CEREBELLUM 175 



the organ are several masses of grey matter on each side, the 

 most important of which are 1, the roof nucleus ; and 2, the 

 dentate nucleus (fig. 87, R.N. and Dent. ). 



The eoptex may be divided into an outer somewhat homo- 

 geneous layer (the molecular layer, fig. 88, G.L.) and an inner 

 layer studded with cells (the nuclear layer, N.L.). Between 

 these is a layer of large cells the cells of Pur kin je (P.). 



By Golgi's method the arrangement of fibres and cells in 

 the cerebellar cortex has been shown to be as follows : 



Fibres coming into the cortex from the white matter end 

 either in synapses round cells in the nuclear layer, or proceed 

 at once to the outer layer (fig. 88). From the cells in the 

 nuclear layer, processes pass to the outer layer and there form 

 synapses with other cells. From these, processes pass to the cells 

 of Purkinje, round which they arborise, and from Purkinje's cells 

 the outgoing fibres of the cerebellum pass into the white matter, 

 and so to the deeper ganglia, and to Deiters' nuclei (fig. 87). 



Connections 



The cerebellum is connected (fig. 89) : 

 i. With the Spinal Cord. 



a. Incoming Fibres. 1. The direct cerebellar tract (p. 172) 

 passes up in the restiform body to end chiefly in the superior 

 vermis. 2. The ascending ventro-lateral tract (p. 174) passes 

 to the cerebellum in the superior peduncle and ends in 

 the superior vermis. 3. Fibres from the nuclei of the dorsal 

 columns of the same side (fig. 84, p. 177) pass in the restiform 

 body to the cerebellum. 4. Fibres from the vestibular root 

 of the eighth nerve also pass to the cerebellum (fig. 81, p. 152). 



b. Commissural Fibres. Strong bands of fibres connect the 

 inferior olive of one side with the dentate nucleus of the other. 



c. Outgoing Fibres. Fibres pass from the superior vermis 

 to the deep nuclei, and, from these, fibres run to Deiters' nuclei 

 (fig. 87), from which fibres pass down in the descending ventro- 

 lateral tract of the cord. 



ii. With the Cerebrum. 1. The fibres of the middle 

 peduncles cross in the middle line embracing the medulla, 

 and forming the pons Varolii, and become associated with cells 

 from which fibres pass up in the lateral parts of the crura 

 cerebri to the cerebral cortex (fig. 90, CC. CC., p. 187). 



