OF THE NERVUS OCTA.VUS. 145 



laris - - which I, anticipating, now call the dorsal systema of the 

 nervus octavus - - and by this nucleus itself (in distal regions) ; the 

 dorsal border of this area, in distal regions, is formed by the dor- 

 sal degenerated root-bundle and the angular nucleus. More proxi- 

 mally , this bundle having disappeared , there is found a new nucleus 

 in the dorso-lateral part of this area, between the nucleus parvo- 

 cellularis and the nucleus angularis. This nucleus is characterised 

 by the presence of very large cells and adopting WALLENBERG'S 

 nomenclature , I will call it the nucleus magnocellularis nervi octavi. 

 In this rather sharply defined area, in this portio interim of the 

 restiform body , different parts may be distinguished , which as they 

 comport differently to the root-fibres of the nervus octavus , may 

 have a different signification. 



l ly . The spinal fifth root and the fibres of the inferior cerebellar 

 peduncle are diverging during their proximal course, leaving be- 

 tween them a triangular area, wherein fibres are found, showing 

 an oblique direction in frontal sections. In this way , there appears 

 in the latero-ventral edge of the portion a field of triangular shape , 

 where after the removal of the labyrinth no degenerate fibres are 

 found. 



2 ly . Between the dorsal systema and the (fig. 26 A C) triangular 

 area described here, there is found another field. It is of almost 

 spherical shape (fig. 26 A E) and after removal of the labyrinth 

 several degenerated fibres - - queer-sectioned in frontal sections 

 are found in it. 



In distal regions this area is situated laterally from the nucleus 

 of the N. X , and it is resting upon the dorsal face of the spinal 

 root of the N. V (fig. 26 A). It retains its position in the ventro- 

 medial edge of the portio interna in proximal regions. But it is 

 soon bordered dorsally by the parvo-cellular and the magno-cellular 

 nuclei, and latero-ventrally by the nucleus N. VI. 



The degenerated longitudinal fibres, which in distal sections are 

 very numerous here, may gradually be traced issuing from the ventral 

 degenerated bundle of rootfibres (fig. 26 C and D). In this way 

 these fibres appear to be descending rootfibres, bending in a longi- 

 tudinal direction , and this area therefore may be compared with 

 the descending root. And as the ventral bundle contains chiefly, 

 though not exclusively ventral-root-fibres , it may be taken for gran- 

 ted that a few dorsal root-fibres, passing ventrally from the angular 

 nucleus participate to these descendent fibres. 



This area , that , conform to WALLENBERG'S nomenclature , may be- 

 called the ,,Acusticusfeld", thus contains a great many descending root- 



Verhand. Kon. Akad. v. Wetensch. (Tweede Sectie Dl. XIV). 10 



