56 O B S E R V A T I O N S ON THE
to Dr Meckel has appeared to afford fufEcient reafon for denying that
they ferve for fecretion, that, I apprehend, will evidently appear neceflary
to defend them from external violence, or the preffure of the mufcles and
other organs.
To which I would add an obfervation on the firft pair, or olfaftory
nerves, which feems to carry with it confiderable weight, to wit. That, in
man, the trunk of the olfaftory nerve has, adhering to its end, a cineritious
bulb, fituated within the cranium, and which is evidently of the fame
texttue with the cortical matter of the brain i". Now, in fith, I have found,
that the olfadory nerve has no fuch bulb within the cranium; but when we
trace that nerve forward towards the nofe, wdiich is, in them, at a great
diftance from the cranium, we find a ganglion, near the nofe, which fupphes
the place of this bulb, and from which more nerves come out than enter
in J.
Seventhly, We lhall more readily receive the opinion that the ganglia are
additional fources of nervous energy, if we are perfuaded, from what has
been before obferved, that every nerve is, in its courfe, covered with cineritious
matter, from which energy is added to it.
Eighthly, When we compare a lymphauc conglobate gland with a ganglion,
we remark a ftriking refemblance. The lymphatic veffels form a
net-work on the furface of thefe glands, in which we can readily trace their
whole courfe. Other lymphatics enter into the fubftance of the gland,
which, in its number of blood-veffels, its colour, and confiftence, very
much
• Mem. de I'Acad. des Sc. a Berlin, 1749, p. 91. Zinn and Haller adopt the opinion of Dr Meckel,
that the ganglia are not fources of nervous matter and energy, Mem. de I'Acad. a Berlin, 1753.
and Hal. El. Phyf. Tom. 4. P- 408.
t See Santorin, p. 62. Weitbrecht, WinHow, T. 4. § 133. Soemmering, de Bafi Enc. p. 89.
et Tab. i. and 3.
t See Tab. XXXII. Kg. .. K.
N E R V O U S S Y S T E M .
much refembles a ganglion : Thus, till we trace the fplanchnic nerves into
the femilunar ganglia, we are apt to miftake them for conglobate glands.
Yet no perfon who underftands the fubjefl can doubt, that, in the conglobate
glands, the arteries make a fecretion of matter, which is added to the
lymph, although the nature of that matter has not yet been fully afcertain-'
ed by experiment.
T. V i l i
UPON the whole, all the nerves which iffue from ganglia feem to be formed
by a combination of threads from many fources; and, befide thisj
the nerves, in their paffage through a gangUon, feem to receive new ener^
gy from the vafcular matter of the ganglion.
Hence we underftand the reafon why ganglia are moft numerous in the
nerves of organs of chief importance, as in thofe of the heart or of the inteftinal
tube. Thus, the inteftinal tube receives its nerves from the eighth
pair, and, perhaps, from almoft all the fpinal nerves. If the firft pair of
fpinal nerves had lain to the uppermoft part of that canal, and fo on, without
the intervention of gangha, by a wound or difeafe injuring the firft pair
of nerves, the uppermoft part of that canal fhould have totally loft the
power of afting; Whereas, if the threads are fuppofed to be intermixed in
the ganglia, we fhould, by fuch an accident, make a lofs of the thirtieth
part only of the power of the whole traS; which equable lofe would be attended
with much lefs danger than the complete lofs of power in the thirtieth
part of it.
Or in the heart, the lofs of one fourth part of the ftrength of all its four
principal facs would be lefs dangerous than a complete palfy of one of its
auricles or ventricles
P Whi l f t
• The three purpofes the ganglia are faid, by Dr Meckel, to ferve, Mem. de I'Acad. des Sc. a Berlin,
i>|.9. p. 96. To wit,
I. De diA'ifer un petit nerf en plufieurs nerfs i
3,- Di