202 Type of Cell Lamination [CHAP. 



power, it can be shown that the passage from " intermediate postcentral " to " parietal " 

 cortex is attended by an appreciable reduction in size of the contained cells. It likewise 

 appears that the larger elements, those especially rich in chromopbilic particles, diminish in 

 number. 



The distinction between the cells of this layer and those in the " general temporal " 

 area is also not easily made out ; still, after many observations I am satisfied, as regards 

 the latter area, that while the cells may possibly have an advantage in point of number, 

 they are distinctly smaller in size. Moreover, cells of the larger order, evenly supplied with 

 Nissl bodies, although by no means frequent in the " parietal " cortex, are virtually 

 non-existent in the " common temporal " region, and this, in my opinion, is a very important 

 point of difference. 



The appearance of the peculiar, large external pyramidal cells, described in the " visuo- 

 psychic " cortex, proclaims the occipital boundary as clearly as the sudden diminution in 

 size of homonymous elements marks the " limbic " cortex. 



Layer of Stellate Cells. 



In common with that of the postcentral, temporal, and occipital regions the " parietal " 

 cortex possesses a well-developed and prominent stellate layer; this, therefore, cannot be used 

 as a means to topographic differentiation. 



Internal Layer of Large Pyramidal Cells. 



Although this lamina is quite easily defined, its cells are neither so large nor so 

 numerous as those in the external layer (4). A comparison of the lamina with that of 

 surrounding regions is not instructive ; for while it differs from the " occipital " and " limbic " 

 formations, it has points in common with the "intermediate postcentral" and "temporal," 

 and in regard to relative size and number of contained cells it can only be said that the 

 statement concerning the external layer (4) holds here also 1 . 



Layer of Fusiform Cells. 



The layer of fusiform cells is a deep one ; and since the cells in the upper part are 

 larger and more triangular than those in the lower, it might be divided into two, but 

 seeing that the same arrangement is found in the temporal and parietal regions, and also 

 that the appearances do not assist us in furthering our territorial subdivision, it is preferable 

 in the mean time not to invest them with importance. 



In total depth, the " parietal " cortex does not differ from that of the " temporal " and 



" postcentral " areas. 



i 



Topica I Va riatio n s. 



There are no local variations of importance to be described. It need only be said that 

 the type of fibre arrangement and cell lamination is seen at its best in the middle of the 

 superior parietal gyrus, that is in the centre of the area, for towards the periphery it 

 takes on the appearances of the various types of cortex which surround it. 



1 As previously mentioned this layer is placed on a level with the inner line of Baillarger and there can be 

 little doubt that the two are interdependent. 



