53 
STRUCTURE OF THE CORTEX CEREBRI. 
ganglionic cells. Through this layer course upwards the apex processes of its cells as 
also those of the great ganglionic series below. 
Ganglionic layer .—The cells of this formation are plump, oval, or pyriform bodies, 
differing notably from the elongated pyramidal cells of the Sheep and the Pig. 
Occasionally a fusiform cell occurs, and more frequently a well-formed pyramid. They 
attain the dimensions of 51/x X 23/x, with a large oval nucleus, measuring 18 y. The 
nests are usually large and uniform, and most frequently contain from three to four 
cells (as seen in vertical sections). One of the larger and richer nests measured 
•340 mm. in depth by ‘093 mm. in breadth, and showed nine cells. The ganglionic 
cells are decidedly largest in the gyri bounding the crucial sulcus. In a former 
investigation into the structure of the gyri in this neighbourhood the following facts 
were elicited. The limbic boundary of this sulcus possessed ganglionic cells averaging 
39/x X17/x, whilst the parietal boundary of the sulcus contained cells averaging 
46g X 17/x, a large number even measuring 69pX27/x. At the external limit of the 
crucial sulcus, where the parietal gyrus bends round and unites with the limbic lobe, 
the largest cells were found (83/x X 3 7/x), whilst an occasional gigantic cell occurred, 
attaining the dimensions of 106/xX 32/x. 
The spindle layer calls for no special description here. 
Parietal lobe .—On the parietal side of the fissure of Rolando we come upon a six- 
laminated type of cortex; and just as we shall find that the crucial sulcus presents us 
with a different type of structure on its limbic and parietal walls, so here the fissure of 
Rolando separates two typical stratifications of the cortex. In short, the structure of 
the ascending frontal differs materially from that of the ascending parietal. The 
difference consists essentially in the reappearance of a distinct layer of angular cells 
below the large pyramidal series, in the larger dimensions of its ganglionic cells, and 
the fairly rich and well-formed nests of these elements. We find the average depth of 
the first cortical layer has decreased to '232 mm., and that of the next two subjacent 
layers to 'G97 mm. The cells of the ganglionic series attain an average of 37 /x X 19/x, 
with a nucleus 13/x in diameter. Passing from the ascending parietal gyrus to the 
four tiers of parietal gyri, we find the laminar conformation and structural peculiarities 
of this great extra limbic mass to be as follows. The first and second parietal convo¬ 
lutions exhibit various stages of transition betwixt a five- and a six-laminated conforma¬ 
tion. The small pyramidal and angular layer above the ganglionic series is but poorly 
represented, and in the anterior extremities of these convolutions the cells are so few 
and so thinly scattered that the formation scarcely deserves the name of a distinct layer, 
whilst in the posterior extremities of the same gyri the layer is more richly developed, 
The arrangement of the ganglionic cells varies at different sites, but the nested is that 
which predominates in the first or Sylvian convolution, especially in the immediate 
neighbourhood of the Sylvian fissure. Towards the inter-parietal sulcus these clusters 
become more distant, and constituted of fewer cells, until a purely laminar arrangement 
* Vide ‘ Brain part 1, April, 1878. 
