88 



THE CEREBELLUM. 



The molecular layer is further in large part occupied by the dendritic proto- 

 plasmic processes of the large nerve-cells which lie at the junction of the granule 

 and medullary layers, already mentioned as the cells or corpuscles of PurTcinje. These 

 are conspicuous flask-shaped cells, each with a number of ramified protoplasmic pro- 

 cesses directed peripherally, and an axis-cylinder or nerve-process which passes 

 centrally into the granule-layer, where it becomes medullated, and passes directly 

 into a nerve-fibre of the medullary centre. As with the axis-cylinder processes of 



Fig. 64. SECTIONS OF CORTEX CEREBELLI STAINED BY GOLGI'S METHOD. (Kam6n y Cajal.) 



I. Section taken across the lamina. 



II. Section made in the direction of the lamina. 



A, outer or molecular layer ; B, inner or granule layer ; C, medullary centre. 



a, corpuscle of Purkinje ; b, small granules of inner layer ; c, a protoplasmic process of a granule ; 

 d, nerve-fibre process of a granule passing into the molecular layer, where it bifurcates and becomes a 

 longitudinal fibre (in I. these longitudinal fibres are cut across and appear as dots) ; e, bifurcation of 

 another fibre ; g, a granule lying in the white centre. 



the cells of the cerebral cortex, and, according to Golgi, with those of the anterior 

 horn-cells of the spinal cord, these axis-cylinder processes of Purkinje's cells also 

 give off lateral ramuscles (collaterals) which lose themselves amongst the granules, 

 some turning backwards to enter the molecular layer (figs. 69, 70). The protoplasmic 

 processes of the cells of Purkinje are spread out in planes which run transversely to 

 the laminae (Stilling), so that they are seen in their full extent only in sections 

 cut vertically to the surface but across the laminae (fig. 64, I.) ; whereas in vertical 

 sections taken parallel to the laminae, the ramifications appear limited to a com- 

 paratively narrowed tract (fig. 64, II.). The protoplasmic processes (dendrites) may 

 arise by a single root or by two roots ; in either case there is a frequent dichotomous 

 division, with slight enlargements at the points of division, and also the giving off 

 laterally of numerous ramuscles which take a more horizontal course in the mole- 

 cular layer than do the principal branches. The branches do not anastomose nor 



