The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1873-04-05 00:00:00

HR. LAWSON TAIT'S FOURTH

LECTURE.

THE NERVOUS 'SYSTEM.

This lecture was delivered on Friday, at the British
School-room, High-street, subject : "The Brain and
the Nervous System." This may be divided into four
Parts. First, the brain proper, or cerebrum. Sec-
ond, the little brain, or cerebellum. Third, the
spinal cord. Fourth, the nerves. Physiologists draw
a distinction between the mind, and the will. The
mind is that whole set of faculties by which we rea-
son, and remember facts on which to reason, and be-
come conscious of moral responsibility and so forth.
The will is the activity of the mind considered as
moving the bodily organism, that is, the muscles. It
is only with the will that we have here to do, and with
that part of the cerebrum in which it resides, and with
the cerebellum, spinal cord, and nervous system.
The lecturer began with the nerves, which hc des-
cribed as telegraph wires. They are simpler than the
brain, which may be called a galvanic battery;
simpler also than the spinal cord, which is made up
of switches of nerves. A nerve, when it arises near
one of the extremities, as at the tips of the fingers,
is a thin delicate band of whit. tissue. It is soon
joined by other such fibres, and so becomes a thick
cord. When we have the feeling of a foot being
"asleep," it results from the compression of the
sciatic nerve, near the hip-joint. If one of these
nerve-fibres be cut across, we find it made up of three
layers. Outside there is a thin layer of ueurileina,
which is to bind it in its place. Inside this, there is
a layer of albuminous white (the white substance of
Schwalm), which is the isolating medium. It covers
the nerve itselt, which is the conducting wire, and
accompanies it all the way up to the brain. This cor-
responds to the arrangement in the telegraph cable,
where we have copper wire within, then a sheathing
of tow, then gotta percha. There are two different
functions of the nerves—the sensory, and motor.
The latter is the response, sent from the brain, when
the former is received there. Reflex action is when
the response is sent without the direct consoions
action of the will, that is, from some higher part of
the nervous system, but not from the brain proper.
It is from the multipolar cells that these responses
originate. They are the starting points of the cen-
tral axis of the nerve-fibre. An example of this is
winking. The wind blows on the eye, or you see a
coming danger. This stirs the fibres of the optic
nerve, which run back into a cell, or rather a group
of cells, These send a message by the motor nerve,
to contract the muscles that move the eyelid. The
whole takes place without any direction from the will.
The nerves that convey the message to the central
cell are called afferent; those that take out the res-
ponse are called efferent. This reflex action takes
place mostly by the spinal column, independently of
the complex processes of the brain. In digestion,
the flow of gastric juice is a reflex action. Walking
is a reflex action, and 60 is blushing. The next point
of importance is the sympathetic, or more properly
the ganglionic system. Ganglia are collections of
multipolar cells, or, in other words, concentrations
nerve-fibre, which begin in the neck and go far dew!'
on either aide the spinal column, occurring in front of
each vertebra. The pneumo-gastric nerve, which
guides respiration, has relation to this system. The
spinal cord, which passes all down the back, is a coi-
-1 .ction of the nerves from the lower limbs. There
r. two kinds of nervous tisane, the white and the
g,,y. The white is the nerve-tibre ; the grey is the
cAI-matter of the multipolar cells. This last origi-
ns Ami nervous dorm The Wale Gomm iL We do

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not know s. _. nervous foree is. It is like electricity,
but is not the same. If I divide a nerve, and then
tie it, electricity will pass along, but not the nervous
influence. In the spinal cord, we have a mixture of
the two tissues. As they collect, the nerve-fibre loses
first of all its neurilems. Then we begin to lose the
white substance. A crossatection of the spinal srrd,
about the middle, shows two horn-like distributious
of the grey matter, imbedded in the white imater.
It receives (or gives off) a pair of spinal nerves at
each vertebra. Now each of these nerves arises oat
of it by two distinct roots ; one rooted iu the white
matter, and having to do with movements; the otter
in the grey matter awl having to do with pem.pthais.
If the back were broken in the middle, ino\:nients
might still take place in the limbs guided from below
the fracture, but they would be without will or con-
sciousness. After a frog's bead ham been cut it it
you place a drop of acid on his one foot, he vill brush
it off with the other foot, though there is nc pain and
no sensation in the case. For the apparatr,sis com-
plete in the vertebra (without reference to the brain)
as long as it is supplied with arterial blood.
The spinal cord may be defined as that part of the
apparatus by which the brain transmits I'4 action.
Almost all nerves pass through it, as the) are thus
tied up in a bundle for economy of space. It alll.
originates, as has been said, reflex acti.ns. The
meddle oblongata in the name given to t ) highest
part of the spinal cord, where it thickens a .1 extends
itself at the base us the brain. The sligh7e4 injury
to this produces instant death. This is Ile point
struck by the guillotine, which, therefore, is the toast
merciful form of capital punishment, more so than
hanging, which is a brutal process. Above this, we
come to the cerebellum, which is a large ganglion of
the grey matter at the back of the head. Its prob-
able use, as far as se know it, is to co-ordinate and
harmonise a large group of muscular movements, oc-
curring at the same time. Thus in the common
action of walking, though it seems so simple, about
twenty different muscles come into play, and their
actions have to be combined and harmonised. Of
the brain proper, or cerebrum, we know even less.
It is the great riddle of physiology. It is distributed
in long folds called convolutions, probably for the
sake of packing, and to provide a large extent of sur-
face where the white matter, expanding its fibres, crin
come into contact with the covering layers of ,the
grey matter. We find the two alternatiug thus—grey,
white, grey, white, grey, white—in six layers. The
brain is a two-fold organ, having a right and left side
' exactly corresponding. But the nerves from the right
side cross over to the left side of the body, and so
inversely. They have been called 'glands that
secrete thought." It is clear that the base of the
brain is more important than the higher part; for the
slightest injury calms death or idiocy, but not so
with the upper surface of the brain.
This point bears directly on phrenology; for
phrenology takes for granted that the upper surface
I of the brain is the important part, but it has really
no foundation. It only considers the forehead and
the top of the head, whereas the most important
organs are situated at the back of the mouth, and near
the throat. Besides, 'bumps" result merely front
' the thickness of the skull, which often varies very
' much in different portions. Mr. Tait stated that he
had observed the head of the notorious prisoner Dr.
Pritchard, of Glasgow, and found that it had a very
small bump of clestructiveuess. The plaster cast,
which was produced for phrenological purposes, had
not the faintest resemblance to him, and was a catch-
penny affair.
It is our duty as journalists to state the fact that
the diagrams and drawings at these lectares have
been imperfectly seen by a large part of the auditory,
owing to the inconvenience of the room for the pur-
pose of a lecture-room, a fact which has given rise to
re-iterated complaints.