H
' i r
O B S E R V A T I O N S ON THE
Authors have ajfinued, that, in the ganglia, the ftraight courfe of the
nervous fibres is interrupted. By this they mean, that a nerve cannot be
traced from the place at which it enters the ganghon, to the place at which
it comes out from it*. Hence, it is evident, that any defcription they
have given of the manner in which the nerves divide, after entering the
ganglion, of the courfe they purfue witliin it, or of tlie new combinations
they form before they go out of it, muft be confidered as mere hypothefes.
I firft examined the furface of the ganglia; and afterwards cut them,
and the nerves entering or going out from them, longitudinally.
On the furface of the ganglion I could trace, diftinflly, many of the
nervous cords, from their firft attachment to the ganglion, till they parted
from it, without any fubftance intervening of a diiFerent texture from that
of the nervous cords clfewhere -f.
Where two or more nervous cords entered one end of a ganglion, and
two or more were produced from the other end of it, I could plainly perceive,
that the nerves, in their courfe upon the furface of the ganglion,
after dividing into fmaller, were again colleded into larger cords, in fuch
a manner, that every nerve that came out of the ganglion confifted of
fibres from two or more of the nerves which entered into the ganglion J.
In the ganglia, and nerves conneSed with them, which I had cut open
length-ways, I could perceive, in every part of the ganglia, nerves diftinguiihablc
' Dr Haller, in Pr. Lin. Phyf, § 364. gives the following account of the ganglia, ' Duri nempe
' tumores nen'ei, incertae haftenus aut fabricae, aut utilitatis, in quibus iibraram nervearuni reftitudo
' interrumpitur.'
t See Tab. XX. Fig. 3. Tab. XXU. Fig. i. 2. 4. j .
t Sec Tab. XX. and XXII.
N E R V O U S S Y S T E M . 53
guilliable by their joints, which I could trace to or from the. cords of nerves
connefted to the ganglia; fo that the fibrous jointed texture, proper to the
nerves in other parts of their courfe, was neither loft, nor changed, within
the ganglia, into a fubftance quite different from nerve
The jointed fibres within the gangha have, however, in their interftices,
or feem covered and incrufted by a quantity of hard fubftance, of a yellowjfli
colour, in the ox, and in fome of the human ganglia, as that in the
trunk of the fifth pair, but rather of a reddilh brown in the greater number
of the ganglia in a man, upon which many blood-veffels are difperfed
t-
T. I V .
THE cords that come out from the under end of a ganglion are genei'ally
larger tlian thofe which go in to the upper end of it, as authors J have
remarjced; thus, the nerves ifluing from the femilunar ganglia, feem much
more bulky than the rami fplanchnici which go into them ||. But in the
courfe of the fympathetic nerve we fee, in fome places, exceptions to this
rule.
THE laft, and not leaft remarkable, obfervation to be made concerning
the ganglia, and nerves conne£led with them, is, that, although the greater
number of nervous threads do, perhaps, run in the direftion fuppofed
by authors, that is, from the head downwards to the feet, yet every nerve
conneded with a ganglion, appears to contain cords, running in oppofite
direftions, afcending, for inftance, and defcending. Or where nerves are
connciled to the upper, under, and outer part or fide of a ganglion, which
O is
• See Tab. XX. Tab. XXI. Tab. XXII. Tab. XXUI.
See Tab. XX. Fig. i. 3. 4. Tab. XXII. Fig. 6.
t Mechel, M. de I'Acad. a Berlin, 1749. p. 95. § 19.
II See Tab. XXD. Fig. 5.