112 C. WINKLEE. THE CENTEAL COURSE 



ding spino-cerebellar tract (GowEn's tract) covers it. Besides the 

 fibres of these two tracts intermingle. Arrived at the spinal cord 

 (Plate XVIII tig. 22 II) it has found its place, ventro-laterally 

 from the forrnatio gelatinosa of the cornu posterior , its top is found 

 in the formatio reticularis of the cornu lateralis, and it leaves fibres 

 in the lateral horn of the grey spinal substance. 



Its degeneration is moderate , much more so than at the contra- 

 lateral side. There also however , this descendent tract is clearly 

 demonstrated by the black globules. 



Now there is not the least doubt that this tract is the same , 

 that has been described under many names , as rubro-spinal tract 

 (PAWLOW, VAN GEHUCHTEN), as aberrirendes Seitenstrangbiindel (Mo- 

 NAKOW) and others. As to its interpretation, it is allowed to presume 

 that the lesion made in a more proximal level , may have damaged, 

 the rubro-spinal tract in its course. But the most proximal end of 

 the lesion does not extend far enough to damage the issuing root 

 of the nervus trigeminus (Plate XVIII fig. 22 B) and neither the 

 incision, nor its white surroundings (Plate XVIII fig. 22 C, D 

 and F) transgress the fibres of the V th root. The non injured for- 

 matio gelatinosa and the non injured ventro-niedial fibres of the 

 V th root are separating in all levels the lesion from the presumed 

 situation of the rubro-spinal tract. Therefore there is no reason to 

 suppose an accidental lesion of this tract in its more proximal 

 course. Moreover it is degenerated likewise , through in a less 

 intensive degree , at the contra-lateral side. 



I therefore believe , we encounter here a third descendent tract, 

 that may be parallelised with the descendent tract of DEITERS and 

 the descending praedorsal tract. Only this tract is more clearly 

 degenerated after the section of the lateral trunk of the ventral 

 system than after the dorsal section. 



Besides I soon will have to discuss the further spinal course of 

 these three descending tracts, but before doing so there still remains to 

 be described another intermediary system that joins the ascendant 

 tract of the ventral system towards the corpus quadrigeminum pos- 

 terior after sectioning the dorsal system. 



The section of the dorsal system is not so difficult as that of 

 the ventral system. I have made it some twenty times, at one side 

 and on both sides. If made aseptic, it is without danger for the 

 animal. 



The incision made , after opening the membrana atlantico-occipitale, 

 has nearly always the same result. The tuberculum acusticum is 

 ablated, the radiation dorsally from the area ovalis is devided. The 



