THE FUNCTIONS OF THE CEREBELLUM 



399 



where they end in a rich basket-work of fibres around the body and beginning of the 

 axon of these cells. The nuclear or granular layer presents two kinds of cells. The 

 most numerous is a small cell with a few short dendrites, each of which terminates 

 in a claw-shaped arborisation, and a single long axon, which passes straight up into 

 the molecular layer, where it bifurcates. The two branches run parallel with the 

 surface in a direction at right angles to the plane of expansion of the dendrites of 

 Purkinje's cells, apparently resting against the serrations on the edges of these processes. 

 The second kind of cell in the granular layer is the so-called Golgi's cell a large cell 





Central 



white 



matter. 



FIG. 201. Schema of constituent elements of cerebellum. (Modified from BOHM 

 and DAVIDOFF.) On the left is a section of the cortex as it appears when 

 stained by ordinary methods. The middle portion represents diagrammatically 

 a section at right angles to the laminae, while to the right of the dotted line the 

 section is taken in the same plane as the laminse. 

 a, star-shaped cells of molecular layer ; 6, b, cells of Purkinje ; c, ' Golgi cell ' ; 



d, small cells of nuclear layer ; e, ' tendril fibre ' ; /, ' mass fibre ' ; g, axon of cell 



of Purkinje. 



with many dendrites and an axon which terminates by frequent branches in the neigh- 

 bouring grey matter. 



The fibres making up the white matter are of three kinds two afferent and one 

 efferent. The moss fibres, so called from the curious thickenings they present in the 

 nuclear layer, pass up into the grey matter and terminate by frequent branches in 

 this layer. The tendril fibres, also afferent, end in a rich arborisation which surrounds 

 the distal part of the bodies and the bases of the dendrites of the cells of Purkinje. 

 The efferent fibres are represented by the axons of the cells of Purkinje, which acquire 

 a medullary sheath and run down into the white matter. 



This slight sketch of the anatomy gives us a conception of the extreme complexity 

 of choice presented to nervous impulses traversing the cerebellar cortex. Thus a 

 discharge along an axon of the cell of Purkinje may be excited (1) by an impulse ascend- 

 ing the tendril fibres ; or (2) by one ascending the moss fibres through the granule 

 cells, and then passing by their bifurcating axon to the dendrites of the cells of Pur- 

 kinje ; or (3) by the star-shaped cells of the molecular layer and their basket-work 

 round tfie body of Purkinje's cells. 



