THE CENTRAL NERVOUS SYSTEM. 



305 



the white matter of the medulla, together with certain additional gray 

 nuclei embedded within the latter. On section, each leaflet of the 

 cerebellum is seen to be made up of (i) a central core of white 

 medullary substance, which blends into (2) the granule layer, 

 characterized by its "rust-color," external to which follows (3) the 



FIG. 337. 



2- 



Section of human cerebellum, slightly magnified to show general arrangement : w, white matter of 

 medulla ; g, o, granule and molecular or outer layer, between which lies layer of Purkinje's cells (/>). 



outer or molecular stratum ; between the latter and the granule 

 layer lies (4) the single row of ganglion-cells which constitutes the 

 layer of the cells of Purkinje. 



The granule layer forms a zone conspicuous on account of the 

 great number of small deeply-staining cells which it contains. It 

 varies in thickness, being broadest at the summit of the laminae 

 and narrowest at the bottom of the fissures. Towards the outer 

 layer the zone is sharply defined, but it fades away on the median 

 side into the medullary substance. 



The nerve-cells of the granule layer are of two kinds, the 

 small and the large ganglion-cells. The former are small (6-7 p) 

 round elements, stain deeply, but possess so little protoplasm that 

 the greater part of the cell is formed by the nucleus. These cells, 

 the principal elements of this layer, are arranged in irregular groups ; 

 they are multipolar, and have, according to recent investigations, 



