CORTICAL CELL LAMIXA'I'IOX OF PAPIO HAMADRYAS. 631 



pyramids in no wise remarkable, and a lower stratum (iiifc), 

 which is very conspicuous, and constitutes the most charac- 

 teristic featui*e of the post-central cortex, iii h extends from 

 a depth of "5 mm. to a depth of '85 mm., and its principal 

 constituents are large cells closely crowded together, and 

 lying about tliree deep. Their shape and approximate size 

 may be gathered from the drawing; they are elongated pear- 

 shaped or pyramidal cells drawn out above into a broad 

 process which takes the stain rather faintly. It is difficult 

 to give a numerical indication of their size, but this may 

 be as much as 60 or 70 /u x 30 ^. The lamina granularis 

 interna is a dense layer of granules intermixed with small 

 pyramids; its lower limit is '1 mm. below that of iii 6, but 

 above it is extended by columns of small cells which lie 

 between the large elements of that lamina. 



Closely underlying iv is the lamina gauglionaris v. This 

 consists of a number of triangular quadrilateral and other 

 elements of comparatively small size, among which are 

 scattered occasional pyramids of notably superior size; these 

 cells, which lie near the lower border of the layer, at a depth 

 of 1'2 mm., are inferior in size to the supra-granular pyramids, 

 and differ from them also in shape ; their cell-bodies ai-e 

 more slender, and their apical processes narrower and more 

 darkly staining. The rest of the cortex is occupied by the 

 lamina multiformis (vi), which is separated f rom v by a zone 

 comparatively poor in cells. It cannot be subdivided into 

 a lamina triangularis and a lamina fusiformis. 



The cortex described above corresponds to Brodmann's 

 types Nos. 1 and 2. As it dips over in front into the sulcus 

 centralis it alters somewhat in character; the whole cortex 

 becomes narrower ; the large cells at iii 6 become reduced in 

 size and number; the layer of granules (iv) grows less 

 distinct, and the lamina ganglionaris suffers the same changes 

 as iii h. 



According to Brodmann, the large cells at iii b and v, which 

 form the most characteristic feature of the post-central 

 cortex, are larger and more numerous near the posterior lip 



