CHAP. X.J 



THE CEREBELLUM. 



271 





Analytical diagram of the encephalon in a vertical section. (After Mayo.) 



.v. Spinal cord. >: l;r<tiiorm bodies passing to, c, the cerebellum, d. Corpus dentatum of the 

 ffivU'lluni. o. Olivary body. /. Columns continuous with the olivary bodies and central part of 

 thr medulla oblongata, *nd ascending to the tubercular quadrigemina and optic thalami. p. An- 

 terior pyramids, v. Fons Varolii. ra, ft. Tubercula quadrigemina. g. Geniculate body of the optic 

 thalanuis. t. Trocessus cerebelli ad testes. . Anterior lobe of the brain, q. Posterior lobe of the 

 brain. 



demonstrated by making a vertical section through the cerebellar 

 hemisphere, leaving two-thirds of its substance to the outside of the 

 section. The surface of the section presents at the situation above 

 described a remarkable layer or capsule of gray matter, surrounding 

 in great part an oval space ; the gray layer has an undulating dis- 

 position, and is convex towards the surface ; but open towards the 

 crus. The precise object of this remarkable structure is not known ; 

 but the microscopic investigation of it shews that in it there is a 

 mingling of the elements of the vesicular and fibrous substances. 



The central stem, or crus, around which each hemisphere of the 

 cerebellum is developed, is formed by three bundles of fibres, each 



