OF THE NERYUS OCTAVUS. 149 



3 ly . Next to those fibres, other fibres leave the dorsal systema 

 to enter in both nuclei N. VI. In pigeons this nucleus, reaching 

 far ventrally, has a triangular shape and many fibres pass through 

 it in all directions. The homolateral nucleus receives degenerated 

 fibres from transverse dorsal fibres. In the contralateral nucleus 

 they chiefly enter through the fasciculus longitudinalis posterior. 



On both sides however the degeneration found in the VI th nuclei 

 is only slight. 



4 ly . The greater number of the degenerate fibres of the systema 

 dorsale enter in both fasciculi longitudinales posteriores and in the 

 fasciculi praedorsales. They bend there in longitudinal direction going 

 proximally and distally. 



a. The ascending longitudinal fibres of the fasciculus longitudi- 

 nalis posterior offer many interesting peculiarities. 



At the entrance of the octavus-roots evidently the contra-lateral 

 f. 1. p. is much more intensely degenerated than the homo-lateral 

 one. During its course next to the nucleus abducens fibres leave 

 it to provide this nucleus with a few fibres, but more fibres leave 

 it to gain the contra-lateral dorsal systema and the hilus of the 

 parvo-cellular nucleus. 



Proximal to the nucleus N. VI the fasc. long. post, has lost its 

 degenerate longitudinal fibres, almost completely on both sides. 



The proximo-dorsal shoots of the transverse dorsal fibres however, 

 have not yet ended in these levels here. From those both fasciculi 

 longitudinales posteriores soon receive new degenerate fibres. 



At the distal end of the IV th nucleus again both fasciculi have 

 degenerate fibres, obvious, though in small nnmber. They leave 

 fibres in those nuclei and again the number of degenerated fibres 

 is reduced, increasing at the distal end of the III th nucleus. 



In all these nuclei there exists a slight degeneration. On the other 

 hand the intermedullary root-fibres of these nuclei are covered with 

 large black granules. I am convinced that many of those globules 

 are situated in lymph-vessels and that they do not correspond with 

 degenerate nerve-fibres, but I also believe that others represent 

 degenerate fibres; as well as I am convinced, that in both fasc. 

 longitudinales posteriores, true degenerated fibres enter and leave 

 them again, because horizontal and sagittal sections demonstrate the 

 black globules, ranged in longitudinal rows, which may only be 

 interpreted as representants of degenerate fibres. 



In the preceeding paragraph I have discussed the difficulties, 

 which MARCHi-method offers in pigeons. 



It is impossible to interprete the true significance of all the 



