CORTICAL CELL L \MIXATIOX OF PAPIO HAMADRYAS. G27 



In Type 10 the gi-anule layer is present but poorly deve- 

 loped. Types 10 and 11 agree in a point which Brodmann 

 regards as important, namely, that owing to the tangential 

 arrangement of the fibres in the lower part of the cortex the 

 cells of the innermost layer tend to lie in tangential rows 

 and not in radiating rows more or less vertical to the 

 surface. 



The Frontal and Prefrontal Types (figs. 3 and 4). 



o o o o o o 



o o O O O o 



The drawing of the frontal cortex (fig. '3) is taken from the 

 lateral surface of the hemisphere on the upper side of the 

 sulcus i-ectus, about two thirds of its length from its posterior 

 end. Here the depth of the coi^tex is approximately 2 mm. 

 The lamina zonalis (i) occupies the upper "2 mm. of this. 

 The lamina granularis externa (ii) extends to a depth of 

 rather over ••3 mm., Avhile the lamina pyramidalis (iii) forms a 

 zone of which the lower border lies '9 mm. from the surface. 



There is nothing remarkable about any of these layers; as 

 is usually the case the pyramids of layer iii increases in size 

 from above downwards, but the large cells near the lower 

 border do not form at all a well-marked layer. The lamina 

 granularis interna (iv) extends from a depth of '9 to a depth 

 of 1*2 mm. or lower, but it is overlapped by the lamina 

 ganglionaris (v), the large cells of which spread upwards 

 among the granules and downward to a deyjth of about 

 1*4 mm. The rest of the cortex is occupied by the lamina 

 multiformis (vi), which fades away into the white matter. 

 The cells of this layer are more concentrated near its upper 

 border, thus forming a distinct band between which and (v) 

 is a slightly clearer stratum. This type of cortex corresponds 

 exactly with Brodmann's type 9 or Campbell's " frontal." 



The prefrontal type is illustrated in fig. 4 — a drawing of a 

 strip of cortex taken from the gyrus rectus about half-way 

 alono; it. 



