76 C. WINKLER. THE CENTRAL COURSE 



separated from them (Plate XI fig. 16 K N, Plate XIV and 

 Plate XV, fig. 14 A E). The} 7 embrace the nucleus ventralis 

 lemnisci, their number is augmented by root-fibres originating in 

 dorsal transverse fibres and as soon as the cerebellar fibres leave 

 the tegmentuin to reach the nuclei tecti , (Plate XV fig. 14 D 

 and E) the fibres to the corp. quadrigeminum posticum remain. 



Though degenerating on both sides after one-sided root-section 

 the greater quantity of these rootfibres is found on the opposite side. 



After root-section of the VIII th nerve therefore also ascendent 

 tracts of root-fibres may be demonstrated with MARCHI. method. 

 There are two. 



Rootfibres of the N. octavus are found in the ,,ascending ventral 

 spino-cerebellar tracts" to the nuclei tecti mediales, especially in the 

 homolateral tract. 



Rootfibres of the N. octavus are also found in the lateral fillet 

 to both corpora quadrigemina postica but chiefly in the lateral 

 fillet of the opposite side. I repeat , that after rootsection , the 

 number of degenerated fibres in those tracts is not very considerable, 

 though they are evident. 



After the removal of the cochlea the number is again diminished. 

 Then they must be sought for attentively , and I believe that 

 Marchi-method in such cases has nearly reached its utmost limits. 

 For, even in a fortnight, the black granules, characterizing the 

 degenerated fibres, are spread in the neighbourhood if there exists 

 a localised degeneration , and the number found in the two des- 

 cribed tracts after cochlea removal is very limited , especially in 

 the cerebellar tract. None the less I am convinced that even after 

 cochlea removal they may be demonstrated. 



I therefore agree completely with HELD, who has long since 

 defended the view , that primary fibres penetrate in all the secun- 

 dary systems and accompany them, but I also think that the num- 

 ber of root-fibres entering in secundary systems is very different in 

 different animals. 



It is here perhaps the place to remark, how interesting it is, 

 that the very great number of root-fibres existing in the ventral 

 and intermedia! system , is reduced to a very small quantity in the 

 lateral fillet to the corpus quadrigeminum. Indeed , if they were 

 not augmented considerably with rootfibres from the dorsal system, 

 rootfibres to the corpus quadrigeminum would be rare. 



There fore I believe that the root-fibres in the ventral system 

 (the corpus trapezoides) have chiefly the significance to intercalate the 

 ventral tegrnentum nuclei in the reflex-system of the nervus octavus. 



