708 NERVOUS SYSTEM. (Microscoprcat Anatomy or tas Nervous Cenrnes.) 
the direction of which is probably oblique or 
transverse, as considerable portions of them 
may be seen taking such a direction when a 
piece of grey matter, cut transversely, is exa- 
mined under the microscope. 
The grey matter of the cord contains caudate 
and spherical vesicles imbedded in their usual 
granular matrix. They are found in the horns 
as well as in the commissure. The caudate 
_ vesicles are most numerous, and distend in the 
anterior horn and at the root of the posterior 
one. The remainder of the posterior horn and 
the gelatinous substance which is found at its 
posterior border, resemble very closely in struc- 
ture the grey matter of the cerebral convolu- 
tions. 
By examining thin transverse sections of the 
cord, carefully hardened by immersion in 
spirits, a good view of the relative disposition 
of the grey and fibrous substances may. be ob- 
tained. Stilling has carried investigations of 
this kind to a great extent, and has published 
some beautiful plates, which are quite true to 
nature. Fig. 396 is copied from one of them. 
Fig. 396. 
Transverse section of human spinal cord, close to the 
third and fourth cervical nerves. Magnified ten dia- 
meters. ( From Stilling. ) 
Lb —— columns; #7, gelatinous substance of 
the posterior horn ; k, posterior root ; /, supposed 
anterior roots; a, anterior fissure; c, posterior 
fissure ; b, grey commissure, in which a canal is 
contained, which, according to these writers, ex- 
tends through the length of the cord ; g, anterior 
horn of grey matter containing vesicles ; e, an- 
tero-lateral column, from k to a. 
It is impossible, however, to obtain any 
information from such examinations, except 
of the most general kind. On referring to the 
figure, the reader will perceive several lines, of 
the same colour and appearance as the central 
mass, to radiate from each horn of the grey 
matter to the surface of the cord, and not only 
to its external surface, but to that of its fissures. 
At whatever part of the cord the section be 
made, whether on a level with the roots of the 
nerves or between their points of emergence, 
the same appearance of radiating lines is seen, 
and the radiation will be found to extend be- 
tween the central grey matter and whatever 
part of the surface of the cord the pia mater — 
comes into contact with. . 
Stilling and Wallach suppose that these line 
are continuous with the roots of the nerves; 
that they are, in fact, nerve-tubes proceeding 
from the grey matter to form these roots. But 
this supposition seems quite untenable, for th 
following reasons: 1st, because these lines an 
met with in situations intermediate to the poit 
of emergence of the nerves ; 2dly, because th 
pass to situations, such as the surface of t 
fissures, from which no nerve-roots emanalt 
3dly, because, if they were nerve-tubes, the 
could not be so distinctly seen with so low 
power. It is much more probable that th 
may be processes of grey matter prolonge 
wards the surface, to which bloodvessels n 
pass from the pia mater, or simply bloodves: 
passing from the pia mater to the grey matter. — 
some well-injected specimens, which Mr. Smee 
had the goodness to shew me lately, the bloo 
vessels were seen to take the sar 
direction and course as these lines. = 
Besides the pect erp ound 
considerable numbers in the grey matter, 
branching processes of the caudate vesicles ; 
met with in it also, which may be distinguish 
from the nerve-tubes by the absence of 
white substance of Schwann, by their greyi: 
colour, by their branching, and by their minut 
granular texture. Capillary bloodvessels ¢ 
met with in great numbers, ramifying in 1 
grey matter, where they are much more nt 
rous than in the fibrous matter. ’ 
Stilling and Wallach describe a canal passi 
through the centre of the grey commissure, ¢ 
extending the whole length of the cord. T 
is certainly visible in most regions, but no 
all. It seems to me to have much more 
appearance of a bloodvessel than of a car 
According to these authors, it is the persist 
condition of the much-talked of canal 
spinal cord referred to at a. previous page. 
Situation in the grey matter seems ral 
posed to this view. The point, howeve' 
one upon which I am not prepared to ex 
a decided opinion at present, and which 
serves more extended careful examination. 
From a review of the preceding statem: 
it is plain that a large number of fibres 
into the grey matter of the cord, and prol 
form some intimate connection with its 1 
elements; and this fact is favourable te 
supposition that the spinal nerves derive 
origin, at least partly, from the grey matter 
must be admitted, either that these fibres” 
with the vesicles of the grey matter in” 
way, or that they pass up to the brain thr 
the grey matter; the former seems thet 
reasonable supposition, and more cons 
with the apparent oblique or transverse” 
tion which the fibres take in the g 2 hee: 
The minute structure of the medulla 0 
gata resembles in many particulars that ¢ 
spinal cord. There is not, however, so ¢ 
plete an isolation of the fibrous matter in 1 
in the latter. Excepting in the anterior | 
mids, and quite on the posterior and lat 
surfaces, the two kinds of nervous substi 
