X 



THE FOEE-BEAIN 



always correspond with those visible to the naked eye. Usually 

 tin-re may be distinguished (Meynert and Eamoii y Cajal) : 

 (a) a superficial molecular layer ; (&) one or two layers of large 

 and small pyramidal cells ; (c) one or two layers of polymorphic 

 and spindle-shaped cells. A marked difference is to be seen in 

 the various regions of the cortex in the form and size of the 



FIG. 266. Gyri at the base of the brain. Diagrammatic. The chiasma is turned backwards. 



nerve-cells, and in the depth and delimitation of the different layers. 

 In the central convolutions, adjacent to the sulcus of Rolando, 

 some of the deeper pyramidal cells assume comparatively gigantic 

 proportions, as first noted by Betz and Bevan Lewis, but this is 

 not observed in the cortex of the occipital, temporal, or frontal 

 lobes, in which the place of the giant cells is largely occupied 

 by the smaller pyramidal cells and by small angular cells. 



To Brodmaun belongs the credit of having recently (1909) 



