OLf THE NE1TV US OCTAVTJS. I 2 3 



among the transverse dorsal fibres on the other side. There they 

 pass ventrally from the dorsal nucleus of the VIII th nerve towards 

 the opposite nucleus of DEITERS and bending distally, they follow 

 in the contra-lateral half of the oblongata, a perfectly symmetrical 

 course, forming a contra-lateral descending DEITERS tract, slightly 

 yet evidently degenerated, though not in such intensity as- the same- 

 sided tract. (Plate XVII fig. 20 E and E). These transverse dorsal 

 fibres I believe to originate in the destroyed nucleus of DEITERS 

 at the opposite side. 



However from the two tracts of DEITERS, as well from the 

 ascending, as from the descending, many other transverse fibres 

 originate. As is seen both in horizontal (Plate XVI fig. 20 D in 

 tr. DEIT. asc.) and in frontal sections (Plate XIX fig. 25 A E in 

 tr. DEIT. asc.) the ascending tracts send transverse fibres crossing 

 the raphe just ventrally from the fasc. long, posterior. As soon as, 

 in frontal sections, this tract approaching the fasciculus longitudinalis 

 posterior at its lateral side, has touched the grey matter round 

 the aquaeductus Sylvii, there are seen always fibres leaving it, pas- 

 sing the raphe. These fibres find their way to the lateral fillet. 



It has already been described that the lateral fillet here is com- 

 posed of several layers, from which two were degenerated. The 

 one, lateral from the nucleus ventralis lemnisci was formed by the 

 decussatio of MONAKOW fibres in more distal regions, the other, 

 also originated by these fibres did reach the dorsal layer of the 

 oliva superioi and increased with fibres arrived there from the 

 ventral and intermedial systems, formed the medial bundle in this 

 lateral fillet. 



Into this medial bundle (Plate XIX fig. 25 C and D) the dege- 

 nerated fibres above mentioned may be traced and this bundle is 

 increasing in its proximal course. 



These fibres , without any doubt being fibres going from the 

 ascending tract of DEITERS to the medial bundle of the contra- 

 lateral fillet , may be interpreted as more proximal situated MONA- 

 KOVV'S fibres and at the nucleus of the IV th nerve , where the 

 ascending tract approaches its end, (it .passes near to the nucleus 

 of DARKSCHEWITSCH , but gives only a few fibres into it) the most 

 proximal fibres of this system pass the raphe to the medial bundle 

 of the lateral fillet. 



In this way the tract described by PROBST as a commissure be- 

 tween the fillets , passing ventrally before the nucleus IV , may be 

 a part of this system. 



The relations between the descending tract of DEITERS and trans- 



