260 THE RHOMBENCEPHALON. 



Fibers of the Granular Layer (Figs. 82 and 83). The nerve 

 fibers of the granular layer are as follows: (a) The processes of 

 the granules, (b) the axones of Purkinje's cells running down into 

 the medullary projection, together with their recurrent collaterals, 

 and (c) corticipetal fibers, most of which run through the granu- 

 lar layer, without branching, to end in the first layer; the remainder 

 terminate in the deep layer in the moss-like appendages of Cajal. 



The functions of the stellate cells, the "basket cells" and the 

 granule cells are probably receptive and associative; they receive 

 impulses through the projection fibers and transfer those impul- 

 ses to the dendrites or bodies of Purkinje's cells. Purkinje's 

 cells originate impulses for the coordination of muscular action 

 (Gordinier), and for the inhibition of nervous activity in the op- 

 posite cerebral hemisphere (Russel). Lesions in the cerebellum 

 produce incoordination, chorea, athetosis and, rarely, convulsions. 



The neuroglia of the cerebellum is similar to that in the cere- 

 brum. The short-rayed cells are scattered throughout the gray 

 substance, while the long-rayed are located near, or within, the 

 white substance. In the region of Purkinje's cells, near the sur- 

 face of the deep layer, are the bodies of the arborescent cells, whose 

 processes form a fine interlacement about the cell-bodies of Pur- 

 kinje and then extend in parallel lines out to the surface. They 

 form a neuroglia felt-work just beneath the pia mater (lamina 

 basalis). 



II. GANGLIONAR GRAY MATTER. 



The ganglia of the cerebellum are the nucleus dentatus, nucleus 

 emboliformis, nucleus globosus and nucleus fastigii (Figs. 81 

 and 84). All these nuclei are made up of stellate cell-bodies, 

 which vary in size from six to forty microns. They form relay 

 stations in the paths going out of the cerebellum. In them termin- 

 ate axones of Purkinje's cells. 



The nucleus dentatus (corpus dentatum) is a wavy, sinuous 

 pouch of yellowish-brown gray matter imbedded in the medul- 

 lary body of each hemisphere. The nucleus dentatus measures 

 a half inch in length and a quarter of an inch in width (Fig. 81). 



