274 Microscopic Structure of Cortical Areas 
transitional types. The cortex of each sensory area is evidently composed 
of two differently constructed sets of layers: 
1. The layers of specific elements (the spindle cells of the gyrus forni- 
eatus, the granule cells of the visual sphere, the giant cells of the central 
gyri, the cylindrical cells of the auditory area, etc.); and 
2. The elements of the association centers which spread over the entire 
cortex, 
The association centers contain in their cortex elements only of the 
latter kind, but these layers also pass into sensory centers, so that the latter 
frequently present slight resemblances of the structure of the association 
centers. 
1 cannot agree to everything Flechsig says here. That in some places, 
as, for instance, in the motor area, giant cells and in the cornu ammonis 
characteristic cells are found, is, no doubt, plainly evident. But I can- 
not agree with him when he says, that in the visual area only, granule 
cells are found, or that in the auditory region only cylindrical cells are 
feund, or that only in the anterior portion of the gyrus fornicatus are 
found the large characteristic spindle cells. The granule cells which 
he finds only in the visual region, are found almost everywhere in the 
cerebral cortex, not in equal numbers, however, as I have already pointed 
out. The cylindrical cells, which he claims to have found only in the 
auditory area, I have not been able to find in that part of the temporal 
lobe, of which I have obtained good specimens, and some ‘of the sections 
have surely been made through the auditory area. 
The main distinction between the different cortical regions does not 
appear so much in the individual cells as it does in the composition of 
the entire cortex. It is true that the large giant pyramidal cells are 
very characteristic of the motor area, and in the visual area those cells, 
which may be considered analogous to the pyramidal cells in the adjoin- 
ing areas, are no more so distinctly pyramidal in shape. These modifi- 
eatiuns can probably be brought into accord with the following facts: 1 
have already pointed out that in the visual area the cells are no more 
arranged in rows perpendicularly to the upper surface of the cortex, and 
that the fiber striations are no longer so conspicuous. We may conclude 
from this, that the radiating fibers are not developed so well in the direc- 
tion of the outer layer of tangential fibers as in the stripes of Baillarger. 
Tn consequence, these two inner layers of tangential fibers, or stripes of 
Baillarger, are enormously developed. (The fifth and seventh layers of 
the eighth layer type.) This is followed by, or is the result of, the fact 
that the cells do not send one large dendrite to the periphery, giving 
them a pyramidal shape, but send many dendrites to the inner layers of 
the tangential fibers, for which reason they become more polymorphous. 
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