THE BRAIN. 



503 



into the posterior part is followed by paralysis of sensation, 

 because in this part of the capsule are the fibers which carry 

 the sensory impulses from the cord to the cortex. The cerebral 

 ganglia are subordinate centers : the corpus striatum with regard 

 to motion ; the optic thalamus with regard to sensation, particu- 

 larly to vision. 



Microscopic Structure of the Cerebrum (Figs. 293, 294). The 



FIG. 293. The layers of the 

 cortical gray matter of the cere- 

 brum (Meynert). 



llitl 



mmw 





. d 



FIG. 294. Schematic diagram of the cerebral 

 cortex: a, molecular layer with superficial 

 (tangential) fibers ; &, striation of Bechtereff- 

 Kaes ; c, layer of small pyramidal cells ; d, 

 stripe of Baillarger ; e, radial bundles of the 

 medullary substance ; /, layer of polymor- 

 phous cells (Bohm and Davidoff). 



Gray Matter. The gray matter on the external surface of the cere- 

 brum, the cortex, is divisible into five layers, whose distinctness 

 varies in different regions, being perhaps most marked in the 

 parietal lobe ; but in the posterior portion of the occipital lobe, 

 in the gray portion of the hippocampus major, in the wall of 



