32 O B S E R V A T I O N S ON THE
C H A P T E R VI L
Of the Clneritious and Medullary Subftances of the Brain and
Cerebellum.
T . I.
T ^ H E brain and cerebellum, after the inveiling membranes are removed,
feem to confiil of t\yo fubftances, differing in colour and coniiftence,
called Cineritious and Medullary.
The cineritious matter is fofter than the medullary, and, in it, regular
ftrata or bundles of fibres are not obferved.
On the furface of the brain and cerebellum, many minute veffels pafs
from the pia mater into the cineritious fubftance; but the moil fuccefsful
injedion is far from fhowing, as Ruyfch and others have pretended, that
it is entirely compofed of veiTels. Yet, I have not, in any animal, obferved
in it regularly ihaped bodies which might be fuppofed glandular.
The cortical cineritious matter is fome^yhat, but not much, darker coloured
on the outer than upon the inner fide, where the medullary is joined
to it, or the one does not evidently appear to be gradually converted into
the other. It may not, however, be improper to obferve, that the cortical,
vafcular, and internal uriniferous parts of the kidney feem, to the
naked eye, the one to end, and the other to begin, almoft as abruptly.
E C T. II.
BESIDE the cineritious matter obferved in the cortical part of the brain
and cerebellum, or on the furface of the corpora ftriata, a great deal o.T it
N E R V O U S S Y S T E M . 23
is to be found inclofed within the medulla. For, as we conilantly obferve,
that fuch parts as arc cineritious without, are medullary within; fo we
may invert the propofition, and remark, that, if any tubercle is medullary
on the outer fide, we ihall, for certain, find cineritious matter within it.
Nay, in the middle fubftancc of the brain and cerebellum, halfway between
the furfaces of thefe and their ventricles, and even within the crura cerebri
and crura cerebelli, or the tuber annulare and medulla oblongata, which
are generally confidered as pure medullary cords, I have found a great
quantity of cineritious matter, into which, after a good injedion with vermilion,
I obferve many vefl'els penetrate, fo as to make the deep feated cineritious
matter as red as the cortical *. The numerous veffels, therefore,
which have been obferved to penetrate the medulla, ferve, befide, perhaps,
fome of the ufes conjeilured by authors, iff, To fupply the deep feated cineritious
matter; and, 2dly, In tlie cafes of lofs of fubftance of the cortex
by wounds, or otherwife, the veffels which run from within, outwards,
may not only furniih matter to nouriih the deep parts, but alfo to fupply
the lofs of the fuperficial, in the fame manner as when a bone has exfoliated,
the inner parts live, and the outer are, perhaps, in pait fupplied by the veffels
which run from the canal of the marrow, outwards, through the tables
of the bone.
C H A P .
' See Tab. VIL Fig. !.