constituting a system of nerves distinct from
and independent of the cerebro-spinal system.
Under the term sympathetic, he includes not
only the sympathetic, commonly so called,
but also the ganglia which occur on the pos-
terior roots of the spinal nerves, as well as
those which are present on several of the
cerebral nerves. All the finer nerve fibres
are regarded by him as sympathetic fibres.
These originate in the different ganglia ; some
of them pass inwards to the viscera, over
whose movements and nutrition they preside,
while others pass along with the cerebro-
spinal nerves to the extremities, and serve as
the nerves of nutrition to these parts. Each
of the ganglia he regards as a nervous centre.

* Anatomie et Physiologic de Systeme Xerveux,
tome ii. p. 5G9. et seq.

j- Observat. Anat. et Microscop. de Systemat.
Nerv. Structural, Berlin, 1838.

J Edinburgh Medical and Surgical Journal, July,
1846, &c.

Wagner's Handworterbuch der Physiologic
Zehnte Lieferung, p. 499.



SYMPATHETIC NERVE.



457



By the term centre, Volkmann seems to mean
an organ which serves as a regulating appa-
ratus, and by which several separate and
simple acts are combined into a single com-
plex organic act. The contraction of a muscle
is a simple act ; in the act of respiration we
have the contractions of many muscles com-
bined into a single complex act, their com-
bination being dependant on a power situated
in the medulla oblongata, which part of the
nervous system is therefore termed their cen-
tral organ. The question then in regard to
the independence of the sympathetic is, whe-
ther, in the sphere of the organic nerves,
there be such combinations, and whether these
have their centre in the brain and spinal cord,
or in the sympathetic. The brain is the centre
of all psychical acts ; it is therefore evident
that the sympathetic, in so far as regards all
the phenomena of sensation occurring in its
sphere, must be regarded as dependent on the
brain. But after the brain and spinal cord
have been destroyed, does the sympathetic
still remain active, and in such a state of
activity as implies the co-operation of a cen-
tral organ ? Muscular motion implies the
activity of the motor nerves, and the activity
of those muscles which are supplied by the
sympathetic must imply the activity of sym-
pathetic nerve fibres. The action of the
heart, however, as well as the circulation,
sometimes continues for weeks after the de-
struction of the central masses of the nervous
system. Thus Bidder removed with great
care the arches of the second cervical ver-
tebra, so that little blood was lost during the
operation, and then completely destroyed the
spinal cord. Frogs treated in* this way often
lived six weeks, sometimes ten, the circula-
tion, as seen in the web of the foot, remain-
ing at the same time active, and not differ-
ing from that in uninjured frogs. The heart
beat powerfully and quickly: in a freshly-
killed frog, in winter, the heart pulsated thirty-
fiva times in the minute ; while in a frog, the
spinal cord of which had been destroyed
twenty-six days previously, the pulsations
were forty per minute. When the brain and
spinal cord were destroyed, the medulla ob-
longata being left, frogs were retained in life
until the sixth day ; and when the entire cen-
tral organs of the nervous system were re-
moved, they lived until the second day; the
rapidly ensuing death in the latter case being
due, according to Volkmann, to the effects
produced upon the respiration. Within a few
weeks after the destruction of the spinal cord
the muscles of animal life were found to have
lost their irritability in a marked degree, and
still later no contraction could be produced
in them by application of chemical or me-
chanical stimuli ; the heart, however, in such
cases still continued to pulsate eleven times
in the minute, and retained its property of
responding to external stimuli. The intes-
tinal canal, in like manner, retained its irrita-
bility ; application of stimuli giving rise to
contractions which were sometimes of a local
nature, at other times extended for a con-



siderable distance on either side of the part
stimulated. Digestion, in like manner, suffers
but little from destruction of the central
parts of the nervous system ; healthy frogs,
and others, which had been operated upon,
were, after being starved for a considerable
time, fed with worms, and kept in separate
glasses. In the one, as well as in the other,
the worms were found after twenty-four
hours to be fully digested, and the stomach
and duodenum were filled with coloured
mucus ; such was observed to be the case
even in animals whose spinal cord had
been destroyed twenty-six days previously.
The secretion of urine also continues : when
in animals in which the brain or spinal cord
had been removed, the bladder was emptied
by external pressure upon the walls of the
abdomen, in a short time it again became filled
and distended to an enormous size, unless
emptied in the way just mentioned. It had
been observed by Valentin and Stilling that
after destruction of the spinal cord in the
frog, different derangements in the nutritive
processes ensued ; there were frequently ob-
served dropsical swellings, especially of the
limbs. On these also, sores formed, which
often penetrated as far as the bones. In re-
ference to these results, Volkmann states
that they are, as shown by Bidder, chiefly
accidental. Bidder found that when the
bottom of the vessels in which the frogs were
kept was covered, not with water, but with
moist grass or moss, no such degenerations
ensued. The rapid death which ensues in
warm-blooded animals, when operated upon
in the above manner, depends, according to
Volkmann, upon the difficulty of sufficiently
keeping up the respiration by artificial means,
as well as upon the loss of blood and diminu-
tion of animal heat. The circumstance, then,
that a certain number of the vital phenomena
disappear suddenly and irrevocably after de-
struction of the spinal cord and brain, while
others continue for a greater or shorter
time, and this very perfectly, can only de-
pend, according to Volkmann, upon the cir-
cumstance that the brain and spinal cord is
a necessary condition for the existence of the
former, but not for that of the latter. If the
latter depend upon certain nervous organs,
and if the nerves of the vegetative organs do
not require, as a fundamental condition of
their activity, the presence of the brain and
spinal cord, the only possible centres on which
they can depend for this are the ganglia of
the sympathetic. The sympathetic and its
ganglia, then, constitute, according to Volk-
mann, an independent whole, from which
proceed the impulses to as well as the regula-
tion of those actions which continue after
the brain and spinal cord have been destroyed,
and which notwithstanding require the co-
operation of a central organ. That the move-
ments in question require such an organ, and
are not produced by the mere stimulus of the
blood, faeces, air, &c., in the same way as the
twitchings of the muscles in a frog's leg are
produced by galvanism, is shown, according



458



SYMPATHETIC NERVE.



to Volkmann, by the different characters ex-
hibited by the two. When stimulus acts im-
mediately on motor nerve fibres, contraction
ensues only in that muscle or part of the
muscle to which these are distributed ; when
it affects the whole trunk of such a nerve,
many muscles are excited to contraction ; the
contraction so produced, however, is a mere
quivering, quite different from the combined
and plan-like movements of the muscles of
respiration, &c., or those reflex movements
which are produced artificially. In these,
there is a certain unity and plan, in the others
not ; the difference depending on the circum-
stance that in the one a regulating principle
associates the muscular movements for the
attainment of an organic object or purpose ;
in the others this does not take place. When
the regular and plan-like manner in which
the pulsations of a heart removed from the
body take place, is compared with the tu-
multuous and purposeless quiverings of a
diaphragm similarly circumstanced, it is hardly
possible to suppose that the two kinds of
movement proceed from the same principle.
Irritability acted on by the stimulus of the
blood, or air, might explain the mere con-
traction of the heart; the regular order, how-
ever, in which this takes place, implies the
existence of a regulating principle ; and a re-
gulating principle implies the existence of a
regulating apparatus. While the regular
movements of the voluntary muscles suddenly
cease when the brain and spinal cord are de-
stroyed, those of the organic muscles con-
tinue,'; and hence their regulating apparatus
cannot lie in the brain and spinal cord, and
can only, therefore, be situated in the ganglia
of the sympathetic.

The heart, according to Volkmann, is
more flabby after death than it is during life :
the intestines, in like manner, are collapsed in
the dead body, and appear like so many flat-
tened bands ; while in the living body, at least
in small animals, they present more the aspect
of tubes ; the looseness of the skin and of the
scrotum in the dead body is also remarkable,
compared with the appearance they present
in the living. These differences depend upon
a loss of tone. The tone of the involuntary
or organic contractile structures '!. does not,
however, depend on the brain or spinal cord,
inasmuch as it does not cease after these parts
have been destroyed, but may continue in the
amphibia at least for months thereafter. It
depends, according to Volkmann, upon the
sympathetic ; and from this he derives another
argument in favour of the view that the ac-
tivity of the sympathetic or ganglionic nerve-
fibres does not depend upon the brain or
spinal cord. After division of a motor nerve,
the muscles immediately became relaxed,
which shows, according to him, 1st, that the
tone depends on an active contraction of the
muscle ; 2nd, that the mere irritability of the
muscle is not alone sufficient for the restoration
of this contraction, but also requires an ex-
citing cause or motor impulse ; 3rd, that the
nerve conveys this motor impulse to the



muscle; 4th, that the place where this motor
impulse arises or originates is not the nerve
itself, but is a central organ. If now, after
destruction of the brain and spinal cord, the
tone in the organic muscles and many other
contractile tissues continues, it follows from
this that, besides the brain and spinal cord
there must still be another centre from
which motor impulses proceed, and this can
only be the ganglia of the sympathetic.

In regard to this question, so far as our
knowledge of the anatomical constitution of
the sympathetic extends, the most probable
view would seem to be that it is partly inde-
pendent, in its action, of the brain and spinal
cord, partly dependent. The circumstance
that there are present in its branches nume-
rous nerve- fibres which are derived from the
brain and spinal cord, would appear to indicate
that the organs to which such fibres proceed
must be to a certain extent influenced by the
central masses of the nervous system. From
the circumstance, however, that it probably
contains*other nerve-fibres which do not arise
in the brain and spinal cord, and more particu-
larly from the circumstance of gray nervous
matter being present in different parts of its
extent, it seems not unreasonable to suppose
that the influence which it exercises over the
parts towhich it is distributed originates, partly
at least, not in the brain or spinal cord, but in
the gray or ganglionic matter mentioned. If
we attribute to the gray matter of the brain
or spinal cord a certain property of originating
nervous force, it seems unreasonable to deny
similar properties to the gray matter occurring
in other parts of the nervous system. What-
ever properties are possessed by the one,
analogous properties are, it is to be expected,
possessed by the other. Besides, no other
hypothesis which has been proposed to ac-
count for the function of the ganglia appears
to harmonise so closely with known facts as
that which regards them as so many distinct
peripherical nervous masses endowed with
properties similar to those which are com-
monly attributed to a nervous centre.

Properties of fibres of sympathetic. Sensory
properties. In regard to the sensory pro-
perties of the sympathetic, different statements
are made by authors. Bichat, Magendie,
Dupuy,* and others, observed that section of
the branches of the sympathetic was attended
with few or no signs of pain. Dupuy states
that he has removed the superior cervical
from the horse without the operation appear-
ing to call forth any marked expression of
pain. Section of the sympathetic cord in the
neck may often be performed in the rabbit
without any indication of sensibility being
given. Haller found, on the other hand, that
irritation of the hepatic plexus in the dog gave
rise to distinct signs of pain : the same results
were also obtained by Meyer from irritation
of the solar plexus. When he made incisions
into the superior cervical ganglion, he found,
contrary to what had been observed by Dupuy,

* See Longet. op. cit. torn. ii.



SYMPATHETIC NERVE.



459



that clear indications of pain were elicited.
From ligature applied to the renal nerves, as
well as from the application of chemical or
mechanical stimuli to the semilunar ganglia,
animals suffered great pain. So, also,
Flourens* found that on irritating ,the semi-
lunar ganglion in dogs the animals exhibited
distinct signs of pain, and the same results were
obtained by Brachet f , from irritation of the
thoracic ganglia. Frequently, according to
Brachet, stimuli, when first applied to a part
of the nerve, do not give rise to pain ; after-
wards, however, when the part has been ex-
posed to the air for some minutes, if irritation
be now applied distinct signs of pain are
elicited. Longet J, in like manner, found that
on irritation of the semilunar ganglia the
animal almost invariably exhibited indications
of more or less pain being produced. In other
animals, where the lumbar ganglia were sub-
jected to experiment, he found, like Brachet,
that it was only after prolonged irritation that
signs of pain were evinced. So, also, accord-
ing to Valentin $, when the cavities of the
thorax or abdomen are opened as quickly as
possible, and pressure applied to the semi-
lunar ganglion, to the splanchnics, or to any
other branch of the sympathetic, sometimes
no signs indicative of sensibility are evinced.
When, however, they have been exposed to the
air for a short time they generally exhibit these
properties in greater or less degree. The
severe pain which frequently attends diseases
of parts supplied exclusively by the sympa-
thetic nerve, also affords still better evidence
than can be derived from experiments of the
existence of sensory nerve fibres in the sym-
pathetic.

Different parts of the nerve appear to
exhibit the property of sensibility in different
degrees. In regard to this point, Valentin jj
gives the following as the results of his ex-
periments. 1st. The very grey branches which
have passed through several ganglia do not,
when the stimulus applied to them is slight,
give rise to any signs which would indicate
that pain was produced. Such branches are
those which pass along the mesentery to the
intestine ; strong stimuli, however, such as
the application of a ligature or of chemical
irritants, cause, when applied even to these
branches, distinct signs of pain. 2nd. Irritation
of the ganglia themselves is followed by signs
of pain either immediately or after a short
time. 3rd. The connecting cord of the sym-
pathetic is similarly circumstanced in regard
to sensibility as the ganglia. 4th. The rami
communicantes are as highly endowed with
sensibility as the posterior roots of the neigh-
bouring spinal nerves. He found that section

* Rech. Experimental, sur les propr. et les Fonc-
tions du System. Xerv. p. 229., as quoted by Longet.

t Rech. Experiment, sur les Fonct. du Systeme
Xerv. Gangl. 2nd edit, Paris, 1837, p. 3o7., as
quoted by Longet.

t Op. "cit. ii. p. 566.

Lehrbtich der Physiologic des Menschen, 1844,
band ii. p. 421.

|| Op. cit. band ii. p. 422., as quoted by Longet.



of a communicating branch did not destroy
the sensibility of the corresponding ganglion :
the main cord of the sympathetic must also be
divided above and below the ganglion before
this ensues. In the lumbar region Brachet*
found that, when the communicating branches
of three successive ganglia were divided, the
central ganglion was deprived of its sensory
properties. The greater the number of ganglia
intervening between the point of the branches
of the sympathetic, to which the irritant is
applied, and the cerebro-spinal centres, the
less distinctly, according to Valentin, does it
give rise to signs of pain. Hence, the peri-
pheral branches are the least sensitive, while
the rami communicantes are the most highly
endowed with this property, the connecting
or main cord of the sympathetic and ganglia
being intermediate in this respect between
these two. The nature of the stimulus ap-
plied has also an influence on the results
produced : when the ganglia are merely pricked,
or their branches quickly divided, sometimes
no sign of sensibility is evinced, whereas
pressure, application of nitric acid or potash
to the same parts give rise to distinct expres-
sions of pain.

In regard to the experiments which are
made with a view to ascertain the sensory
properties of this nerve, it is to be observed
that in general it is only by application of
very powerful stimuli that the phenomena of
sensibility are elicited : they seem to act by
producing a more or less abnormal condition in
the part of the nerve to which they are ap-
plied, and hence the effects they produce may
be regarded as belonging to the same category
as the phenomena observed in diseased con-
ditions of the organs supplied by this nerve.
In the normal or healthy condition the fibres
of the sympathetic seem to be almost entirely
destitute of the property of communicating
impressions to the sensorium. We do not
know, as Volkmann observes, whether the
organic muscles be at rest or in motion ;
whether the glands secrete in larger or in
smaller quantity ; whether the gall-bladder be
full or empty. We are sensible of the impres-
sions made by the particles of food so long as
they remain in the mouth, but, as soon as they
reach the stomach or intestinal canal, we are
no longer aware of their presence.

Motor properties. That the sympathetic
contains motor nerve fibres there can be no
doubt ; irritation of its branches being followed
by movements in the different muscular organs
to which they are distributed. Thus irrita-
tion of the splanchnic nerves in the living
animal, or immediately after death, is generally
followed by more or less extensive contrac-
tions in the small intestine. Miiller observed
that the same result followed irritation of the
semilunar ganglion : the same observation has
also been made by Kiirschner.f Mechanical
or chemical irritation, but especially galvanic

* Op. cit. p. 360., as quoted by Longet.

f Abhandlungen ttber das Xerven System, von
M. Hall. Aus dem Englischen von D. C. KUrsh-
ner, Marburg, 1840, Xachtraege, p. 182.



460



SYMPATHETIC NERVE.



stimulus applied to the filaments of the sym-
pathetic which pass to the heart, have the
effect of accelerating the pulsations of that
organ and of exciting it to renewed contrac-
tion after it has ceased beating. As move-
ments very frequently arise in organs supplied
by the sympathetic, especially in the intestines,
spontaneously, at least under the stimulus of
the atmospheric air, it is sometimes difficult
to determine whether the contractions which
follow the application of a stimulus to any of
the nerves be really caused by this, or whether
they may not belong to those just mentioned.
Frequently, however, the contraction follows
the irritation so regularly as to leave no doubt
that the two are connected ; if, moreover, the
abdominal muscles in the cat or rabbit be
removed, so that the thin and transparent
peritoneum alone remains over the viscera,
application of mechanical or chemical irritants
to the splanchnic nerves in the thorax may
still be observed to be followed, in many cases
at least, by contractions in the intestine. In
such experiments the air is prevented from
acting upon the viscera by the intervening
peritoneum, and in this way the fallacy above
mentioned is less liable to occur.

It remains to consider the motor influence of
the sympathetic in reference to the different
muscular organs supplied by it.

Heart. The heart, as has been already
stated, derives its nerves from the sympathetic
and pneumogastric. That the branches which
are supplied by the sympathetic exercise an
influence over the movements of the heart, is
shown by what has been already stated, that after
it has ceased to beat, irritation of the branches
which pass to it from the cervical ganglia will
again excite it to contraction. Similar results
frequently follow irritation of the ganglia them-
selves. When the galvanic stimulus is ap-
plied to the cardiac branches of an animal in
which the heart has not yet ceased pulsating,
the effect is to augment the number of beats,
and at the same time to increase their strength.
In a rabbit in which the heart's action had
ceased, Valentin * found that when the
wires of the magneto-electric apparatus were
applied, about A of a millimetre distant from
each other, upon the second thoracic ganglion
of the right side, a very powerful contraction
in the auricles immediately ensued : the ex-
periment was repeated several times, and with
the same result. This also took place when
the same stimulus was applied to the first
thoracic ganglion. When, on the other hand,
the wires were laid upon the aorta at the dis-
tance of ^-th of a millimetre from the heart, or
upon the surface of the right ventricle, no effect
was produced. He concludes, therefore, that
the stimulus when applied to the nerves was,
in this case, more effectual than when applied
to the muscular fibres themselves. As regards
the function of those filaments which are sent
by the pneumogastric to the heart, E. H.
Weber f believes that they exercise a re-

* Loc. cit. p. 427.

f Wagner's Handworterbuch der Physiologic,
band iii., Abtheilung ii. p. 45.



straining influence over the movements of the
organ ; stimulus applied to the pneumogastric,
according to his experiments, having the effect
of retarding or altogether stopping its move-
ments. When the stimulus of the electro-
magnetic rotation apparatus was applied to
the bulbus arteriosus in the frog's heart, the
part of the organ around which the fibres
derived from the sympathetic are, according
to him, chiefly distributed, he found that the
pulsations were increased in number as well
as in strength. When, on the other hand,
the same stimulus was applied to the upper
portion of the inferior vena cava, where the
filaments of the pneumogastric are mainly dis-
tributed, the effect produced was not an ac-
celeration but a retardation or stoppage of
the heart's action. When a defined part of
the vagus has been stimulated for some time
continuously, the heart again begins to pulsate :
when a portion of the nerve above this point
is now stimulated, no effect is produced;
when, on the other hand, the stimulus is ap-
plied to a portion further down, nearer the
heartj a cessation of its movements is again
produced. The circumstance that the heart,
after the stimulus has been applied to the
pneumogastric for some time, again commences
to beat, is attributed by Weber to the part of
the nerve becoming exhausted, or losing its
restraining influence, when the heart, being
thus freed again, begins to pulsate. Budge*,
however, attributes the cessation of the
movements of the heart, produced by the
application of galvanic stimulus to the pneu-
mogastric, not to any restraining power ex-
ercised by that nerve, but rather to a
temporary exhaustion produced by the
strength of the stimulus. In support of this
view, he states that, although the movements
of the iris chiefly depend upon the oculo-motor
nerve, yet Weber found, when the wires of
the magneto-electric rotation apparatus were