62 C. WINKLEK. THE CENTRAL COURSE 



zoides, that pass along the ventral margin of the medulla oblon- 

 gata and belong to primary or secondary auditory systems ,,the 

 systema ventrale nervi octavi". I have already mentioned that after 

 sectioning the eighth nerve , thick fibres as well as small fibres are 

 found degenerated among the transversal fibres of the corpus tra- 

 pezoides. 



The thick fibres principally originate from the ventral root, but 

 they are also found after the removal of the cochlea in a smaller 

 quantity (Plate I, fig. la and \b. Plate II fig. 2). 



The degenerated thick fibres have their proper situation and are 

 found in the most ventral layers of the corpus trapezoides. At the 

 ventral margin of the medulla oblongata, ventrally only covered 

 by the free anterior pyramidal tract , they pass through the raphe 

 (see Plate VIII and IX fig. 15. N. 11, 12, 13, 14) and end 

 in both nuclei trapezoides. 



Only a small quantity ends in this nucleus of the same side in 

 its latero-dorsal edge. By far the greater part of them reaches, 

 after having crossed the raphe, the opposite trapezoid nucleus, 

 entering at its medial hilus (Plate II fig. 2 , Plate VIII and IX 

 fig. 15, N. 11, 12, 13, 14, fig. 1G, A and B). 



In frontal sections through the capital parts of the corpus trape- 

 zoides , those degenerated fibres , demonstrated with their black 

 granules by the MARcm-method seem to form a garland (Plate VIII 

 and IX, fig. 15 N. 11 14) thrown round the same-sided trapezoid 

 nucleus and held at its top by the opposite one. 



In the systema ventrale nervi octavi therefore there may be 

 distinguished. 1 c thick root-fibres from both roots to the nuclei trape- 

 zoides, especially to the opposite nucleus, situated among the most 

 ventral transversal fibres of the corpus trapezoides and forming therein 

 the stratum ventrale or the stratum a of the corpus trapezoides. 



But fibres of small calibre are also found degenerated among the 

 transverse fibres of the corpus trapezoides , as well after the removal 

 of the cochlea as after sectioning the eighth nerve (Plate I fig. 1/7, 

 and Ib, Plate II fig. 2, Plate IX fig. 16 B and C). 



They are found in deeper, more dorsal layers of it, pass close 

 to the lateral facies of the spinal root of the nervus V and along 

 to the facial nucleus. A few fibres terminate in the latter nucleus. I 

 certainly accord with HELD in this regard (Plate I fig. la and 

 Ib , Plate IX fig. 16 C and D) , but I will come back on this 

 question , when discussing the endings of the fibres of HELD (of 

 the systema intermedium) in the VII th nucleus. 



After their passage ventrally from the facial nucleus, the majority 



