OF THE NEHVUS OCTA.VUS. 93 



The nucleus of BETTERS disappears when the oval area leaves 

 the medulla and has become the inferior peduncle of the cere- 

 bellum, and as we will afterwards have much to do as well with 

 this nucleus as with its position in the latero-dorsal quadrant of the 

 portio interna, I memorate these long known facts here. 



Kootsection of the nervus octavus now enables us to demonstrate 

 other fields in the portio interna and divides it in degenerating 

 and non degenerating portions. 



After root-section, the medial octavus-trunk, the medial fibres of 

 the ventral root, nearly totally degenerate. 



They enter between oval area and spinal root of the V th nerve, 

 closely adossed dorsally to the latter (Plate VIII fig. 15 N. 9) 

 and having reached the medio-ventral edge of the portio interna , 

 just there, where the ventral apex of the dorsal auditory nucleus, 

 the medial edge of the V th spinal root, and the portio interna meet, 

 a great many of them bend downward in an angle of 90. 



This is the descending octavus-root, the degeneration of which 

 after rootsection is shown very clearly in horizontal sections. (Plate V 

 fig. 9). Kite X fig. 16 I. Plate XIV fig. 14 A), but is also easily dis- 

 tinguished in frontal sections, as an area of degenerated fibres, 

 situated in the medio-ventral quadrant of the portio interna (Plate VIII 

 fig. 15 N. 8, 7, 6, 5, 4). 



This area, composed of separated nerve-bundles, showing many 

 degenerated fibres between non degenerated ones, may be traced 

 until the proximal end of the nuclei of the posterior columns. 



Now, they are not exclusively medial root-fibres of the ventral root, 

 which compose this descendent tract, though they may form the 

 greater part of it. 



After removal of the cochlea there are also seen some fibres 

 degenerating in it. These are firstly the few fibres running from 

 the dorsal root into the medial trunk, but they mostly are belon- 

 ging to the fibres of the stratum latero-dorsale , which have curved 

 round the oval area, and passing obliquely through the nucleus of 

 DEITERS also reach the medio-ventral edge of the portio interna. 



These are the fibres, not very many, but yet demonstrable, which 

 from the dorsal root do enter in the radix descendens. They never 

 after cochlea-removal may be traced so far as to the nucleus of 

 the X th nerve. 



But after root-section, the number of degenerate fibres in the 

 inner layer of the stratum latero-dorsale being increased, not only 

 the intermedial system is degenerated in a more important degree, 

 but also many of those fibres, penetrating through the area ovalis, 



