594 



NERVOUS SYSTEM 



process of the dura mater, called the tentorium. Like the cerebrum, 

 the cerebellum presents an external layer of gray matter, the interior 

 being formed of white, or fibrous nerve-tissue. The extent of the gray 

 substance is much increased by convolutions and by the penetration 

 from the surface of arborescent processes of gray matter. Near the 

 centre of each lateral lobe, embedded in the white substance, is an 



Fig. 148. Section of a cerebellar lamina perpendicular to its axis (R. y Cajal). 



A, molecular layer ; B, granular layer ; C, white substance ; a, cell of Purkinje; o, its neurite with 

 two collaterals; b, b, stellate cells of the molecular layer; d, basket-like arrangement of teloneuriles 

 around a cell of Purkinje; e, superficial stellate cell; /, large stellate cell of the granular layer; g, small 

 stellate cell of the granular layer; h, centripetal neurite; n, centripetal neurite distributed in the molec- 

 ular layer; /, m, neuroglia. The arborescent dendrites of one only of the cells of Purkinje are repre- 

 sented in the figure. 



irregularly-dentated mass of gray matter, called the corpus dentatum. 

 The convolutions are finer and more abundant and the gray substance 

 is deeper in the cerebellum than in the cerebrum. These convolutions, 

 also, are present in many of the inferior animals in which the surface 

 of the cerebrum is smooth. 



The cerebellum consists of two lateral hemispheres, more largely 

 developed in man than in the inferior animals, and a median lobe. The 



