114 C. WINKLER. THE CENTRAL COURSE 



After a short longitudinal and proximal course those fibres bend 

 dorsally into the lateral fillet (Plate XIX fig. 25 A, B). 



In frontal sections through this part of the pons, where the 

 pedunculus cerebelli superior begins leaving the cerebellum, the 

 situation is now characteristic enough. 



Dorsally and laterally of this peduncle the lateral fillet lays free 

 at the surface (fig. 25, C) and its most superficial layer is totally 

 degenerated. It here contains the ventral ascending spino-cerebellar 

 tract (GOWERS tract), which has just entered in this place after its 

 ventro-.lorsal path through the lateral lenmiscus, and leaves it soon 

 again to seek the nuclei tecti. 



But in these levels the degenerate layer round the ventral nucleus 

 lemnisci begins to change its longitudinal into a dorsal direction. 

 Embracing the nucleus ventralis lemnisci, its fibres never form the 

 most lateral layer of the lateral fillet, even not after the disappearance 

 of the antero-lateral spinal tract , but coursing towards the ventral 

 pole of the nucleus of the corp. quad, postic., they end in this 

 nucleus and I cannot trace them with certainty into the corpus 

 geniculatum mediale. 



These MONAKOW fibres, do not form a so sharply defined bundle 

 crossing they raphe, as they seem to do in the dog. Between the 

 fasc. long. post, and the place where the intermediary system passes, 

 there are found many crossing degenerate fibres, uniting themselves 

 in the degenerated area dorsally from the nucleus olivaris superior , 

 and in the surroundings of the nucleus ventralis lemnisci. 



In this manner there may now be distinguished, besides GowEBs' 

 tract , at least four different kinds of fibres in the contra-lateral fillet. 



1 rootfibres - - because some of them are degenerated after root- 

 section. They reach the fillet through the ventral and intermediary 

 system. 



2 e secondary fibres issued from the ventral nucleus - - because 

 a greater number of fibres degenerate if rootsection is combined 

 with section of they lateral ventral trunk. Those fibres , of course , 

 also pass through the ventral and intermediary system. 



3 e secundary fibres issued from the tuberculum acusticum - 

 because a still greater number of degenerate fibres is found there 

 if degeneration in MONAKOW'S fibres occurs. 



They pass through the stria medullaris as MONAKOW'S bundle 

 and enter in the dorsal layer of the oliva superior and in the sur- 

 roundings of the ventral nucleus lemnisci. 



4 e secundary fibres non degenerating after these operations and 

 probably issued for the greater part from the contra-lateral oliva 



