THE BRAIN. 403 



layer and connect with the dendrites of Purkinje 

 cells, up which they seem to climb. Collaterals are 

 given off in their passage through the granular layer. 

 The central gray nucleus forms the central core of 

 each lateral cerebellar hemisphere. It forms a cap- 

 sule of gray matter from whose hilum many nerve 

 fibers pass, the majority to enter the superior cerebel- 

 lar peduncle. 



THE CEREBRAL CORTEX. 



The cerebrum is such an extensive and complicated 

 organ that only a description of the cortex in the 

 region of the fissure of Rolando will be given here. 

 From without inward this region presents, rather 

 indistinctly, the following layers: (T) molecular 

 layer; (2) small pyramidal cells; (3) large pyr- 

 amidal cells; (4) polymorphic cells; (5) medullary 

 substance of nerve fibers. ' It is to be borne in mind 

 that this cortex presents many fissures and minor 

 folds into which the pia dips, and that a transverse 

 section is any plane that is vertical to the folded 

 surface. 



i., The molecular or outer layer is composed chiefly 

 of nerve fibers which interlace in all directions but 

 which have chiefly a direction parallel to the external 

 surface. The chief dendrite of the pyramidal cells 

 terminates in this layer in tuft-like telodendria, and 

 also ascending neuraxes, mostly from the polymor- 

 phous cells. The cells of this layer are few, and have 

 been described as polygonal, spindle-shaped, and 

 triangular, or stellate. Their neurons are nearly all 

 confined to this layer, the axones of only a few reach 

 down to the deeper layers. 



