THE LUMBAR ENLARGEMENT OF THE SPINAL CORD. 935 
figures which accompany this paper will show cells which, according to Jacubowitsch, 
should be sensitive, in the anterior cornua, and large or motor cells in the posterior 
cornua. ; 
The nerve-cell appears to be simply an enlargement of the axis cylinder, containing 
a granular substance and a nucleus. Sometimes by the use of a power of 100 — 900 
diameters I have thought that I detected a cell wall from which the coagulated cell 
contents seemed shrunken away. With the description which Stilling gives of the 
minute structure of cell and fibre I cannot at all agree, being convinced, from what 
little investigation I have been able to make, that the so-called elementary tubuli are 
produced artificially by the coagulating action of chromic acid ; and Clarke has recently 
shown that these appearances may be produced at will in fresh nerve fibre, either by 
coagulation or mechanical agency. * 
(B.) The Groups of Nerve-Cells, and their Situations. — The groups of cells situated 
in the anterior cornua have already been fully described by Clarke, Stilling, and 
various other authors. I shall confine my own observations entirely to the cells of 
the posterior cornua, about which greater difference of opinion exists. Bidder and 
his followers deny the existence of any true nerve-cells in the posterior cornua; 
in only one case did they observe a large nucleated cell with several processes in the 
gelatinous substance of the cord of a dog.t Figs. 6, 7 show the relative size and 
frequency of these cells, and as these two figures are drawn to the same scale as Figs. 
4, 5, from the anterior cornua, they will serve for comparison; they are all drawn 
from the lumbar enlargement of the calf. For convenience of description, I shall 
adopt Clarke's division of the posterior cornu into cervix and caput cornu, the caput 
being the broad expanded portion of the cornu, the cervix the remainder of the 
cornu as far forwards as the central canal. My observations on the cells of the poste- 
rior cornu, which were mostly made before I had seen Clarke's recent paper (1859), 
* Observations on the Structure of Nerve-Fibre. Quart. Jour. of Microscopical Science, January, 1860. 
f That other observers have differed from them, Bidder and Kupffer attempt to explain by the somewhat 
singular hypothesis,that on the one hand cells of connective tissue are liable to be mistaken for nerve-cells, 
and also=preparation by chromic acid “does not preclude the possibility, that, in cutting the section, cells should 
be torn from their natural situation, and transported to a locality where they do not belong or are not expected 
to appear.” (Loc. cit., p. 68.) This latter supposition, even if we could conceive of the possibility “that, in 
cutting the section,” cells could be stolen, and displayed with their processes spread out by the razor, might be set 
entirely at rest by making the section from behind forwards, in which case we might certainly infer that all the 
cells of the posterior portion belonged where they were seen, and the only inference it seems possible to draw 
is that the preparations of the Dorpat school are not sufficiently transparent for the display of these cells, 
which certainly require more delicate preparation than is necessary for the cells of the anterior cornua. 
