90 C. WINKLER. THE CENTRAL COURSE 



For this portio interim has strongly increased in these regions. Partly 

 because the nucleus of DEITERS has grown more extensive, partly because 

 more and more ventral root-fibres have entered, partly because more 

 and more fibres of the nuclei tecti cerebelli did find a place there. 



Together with the portio interim the ventral group of cells in 

 the dorsal nucleus is also increased and retiring laterally. It does 

 no longer form the ventral border of the principal group only, as 

 it was the case in distal sections, but it begins to border it also 

 laterally. At the same time the lateral group has become smaller 

 and is flowing together with the principal group. 



3 ly . This dorsal or principal group (Plate VII fig. 7 A II in b] 

 is very important. As soon as after rootsection, the ventral fibres 

 degenerate and with these the descending root of the ventral radix, 

 it is easily demonstrated that degenerated collaterals leaving per- 

 pendicularly the descending root-fibres penetrate into it (Plate V 

 fig. 9 and fig. 10). It is then very thickly specked with black granules. 



The descending root however accompanies in its distal course , 

 the ventral apex of the dorsal nucleus, and though it is situated 

 in the medio-ventral part of the portio interim , it is surrounded 

 by cells, forming a cellular nucleus, situated dorso-medially from 

 the root-fibres. 



The name of nucleus griseus radicis descendentis, given to it by 

 LEWANSDOWSKI , is a most fit one. These cells are of very different 

 size, but among them there are found many larger polygonal and 

 pyramidal ones, not so large as the cells in the nucleus of DEITERS, 

 a few of them reaching perhaps their size. 



Those cells, now are hardly distinguishable from the cells in the 

 ventral group of the nucleus dorsalis N. VIII. 



4 ly . The ventral group of cells (Plate VII fig. 7 A II in d), 

 though containing cells of different size, possess among smaller ones 

 many larger cells, a few of them also approaching the size of the 

 large cells of DEITERS. 



The ventral apex of the dorsal nucleus truly has quite another 

 structure as its basis, rather the same structure as the nucleus 

 griseus rami descendentis. Both receive a great quantity of root- 

 fibres of the descending root, and both are passed by root-fibres, 

 which must penetrate them, to reach the principal nucleus, as 

 well as the lateral nucleus. 



As soon as the tuberculum acusticum is gone laterally , and the 

 ventral root has entered, a part of its fibres are tending proximal ly 

 (as in Plate IV fig. 8 in a somewhat oblique frontal section is 

 seen). I have demonstrated that, in the same moment the ventral 



