the myelinisation-method. 



In sections through the medulla oblongata of the foetal rabbit 

 (Plate VI fig. 19 B, Plate XIII fig. 18 A and B) it is impos- 

 sible to determinate, from which of the two rootlets from the 

 dorsal root or from the intermediary rootlet going from the ventral 

 to the dorsal root - - originate the medullated fibres, entering in 

 the ventral nucleus and in the tuberculum acusticum. 



MARCHi-method may teach us more. After removal of the cochlea 

 there may be demonstrated an intense degeneration in the ventral 

 nucleus and in the tuberculum acusticum. After section of the nerve 

 there is a slight but strictly localisated increase of the degeneration 

 in tlie ventral nucleus , where as the degeneration in the tuberculum 

 acusticum is nearly as intensive in both cases. 



Therefore it may be established , that the greater part of the 

 dorsal root-fibres , degenerating after cochlea-removal are ending in 



