OF THE NERYUS OCTAVUS. 105 



nucleus (Plate XIV fig. 14 B, Plate XI fig. 16 K and L), 

 following the path of the ascending tract of DEITERS. I will soon 

 describe this bundle in a more minute way. 



In this way the dorsal transverse root-fibres have relations with 

 the nucleus N. VI, the nucleus N, IV and the distal end of the 

 nucleus N. Ill of the same side and with the nucleus N. VI of 

 the opposite side. 



In this way the dorsal system of transverse rootfibres may be 

 traced to its endings, towards all motor nuclei of the eye on the 

 same side, towards the opposite nucleus of the VI lh nerve, in the 

 fasciculi longitudinal es posteriores and in the area of the descendent 

 tractus of DEITERS. 



It remains however a remarkable fact, that after rootsection 

 hardly any degenerated fibres or even none at all are found cros- 

 sing the raphe, between the layer of dorsal transverse fibres and 

 the layer of intermedial transverse fibres. 



The so called auditory fibres of MONAKOW appear free from dege- 

 neration after root-section as likewise they are not all myelinisated 

 in the elder foetal animal. 



3. THE SECUNDARY SYSTEMS OF THE NERVUS OCTAVUS. 



Iii using Marchi-method, after experimental lesions upon root-fibres, 

 it should always be kept in mind, that together with the enormous 

 advantages peculiar to this method, there also arise dangers, as 

 soon as single degenerated fibres are to be traced with its aid. 



It is possible, even probable, that an experimentally produced 

 degeneration in a system of rootfibres, is not stopped by the first 

 nucleus, which is intercalated in its course. 



As well as by GUDDEN'S method -- experimenting on young born 

 animals and studying their central system several months after the 

 lesion may be demonstrated the loss or the atrophy in the 



first nucleus and together with it the atrophy of the following 

 system, Marchi-method - used a fortnight after the experimental 

 lesion may show a slight degeneration in the secundary 



system. 



As soon as scarcely degenerated fibres are found with Marchi- 

 method in a presumed secundary system , three possibilities exist to 

 account for their presence there. 



The first is to suppose , that true root-fibres pass without any 

 interruption through the nucleus in the secundary system. L have 

 accepted this interpretation when an important number of fibres 



