STRUCTURE OF THE CORTEX CEREBRI. 
59 
Ape, the Cat, and the Ocelot than in the corresponding series in the Sheep and Pig. 
This increase in size is chiefly assumed in their short diameter or width, the cell 
being swollen, ovoid, and often approaching a globular contour. The protoplasmic 
mass forming these cells is therefore much greater in these higher animals. The 
important consideration attached to this form is dependent upon the fact that the 
swollen form is invariably associated with a far more complex branching from all parts 
of the periphery of the cell, whilst in the pyramidal cell the lateral angles give rise to 
the greater number of processes. In fact, the oval swollen cell shows numerous 
angular projections spread over its surface, from which delicate processes arise, and it 
is presumably the situation and number of these branches which form the chief 
elements in moulding the contour of the cell. Thus, the simplest cell is elongated, 
spindle-shaped, and bi-polar; the acquirement of a third process thrown off the centre 
of the body of the cell gives the spindle an angularity frequently observed in the last 
layer of the cortex. This appears to be the origin of the pyramidal form of cell and 
its various modifications and multipolar varieties. Two elementary forms of cell con¬ 
stantly occur in the cortex cerebri, which develop the one into the small pyramidal 
and angular, and the other into the large pyramidal and ganglionic series. It appears 
that wdien the processes arising from the larger cells are most numerous, we get the 
plump ganglionic cell—when less numerous, the large pyramidal cells of the third 
layer; whilst, if the complexity in branching of the smaller cell is great, we have an 
ovoid, irregular angular cell, or if few branches arise, we obtain the small pyramidal 
cell. I have stated elsewhere”' that the absolute number of branches of these cells 
could never be determined with any degree of certainty; yet it is important to bear 
in mind the fact that the irregular contour of the large swollen ganglionic cell depends 
upon multiplicity of cell branchings, and that therefore this contour in the normal cell 
may be regarded generally as indicative of greater complexity. We therefore infer 
what we may approximately ascertain by examination of vertical and horizontal sec¬ 
tions—that the cell groups of the ganglionic series have far more branches than those 
of the third layer. In Man, the Ape, Cat, and Ocelot we found the elements of the 
ganglionic series possessed this swollen contour, whilst in the Sheep and Pig they were 
almost universally elongated pyramids. The first glance at these cells in the latter 
animals suffices to establish their peculiar resemblance to the large pyramids of the 
third layer in higher animals. We therefore may with justice assume that— 
1st. The large ganglionic cells of the Pig and Sheep are far less complex in their 
relationships and connexions than the corresponding cells in the Cat, Ocelot, Ape, 
and Man. 
2nd. The same cells in the Pig and Sheep resemble closely in their general confer 
mation and complexity the large pyramids of the third layer in higher animals. 
* Loc. cit. 
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