6i8 



THE NERVOUS SYSTEM 



The General Structure of the Cerebellum. The molecular layer 

 of the cerebellum contains several peculiar types of nerve cells, of which may 

 be specially mentioned Purkinje's cells and the basket cells. The cells of 

 Purkinje lie along the internal margin of the molecular layer, being, in fact, 

 practically at the boundary of the molecular and granular layers. They 

 measure 40 to 60 /* in diameter, and have large, round nuclei. Each cell 

 gives off an enormous number pf branching dendrites, which run up toward 

 the surface of the cerebellum in the shape of a bush. 



The cells of Purkinje give off at their deeper surface an axone which 

 runs down into the white matter of the cerebellum. Recurrent collaterals 

 occur. 



FIG. 385. Outline Sketch of a Section of the Cerebellum, Showing the Corpus 

 Dentatum. The section has been carried through the left lateral part of the pons, so as to 

 divide the superior peduncle and pass nearly through the middle of the left cerebellar 

 hemisphere. The olivary body has also been divided longitudinally so as to expose in 

 section its corpus dentatum. cr, Crus cerebri;/, fillet; q, corpora quadrigemina; sp, superior 

 peduncle of the cerebellum, divided; mp, middle peduncle or lateral part of the pons Varolii, 

 with fibers passing from it into the white stem; av, continuation of the white stem radiating 

 toward the arbor vitse of the folia; o, olivary body with its corpus dentatum; p, anterior 

 pyramid. (Allen Thomson.) 



Lying in the molecular layer, somewhat external to the Purkinje cells, 

 are the cells of the type known as basket cells. These cells have a number of 

 dendrites; they also send out an axone which runs parallel to the surface of 

 the cortex and gives off numerous collaterals in its course that form baskets 

 around the cell bodies of the Purkinje cells, figure 386, ZK. 



The granular layer contains a large number of very small granule-like 

 cells that Golgi was the first to show are really nerve cells. They are only 

 about 5 // in diameter, and they have a number of short dendrites which end in 

 clubbed extremities. They give off a very slender axis-cylinder process or 

 axone which runs up into the superficial part of the molecular layer and 

 there divides in a T-shaped fashion, the fibers run parallel to the surface 

 of the convolution and pass in between the branches of the cells of Purkinje. 



The white substance of the cerebellum consists of nerve fibers, which are 



