MEDULLA OBLONGATA. 629 



readiness of transit is much less along the thin-fibred network than 

 via the direct medullated routes, the complexity of paths and the 

 variety of directions in which they lead, is much greater in the 

 gray than the white substance. It is by means of the gray sub- 

 stance that the two lateral parts of the medulla are so nearly 



FIG. 243. 



Diagram of Brain and Medulla Oblongata. (Cleland.) a, Spinal cord; 6, b, Cerebel- 

 lum divided, and above it the valve of Vieussens partially divided; c, Corpora quadri- 

 gemina; d, d, Optic thalami; , pineal body; /, /, Corpora striata; g, g, Cerebral hemi- 

 spheres in section ; h, Corpus callosum ; i, Fornix ; I, I, Lateral ventricles ; 3, Third ven. 

 tricle; 4, Fourth ventricle; 5, Fifth ventricle, bounded on each side by septum lucidum. 



related to one another, and the local centres are kept in commu- 

 nication with the distant parts. 



The posterior gray columns of the spinal cord are partly con- 

 tinued on by fine strands into the cerebellum by its peduncles, 

 and partly are carried on to the brain through the cerebral 



