338 



PLATE XXIV. 



FIGURE 1. 



Type of cell-lamination in the frontal area. From a section passing through the middle of 

 the second frontal gyrus. It will be interesting to compare this with Plate XXI., tigure 2, and 

 notice that in the layer of medium-sized pyramidal cells (3) there is a marked numerical increase 

 of elements; the same remark applies to the external layer of large pyramidal cells (4). But 

 it must be specially observed that the cells of the latter layer have suffered a pronounced 

 reduction in size. The layer of stellate cells (5) holds far greater prominence than it did in 

 the intermediate precentral cortex. Another differential point, almost of greater importance, is the 

 weak development of the internal layer of large pyramidal cells (6) in this area. 



Low power drawing, x - ; high power, x if-&. 



FIGURE 2. 



Type of cell-lamination in the prefrontal area. Section from the outer surface of the hemi- 

 sphere at the extreme anterior end. (Frontal pole.) 



On comparing this with figure 1, it will be noticed that while there is no obvious difference 

 in the first, second and third layers, the large external pyramidal cells (-1) are markedly altered, 

 having undergone a pronounced reduction in size as well as in number. The stellate lamina (4) 

 is as distinct as it was before. At 6 (internal layer of large pyramidal cells) elements deserving 

 of the distinguishing term " large " are non-existent. Still a few cells are seen similar in shape 

 and almost equal in size to those at 4, and these are certainly larger than surrounding bodies. 

 The weak development of layer 6 probably accounts for the apparent increase in depth of the 

 layer of fusiform cells. 



Of all the areas, this is the most poorly represented as regards both nerve cells and nerve 

 fibres. 



Low power drawing, x ~; high power, x i|i. 



