OF THE NERVUS OCTAVUS. 135 



II ITS MEDIAL TRUNK however receives by far the larger portion 

 of its fibres. They enter dorsally from the spinal V th root, between 

 it and the oval area C. R., and dorsally resting upon its medial 

 end they bend distally (the descending root) and proximally (the 

 ascending root). These fibres unite with dorsal and ventral root- 

 fibres of the dorsal systema which have curvated round the corpus 

 restiforme. As the restiforni body retires into the cerebellum dorsal 

 and medial trunk are no longer separated and form a single trunk. 



In the ventral trunk small cells are intercalated (uucl. proprius 

 radio, ventr.). 



The descending rootfibres are accompanied by smaller and larger 

 cells (the nucleus griseus radicis descendentis) united to the cells 

 of the medial apex of the nucleus dorsalis. 



This nucleus continues to accompany the ascending root and is 

 called there the nucleus of BECHTEREW. The ascending and the 

 descending root give rootfibres (far the greater part being ventral- 

 rootfibres, the smaller part dorsal rootfibres) to many nuclei. 



1. ventral rootfibres to the nuclei tecti cerebelli. 



2. ventral root-Jibres to the nucleus of BECHTEREW and to the 

 nucleus (/rise us radicis descendentis. 



3. ventral rootfibres to all tlte cells of the dor sal nucleus N. VIII. 

 In all these nuclei small cells are found to intercalate rootfibres 



with the large cells of UEITERS nucleus, which have no direct 

 relations with any rootfibres. 



4. ventral rootfibres among the dorsal transverse fibres, taking 

 the way described in the schema of the dorsal root-fibres but 

 providing now to a mere considerable degree the III th , the IV th 

 and the VI th same-sided nuclei, the contralateral VI th nucleus and 

 the beginning of the tractus DEITEHS descendens and the tractus 

 praedorsalis. 



III ITS VENTRAL TRUNK 



receives fibres taking the course described by the dorsal root-fibres. 



THH ASCENDING FIBRES OF THE SECUNDARY SYSTEMS 

 OF THE NERVUS OCTAVUS. 



(Schema C). 



Degeneration and atrophy after sections through the central 

 system in rabbits and comparison with the foetal central system 

 have taught, that from the nucleus ventralis, the tuberculmn acus- 

 ticum and DEITERS nucleus (-J-- large cells of the nucleus griseus 



