338 ANATOMY OF THE CENTRAL NEEYOUS SYSTEM. 



to the nerve-trunks. But recently doubt has arisen regarding it, since the 

 tract has not \\'ith perfect certainty been traced beyond the nucleus. At 

 any rate, it is wiser at present to designate the system as tr. cerebellaris 

 acustici, etc., and not as the direct sensory cerebellar tract. In Fig. 212, 

 from a seven-month human fetus, the reader will recognize a part of the 

 tract which passes into the X. trigeminus. 



II. THE COHPUS BESTIFOEME PEOPEE. 



(a) The Tr, cerebello-spinales. These tracts are much better known 

 than are the sensory fasciculi of the median portion. There are now three 

 of the tracts known: — 



1. One of these is, on good grounds, looked uiDon as the secondary con- 

 tinuation of posterior root-fibers: ihe Tr. cei-ebello-spinalis dorsalis, or the 

 lateral cerebellar tract from the vesicular column of Clarke. This fascicle 

 constitutes the major portion of the spinal connection and, curving mesially, 

 inclosing the corpus dentatiun, passes to the cortex of tlie superior vermiform 

 process. 



2. The Tr. cereiello-spiiiaJis rentrali.^, or the bundle of Gowers, whose 

 triangular cross-section may be seen in all the sections shown in Kg. 211, 

 though its entrance into the cerebelhmi is not shown in the figure. It passes 

 into the pontal tegmentum far forward, and, in the region of exit of the 

 Troclilearis, turns dorsally, embracing, within the Velum anticum, the an- 

 terior peduncle which lea-\-es the cerebellum at this point, and then turns 

 backward into the cerebellum (Auerbach, Mott). 



3. Only recently has it been demonstrated by ilonakow, and also by 

 Terrier and Turner, that still a third spinal connection exists. There are 

 thick fibers from a large nucleus of multipolar cells, which lies just where 

 the posterior peduncle enters the cerebellum. The nucleus is called, from 

 its discoverer, Deiicr's nucleus. If it is destroyed, the descending fibers 

 which arise from it degenerate as far down as the region of the lateral 

 tracts (shown in Fig. 211). 



(b) The Tr. cerebello-olivares represent another constituent of the cor- 

 pus restiforme. Their fibers become, in later stages of development, medul- 

 lated like the other fibers of the posterior peduncle. They degenerate com- 

 pletely when the hemispheres are removed. The whole bundle passes from 

 the cerebellum to the oblongata, enters this, and passes transversely across it, 

 dividing into numerous diverging fascicles, finally finding a terminus in the 

 opposite olira inferior (see Fig. 211). 



The neuroglia of the cerebellum next to the ventricle — as usual, in the boundary 

 of the central cavities — forms a thick net-work. In the white substance it is devel- 

 oped at least as strongly as in the medullary substance generally; but in the zona 



