NERVE-CELLS IN THE MAMMALIAN SPINAL-CORD. 
43 
Altogether, it appears to me most probable that the cells are to be considered 
outstanding members of Clarke’s group ; and it appears to me that they suggest a 
connection between the cells of Clarke’s column and certain other cells of the dorsal 
born. Schwalbe* creates a class, which he terms “ the solitary cells of the posteidor 
horn,” to include all the cells in the grey matter of the doi’sal cornu, after deduction 
from it of the substantia gelatinosa and the vesicular column of Clarke, He groups, 
therefore, under one title, cells differing greatly from one another in appearance, and 
of relationships probably widely different. He, further, in his explanatory figure,t 
indicates as the chief of these “ solitary cells of the posterior horn ” the compara¬ 
tively closely-arranged smallish cells at the base of the processus reticularis, which 
Clarke described as part of his tractus intermedio lateralis. These cells are cer¬ 
tainly anything rather than “ solitary ” in their distribution [cf. fig. 4, Plate 3), 
and it seems to me that Clarke was justified in not considering them within the 
confines of the dorsal cornu at all. But among ganglion-cells, situated undoubtedly 
within the dorsal cornu, are certain that might more fittingly be termed “ solitary ” 
cells, and seem to form a division apart. These resemble strikingly, in some features, 
the out-lying cells of the radicular zone. If in sections of, for instance, the lower 
lumbar cord, the fibre-bundles of the dorsal roots be examined where they plunge at 
intervals through the median limb of the gelatinosa, certain sparse ganglion-cells can 
be found (figs, 16, 17, 18, 19.) Large and spindle-shaped, they occur in the sections 
for the most part singly ; but also, though rarely, two or even three together. The 
recrion of the dorsal horn that extends between the substantia gelatinosa and the 
longitudinally running bundles of the dorsal root, is very scantily occupied by ganglion- 
cells. It is in this region, and especially in that part of it adjoining the gelatinosa, 
that the large ganglion-cells chiefly appear. The longer axis of the cell is, in most 
instances, set parallel with the lines taken by the bundles of root-fibres that pierce 
the gelatinosa horizontally. The shape of the cell is that of a broad spindle, tapering 
to processes at the ends. The constancy with which these cells are seen, lying near 
or upon the root-bundles, and their direction with the bundles, makes a connection 
between the cells and fibres of the bundles highly probable. If one of these cells, 
with the adjacent root bundle, were situated in the wdute matter of the extero- 
posterior column, I doubt whether it would be possible to discriminate between it 
and the out-lying cells, described in this paper as so resembling the cells of Clarke’s 
column. May not these cells, therefore, be equivalent to the cells of Clarke’s 
column ? The more so, that in many cases they lie barely more within the grey 
substance than do the out-lying cells of the radicular zone, for they are seen on the 
mesial aspect of the gelatinosa, between it and the white matter of the posterior 
column. There, also, they lie near to and parallel with certain of the bundles of the 
* ‘ LelirbucL d. Neurologie,’ p. 350. 
t Letter e in fig. 221, p. 347. 
G 2 
