58 C. WINKLER. THE CENTRAL COURSE 



the auditory-nerve gives a very decisive answer in favour of the 

 questions treated here. 



Only it ought to be kept in mind that the ordinarily used fron- 

 tal series of sections are not very apt to demonstrate the course 

 of the root-fibres. 



In a newborn rabbit it is nearly impossible (f. i. fig. 17. A 

 and B on Plate XTI, and fig.' 5 on Plate I) to disentangle the fibres 

 mixed together at the entrance of the two auditory roots. There 

 the fibres of roots and of the corpus trapezoides are all medullated 

 and mixed together in an inextricable mass. 



Much easier the question is in sagittal sections. There the rela- 

 tion between the two roots and the corpus trapezoides is very clear 

 (Plate VI fig. 19 A B and Plate XIII fig. 18 A D). Simpler 

 as it is given in Plate VI fig. 1 9 A and in fig. 1 8 A on Plate 

 XIII, the relation between the two roots may be hardly demon- 

 strated. In fig. 18 A the section touches the superficial layer of 

 the medulla oblongata. The entrance of the nervus trigeminus (N. V) 

 is found most proximally. The proximal (medial or ventral) root of 

 the VIII th nerve with its thick fibres is distinctly separated from 

 the distal (dorsal or lateral) root of the VIII th nerve, having small 

 fibres. But immediately it is seen that an interrnedial rootlet passes 

 from the ventral towards the dorsal root (Plate VI fig. 19 A and 

 Plate XIII fig. 18 A r. interni). 



By means of this intermedial rootlet fibres are passing from the 

 ventral root into the stratum latero-dorsale, as it is. found between 

 the ventral auditory nucleus and tuberculum (Plate VI fig. 19 B 

 and Plate XIII fig. 18 B). And in Plate XIII fig. 18 C it is 

 clearly demonstrated that fibres of the ventral root, now found 

 between the spinal root of the N. V. and the restiforin body, 

 perforate the latter (its oval area) to reach the stratum latero-dorsale. 

 Those fibres, penetrating the corpus restiforme, may be found in 

 all sagittal sections until the portio interim of the corpus restiforme 

 is reached, at that moment a new bundle is found, close to the 

 most medial limit of the oval area in the most lateral part of the 

 portio interna of the restiforin body. This latter bundle (fig. 181) 

 on Plate XIII in h. or HELD'S interm. system) leaves the stratum 

 latero-dorsale, and crossing the forma tio gelatinosa of the spinal 

 trigeminus-root , finds its way as well to the systema intermedium 

 as even towards the corpus trapezoides. In a proximal situation to 

 this bundle the bundle of HELD - - but medially from the oval 

 area, communicating fibres from the ventral root to the latero- 

 dorsal layer of the restiforin body are still always to be seen , and 



