OF THE NERVUS OCTAVUS. 129 



fig. 20 and in the ventral section of fig. 22 the samesided dege- 

 neration in the rubro-spinal tract was very intense, in the double- 

 sided it was only slight. I doubt, that the rubro-spinal path should 

 have been damaged, but if in the medio-dorsal parts of the lateral 

 fillet fibres are found, issuing from the c. quadr. posticum (or 

 through the ventral fibre-layers of this ganglion from the corpus 

 geniculatum or from the thalamus) and degenerating in descendent 

 direction, it might have been possible, that, in the extensive dorsal 

 section of fig. 20, a division of those fibres has been the cause of 

 the intensive degeneration found in the rubro-spinal path. 



Now as I find without lesion of the fillet a slight (Plate XXI 

 fig. 25 M O) or even a more intense (Plate XVIII fig. 22 G H) 

 degeneration in this tract (dorsally situated in the cord) according 

 to dorsal or ventral section of the secundary systemata, I conclude 

 that this tract also receives any fibres through the secundary octavus- 

 systems and chiefly from the ventral systema. Here also the dege- 

 neration is found on both sides, but chiefly homolateral. 



In this way I believe that the secundary octa\ 7 us-systems are 

 sending fibres to the medulla chiefly on the same side, along three 

 ways. There are to distinguish l ly a praedorsal system or in refe- 

 rence to the cord, a ventral octavo-spinal way, 2 ly a tractus DEITERS 

 descendens, or in reference to the cord, a lateral octavo-spinal way, 

 3 ly a smaller path in the ,,aberrirendes Seitenstrangbiindel" or in 

 reference to the cord a dorsal octavo-spinal way. 



5. SUMMARY OF RESULTS. 



I will close this chapter by giving the schemata, according to 

 the results of these anatomical researches. 



After removal of the cochlea, there is found an important dege- 

 neration in the dorsal root, the extra-medullar part of the ventral 

 root however is found without degeneration. 



After removal of the labyrinth, both roots are brought to dege- 

 neration, but a still more intense one takes place in the extra- 

 medullar part of the dorsal root than after cochlea-removal. 



Both roots, after having entered the oblongata, divide in three 

 parts, a dorsal, a medial and a ventral trunk. 



The dorsal root sends by far the larger part of its fibres into 

 the dorsal trunk (stratum latero-dorsale C. R.), only a few fibres 

 into the medial trunk, and also some fibres into the ventral trunk. 



The ventral root sends the majority of its fibres into the medial 

 trunk between the spinal root of the V th nerve and the area ovalis 



Verhand. Ron. Akad. v. Wetenscli. (Tweede Sectie Dl. XIV). 9 



