OP THE NERVUS OCTAVUS. 49 



the bipolar nerve-cells in the ganglion spirale cochleae are the 

 medullated fibres composing the cochlear nerve and this nerve 

 may be continued in the lateral (dorsal or distal) root of the ner- 

 vns octavus. 



Nevertheless it must be admitted that there exists a little ner- 

 vous branch , gathering the fibres from the macula sacculi in a 

 small proper ganglion. The central prolongations of the cells in 

 this ganglion may also be traced in the cochlear nerve (RETZIUS, 

 SCHWALKE a. o.). 



On the other hand the macula utriculi and the cristae ampullae 

 may receive the centrifugal prolongations of the bipolar cells 

 composing the ganglion plexiforme Scarpae. In rabbits these cells 

 are spread in the course of the vestibular nerve , and their centri- 

 petal prolongations pass through this nerve in the medial (ventral 

 or proximal) root of the nervus octavus. 



Both nerves together therefore are forming the nervus octavus, 

 but, as is argued, cochlear and vestibular nerve are different ner- 

 ves, different in structure, as well as in function. Their structure 

 is different in many regards. 



Firstly their relation to the periferical ganglia is not quite the same. 



The ganglion spirale lies concealed in the lamina ossea of the 

 cochlea. Therefore the cochlear-nerve , in its traject through the 

 meatus auditorius interims, may be compared with a spinal root. 



Not so the vestibular nerve. The cells are spread along this nerve 

 and the so called ganglion vestibulare nearly touches the medulla 

 oblongata. The vestibular nerve consequently may be partly com- 

 pared with a spinal root, but partly also with a periferical nerve. 



The degenerations in the nervus octavus after removal of the 

 labyrinth may be influenced by this anatomical peculiarity. 



For the removal of the cochlea includes necessarily the removal 

 of the ganglion spirale and it is directly comparable with a root- 

 section. 



The removal of the contents of the vestibulum and even the 

 section of the vestibular nerve in the meatus auditorius is not 

 necessarily combined with a complete removal of the ganglion 

 vestibulare. To do this, the vestibular nerve should be torn out 

 and broken close to its entrance in the medulla oblongata, and it 

 is hardly possible to do so , without lesion of the medulla. 



But only the latter operation may be compared with a complete 

 root-section. The removal of the vestibulum and the section of the 

 vestibular nerve are operations partly comparable with a root- 

 section , partly with the section of a periferical nerve. 



Verhand. Kon. Akad. v. Wetenscli. (Tweede Sectie DI. XIV). 4 



