198 LECTURES ON THE CENTRAL NERVOUS SYSTEM. 



principal source in the outer side of the fleece. This, again, is 

 connected with the anterior cerebellar peduncle by the nucleus 

 dentatus cerebelli, which it surrounds. Thus, we can easily 

 imagine that the olivary body, the opposite restiforrn body, the 

 fleece, the anterior cerebellar peduncle and the red nucleus, 

 again of the opposite side, form a separate system of fibres. 

 Many observations, particularly those gained by experiments on 

 animals, go to show that this system is of great importance in 

 maintaining equilibrium. 



Many investigators, adopting Meynert's views, are of the 

 opinion that the cerebello-olivary tract is the continuation of the 

 fibres of the posterior columns, which pass, so they claim, into 

 the olivary body, and then emerge from it to reach the cerebel- 

 lum by way of the restiform body. We have, however, pre- 

 viously seen that the posterior columns, while they do indeed 

 reach the vicinity of the olivary bodies, through the arcuate 

 fibres, and even in many instances pass directly through them, 

 yet have nothing in common with the olivary fibres proper, but 

 terminate in the layer of the fillet. 



* * 



At those levels of the oblongata where the nucleus of the 

 vagus is situated, most of the fibres from the spinal cord have 

 already entered the restiform body. At this level, too, the 

 latter bas also received a part of the olivary tract. It lies in the 

 form of a thick bundle outside the last remnants of the posterior 

 columns. 



We have now reached the level at which we get a typical 

 section of the medulla oblongata. Let us, now that we have 

 met with the majority of the structures there present, take a 

 general view of the section as a whole. (See Fig. 120.) Many 

 points that are new can easily be added. 



In the ventral portion lie the pyramids. The large, tri- 

 angular field of dense, transversely-divided fibres just back of 

 them is the inter-olivary layer, the crossed prolongation of the 

 posterior-root fibres. The nuclei of the posterior columns lie 

 ^externally near the dorsal surface, still covered by a few nerve- 



