CH. XLV.] 



THE CEREBELLUM. 



641 



layer of grey matter is made up of a large number of small nerve- 

 cells mixed with a few larger ones, and some neuroglia-cells. 

 Between the two layers is an incomplete stratum of large flask- 

 shaped cells, called the cells of Purkinje. Each of these gives 

 off from -its base a fine process which becomes the axis-cylinder 

 of one of the medullated fibres of the white matter ; the neck of 

 the flask passing in the opposite direction breaks up into dendrites 

 which pass into the external layer of grey matter. By Golgi's 

 method (fig. 475) these dendrons have been shown to spread out 

 in planes transverse to the direction of the lamellae of the organ. 



I. II. 



Fig- 475. Section of cerebellar cortex, stained by Golgi's method; i. taken across the 

 lamina; n. in the direction of the lamina: A, outer or molecular layer; B, inner or 

 granular layer ; c, white matter, a, Cell of Purkinje ; b, small cells of inner layer ; <. 

 dendrpns of these cells ; </, axis-cylinder process of one of these cells becoming longitu- 

 dinal in the outer layer ; e, bifurcation of one of these ; g, a similar cell lying in the 

 white matter. (Ramon y Cajal.) 



Each cell of Purkinje is further invested by arborisations of 

 two sets of nerve-fibres. One of these (originating from the fibres 

 of the white matter which are not continuous as axis-cylinders 

 from the cells of Purkinje) forms a basket-work round the 

 dendrons ; the other (originating as axis-cylinder processes from 

 the nerve-cells of the external layer) forms a felt-work of fibrils 

 round the body of the cell. 



The cells of the intemal layer of grey matter are small ; their 

 dendrites intermingle with those of neighbouring cells ; their axons 

 penetrate into the external layer, but their final destination is 

 uncertain. Ramifying among these cells are fibres characterised 

 by possessing bunches of short branches at intervals (moss-fibres 

 of Cajal). 



K.P. 



T T 



