THE CEREBELLUM. 



1091 



and often acute angles, the completed division resulting, as displayed by silver 

 impregnations (Fig. 944), in an arborization of astonishing richness and extent that 

 often reaches almost to the outer boundary of the molecular layer. The dendritic 

 ramification of each cell is limited, however, to a narrow zone extending across the 

 folium and, hence, when examined in sections cut parallel with the plane of the folium, 

 these expansions are found to be confined to tracts separated by zones of the molecular 

 layer that are uninvaded by the dendrites of the Purkinje cells. The axones of 

 the latter arise from the rounded basal or deeper end of the pyriform body and at 

 once enter the granular layer, which they traverse to gain the white medullary core 

 of the folium. In their course the axones give off a few recurrent collaterals that 

 end within the molecular layer in the vicinity of the bodies of the cells of Purkinje. 

 The stellate or basket cells lie at different planes, but chiefly within the 

 deeper half of the molecular layer. They possess an irregular stellate body, from 

 .OIO-.O2O mm. in diameter, from which several dendrites radiate. Their chief 

 feature of interest is the 



remarkable relation of FIG. 944 



the axone, which extends 

 across the folium in an 

 approximately horizontal 

 plane along and to the 

 outer side of the row of 

 the Purkinje cells. During 

 this course the axone gives 

 off from three to six 

 collaterals that descend 

 to the cells of Purkinje, 

 whose bodies they sur- 

 round and enclose with a 

 basket - like arborization, 

 the terminal ramification 

 of the main process itself 

 ending in like manner. 

 By means of this arrange- 

 ment each basket cell is 

 brought into close relation 

 with several of the larger 

 elements. 



Purkinje cell from silver preparation of cerebellar cortex; A, axone. X 120. 



The small cortical 

 cells occur at all depths, but are most numerous in the more superficial planes, 

 in which they appear as diminutive multipolar elements with radiating dendrites and 

 axones of uncertain destination. 



The granule layer, of a rust-brown tint when fresh and deeply colored in 

 stained preparations, is thickest on the summit of the folia and thinnest opposite the 

 bottom of the sulci. While sharply defined from the overlying molecular layer, it is 

 less clearly distinguished from the medullary substance. The granular layer con- 

 tains two varieties of nerve-cells the granule cells and the large stellate cells. 



The granule cells are very small (.ooy-.oio mm.) and numerous and so closely 

 packed that they confer upon the stratum its distinctive density. They are provided 

 with from three to six short radiating dendritic processes that end in peculiar claw- 

 like arborizations in relation with other granule cells. The axones, directed towards 

 the surface, enter the molecular layer, within which, at various levels corresponding 

 to the depth of the cells, they undergo T-like division. The two resulting branches 

 run horizontally and lengthwise and in the folium that is, parallel to the surface and 

 at right angles to the plane of expansion of the dendrites of the Purkinje cells, through 

 the arborizations of which they find their way and with which they probably come 

 into close relation. 



The large stellate cells are present in varying number, but are never 

 They lie close to the outer limit of the granule layer and possess a cell-body c 



ous. 



. 

 uncertain and irregular form, from .030-. 040 mm. in diameter, from which usually 



