708 
MR. W. BE VAN LEWIS ON THE COMPARATIVE 
although, they do not approach the dimensions of the same elements in the Pig. Thus 
in the upper limbic arc of the Pig the larger cells averaged 48/xX 17/x, the largest in 
the Babbit, being 32/xX 18/x, measurements suggestive not only of the greater size of 
these cells in the Pig, but of their far more elongate contour. The typically elongate 
cell however occurred in the Sheep, as exhibited by their measurements of 46p,X lip,. 
The above considerations lead us to conclude that whilst these cells undoubtedly 
represent the ganglionic series of Man and the higher Mammalia, yet in size, contour, 
and structural type these cells in the Babbit lose the strong distinctive features which 
characterise the ganglion cells of Man, whilst on the other hand they acquire structural 
affinities to the larger pyramids in the human cortex approximating as closely to them 
as was the case in the Sheep and Pig; in short, the structural type of the ganglionic 
cell is modified, being less complex. 
Regional distribution (Plate 49, fig. 3).—In describing the cortex of the Pig 
and Sheep it was shown that this ganglionic layer assumed the form of a nested 
or clustered and a laminar or linear arrangement of its cells, but that in the 
former case the clusters were either far apart or discrete, or tended to become 
confluent. In the Babbit the true nested arrangement is not to be found, as the 
clusters all tend to become confluent. The characteristic formation therefore over 
the upper limbic arc is that of a deep and dense layer, the cells uniformly dis¬ 
tributed throughout, and in this plan again they more closely resemble the large 
pyramidal cells of Man than the subjacent layer. In the portion of the upper limbic 
arc which bends down in front of the corpus callosum (Plate 49, fig. 3, A and B), there 
is a most notable development of this layer. The ganglionic belt is here deep, and 
consists of large cells densely congregated and commencing abruptly beneath the small 
pyramidal layer. Its depth and richness in cells increases upwards towards the exposed 
aspect of the hemisphere, the quarter-inch field usually showing 60 to 80 cells, so that 
the margin of the longitudinal fissure here has a most exceptionally rich development 
of this layer. This rich formation is continued outwards over the whole of the areas 
numbered 7 and 9 by Fekrier,* and terminates only at the limbic fissure. As in the 
corresponding series in higher animals, the deepest portion of this layer is pale, having 
very few small cells, although at wide intervals apart are found some of the largest 
size ganglionic cells. Again referring to the diagram, we find from C to D the 
decreasing depth of the layer shows a corresponding diminution hi the richness of its 
cells, which, however, are still numerous as far as D, and increase in number toward 
the outer or exposed aspect of the hemisphere. Beyond the sagittal margin, however, 
we find that from being closely congregated, the poorest development of cells yet met 
with occurs, as they rapidly thin out into an almost linear series down the outer aspect 
of the hemisphere as far as the great limbic fissure. Betwixt them and the small 
pyramidal layer I met with a belt of small angular cells, so that the cortex becomes 
five-laminated. Beyond D, the layer becomes rapidly shallower and the cells distant 
* “Functions of the Brain,” fig. 36, 
