OF THE NEKVUS OCTAVTJS. 103 



vestibulospinalis is found. They also bend distally in longitudinal 

 direction and are represented by only a few fibres. In frontal 

 sections distally from this nucleus, a few black granules are scattered 

 here and there, within the area of this tract (Plate VIII fig. 15. 

 N. 5 N. 1) and in horizontal sections (Plate X fig. 16 F) there 

 are found a few longitudinal fibres degenerated. These fibres 

 may become important, because they are found in the same area, 

 where a considerable secundary system (already myelinisated in the 

 elder foetus) will soon be demonstrated. Indeed I believe that a 

 small number of rootfibres bends down, without interruption in 

 the tract us DEITERS descending and may be traced towards the 

 beginning of the spinal cord. 



But the few fibres, that in ventral direction deviate in the for- 

 matio reticularis, do not much enfeeble the transversal dorsal fibres. 

 Moreover these fibres have got a considerable increase in proximal 

 regions from the straight entering ventral fibres and from the 

 ascending root. They pursue their way, through the ventral apex 

 of the dorsal nucleus, along the ventral border of the nucleus of 

 the VI th nerve, giving collaterals to the principal and .ventral cells 

 of the dorsal nucleus and to the sixth nucleus. They still form a 

 rather important bundle, as they reach the fasciculus longitudinalis 

 posterior, and pass the raphe to send fibres into the opposite sixth 

 nucleus, which is found blackened with globules, as well as that 

 of the same side. 



But at their passing the raphe a sufficient quantity of degenerated 

 fibres, are bending in longitudinal direction to become ascending 

 as well as descending fibres in the fasciculus longitudinalis posterior 

 on both sides. 



At first, more degenerate fibres are found in the opposite than 

 in the hornolateral fasc. longit. post, they go distally and proxi- 

 mal ly, providing the nucleus of the sixth nerve on both sides. 



In this way the two nuclei of the sixth nerve, receive fibres of 

 the dorsal systema. That of the same side recives them, l e from 

 the descendent root (Plate XIV fig. 14 A), 2 e from the fasc. long, 

 post. (Plate VIII fig. 15 N. 8 N. 11), that of the oppo- 

 site side only from the fasc. long, post., but, the number of 

 degenerate fibres in the opposite f. 1. p. being greater than in 

 that at the same side, the innervation of the two nuclei may not 

 much differ. 



Now a certain number of those fibres may be traced far more 

 distally than the nucleus of the VI th (fig. 15* N. 5 N. 1). They 

 are longitudinal fibres but have at the same time a slight inclination 



