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ESSAYS
ON
PHYSIOLOGY
AND
HYGIENE.
LIBRARY OF THE
^ fiHsbnrg Academy of Medieiie,
1 WOT TO BE EEMOVED.
PHILADELPHIA :
HASWELL, BARRINGTON, AND HASWELL,
1838.
A-
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CONTENTS
PAGE
1. An Experimental Investigation into the Functions of the Eighth Pair
of Nerves, or the Glosso-Pharyngeal, Pneumogastric, and Spi-
nal Accessory. By John Reid, M.D., &c. ....... 5
[From the Edinburgh Medical and Surgical Journal.]
2. Observations on the Structure hitherto unknown of the Nervous Sys-
tem in Man and Animals. By Professor Ehrenberg, of Berlin.
Translated, with Additions and Notes, by David Cragie, M.D. 67
[From the Edinburgh Medical and Surgical Journal.]
3. On the Combination of Motor and Sensitive Nervous Activity; or on
the Production of Sensations by Motions. By Professor Stro-
MEYER, of Hanover. Translated, with Additions communicated
by the Author, by W. Little, M.D 113
[From the Medical Gazette.]
4. Vegetable Physiology, 13.9
[From the British and Foreign Medical Review.]
5. Public Hygiene, 17*3
[From the Medico-Chirurgical Eeview.]
' ' '^^ .. : '
6. ' Exp'eriiftents on th^ &rain, -Spinal Marrow, and Nerves, .... 199
^ , XFronythe British and Foreign Medical K,e,v^v.]
7.' Vital Statistics, . . . . .■*^4f 209
'^J.I "•[From the Medico-Chirurgical Review.lj^
8. Progress of lh*ft.natomy and Physiology of the Nervous System
^ «r
vagum.
Exp. IX. — The glosso-pharyngeal, pharyngeal branch of the
par vagum, and constrictors of the pharynx, were exposed in a
young terrier immediately after a fatal dose of prussic acid had
been given. On pricking the glosso-pharyngeal no effect followed,
while convulsive movements of the constrictors of the pharynx
were very apparent on pricking the pharyngeal branch of the
par vagum. The wires of a pretty powerful galvanic trough were
then applied, and it was observed that when proper precautions
were taken to insulate the glosso-pharyngeal, so as to avoid the
passage of a current through the muscles, no movement was seen,
while very powerful convulsive movements of i\\e pharynx attended
each application of the wires to i\\e pharyngeal branch of ihe par
vagum. The nerves of the opposite side were then exposed. At
the first application of the galvanic wires to the glosso-pharyngeal
no movement followed. On repeating the application, slight irregu-
lar movements were observed in the middle constrictor, where
many o( the pharyngeal branches of the glosso-pharyngeal seem to
plunge themselves. The same extensive and vigorous movements,
as were observed on the opposite side, followed each application of
the wires to the pharyngeal branch of the par vagum. We were
afterwards satisfied that the slight convulsive motions seen on
irritating one of the glosso-pharyngeal nerves in this experiment.
16 REID ON THE EIGHTH PAIR OF NERVES,
could be accounted for by the transmission of a slight current
through the muscle, for in this case the trunk of the nerve was not
cut across, but merely raised on an aneurism needle. Now Mr.
K. T. Kemp (whose practical acquaintance with every thing relating
to galvanism is well known) to whom I referred the question,
stated to me that it was perfectly possible, nay probable, that a part
of the galvanism generated by a battery of twelve double plates,
each five inches square, such as was used in this experiment, would,
instead of passing across between the two wires, take the more
circuitous course along the circle, which was formed through the
muscle by the conducting nerve and cellular tissue. In fact, we
had demonstrative evidence that such was the case in this experi-
ment, for my friend Dr. J. Duncan, pointed out at the time, that if
the aneurism needle was allowed to touch the sterno-mastoid
muscle, strong convulsive movements of this muscle were excited,
though the needle was placed under the nerve a little posterior to
the part where the wires were applied.
Exp. X. — The glosso-pharyngeal nerve, pharyngeal branch
of the par vagum and constrictor muscles of the pharynx were
exposed in a young dog immediately after it had been deprived of
sensation by a fatal dose of prussic acid. Distinct convulsive
movements of the muscles of the pharynx were seen when the
pharyngeal branch of the par vagum was pricked by the forceps ;
no visible movement when the glosso-pharyngeal was similarly
treated. The nerves were then cut across, and galvanism applied
with the same results. The same observations were made upon
the nerves of the opposite side. Dr. Alison was present at this
experiment.
Exp. XI. — The nerves and constrictor 'muscles of the pharynx
were exposed on one side in a middle-sized dog, immediately after
it had been killed. Pinching the glosso-pharyngeal, wd^s followed
by convulsive movements of the upper part of the constrictors of
the pharynx, and stylo-pharyngeus muscle, but on separating a large
twig of the pharyngeal branch of the par vagum which lay below
it, and which was also embraced by the forceps, no effect followed
from irritating the glosso-pharyngeal alone. Pinching the pha-
ryngeal branch of the par vagum was followed by vigorous
movements of all the constrictors of the pharynx and stylo-pha-
ryngeus muscle. The same observations were repeated on the
opposite side.
In two other experiments convulsive movements in the stylo-
pharyngeus muscle and upper part of pharynx, such as was
observed by Mr. Mayo in the ass, followed the pinching of the
glosso-pharyngeal ; but in these the nerves had been cut through
hurriedly, and when covered with blood, so that it was afterwards
impossible to say whether the large ascending twig of the pharyn-
geal branch of the par vagum was included along with the glosso-
pharyngeal or not. The movements observed were such as in
other cases attended the irritation of that twig of the pharyngeal
GLOSSO-PHARYNGEAL NERVE. 17
branch of the par vagum. Recalling to my recollection these
facts, and the result of Exp. XL, I determined to repeat my obser-
vation in a more accurate manner.
Exp. XII. — The nerves and pharyngeal muscles were exposed in
a large Newfoundland dog, after receiving a poisonous dose of
prussic acid. The glosso-pharyngeal nerve was cut across and
galvanism applied, but this was so close to the communicating twig
of the pharyngeal branch of the par vagum, that no accurate ob-
servations could be made. The nerve was then rapidly but carefully
displayed on the opposite side without disturbing it, and it was
observed that when it was pricked with the forceps posterior to, or
on the proximal side of the point where it was joined by the
communicating branch, so often mentioned, no movement resulted :
on the other hand, the application of the forceps at a certain distance
anterior to or on the distal side of this junction, was followed by
convulsive movements of the upper part of the- pharynx. On
irritating the pharyngeal branch of par vagum, rapid and vigorous
movements of all the pharyngeal muscles and upper part of the
oesophagus followed.
Exp. XIII. — The difference between the effects of irritating the
glosso-pharyngeal, anterior and posterior to the junction of the
communicating branch, was also observed in this experiment per-
formed upon a young dog. The same extensive movements of the
constrictors of the pharynx and upper part of oesophagus were
again witnessed on pricking Wit pharyngeal branch oi par vagum.
On opening the anterior part of the 2]harynx, these movements
were also seen to extend to the muscles of the isthmus of the
fauces and soft palate, as indicated by the motions of those parts.
Irritation of the glosso-jjharyngeal was again repeated when the
pharynx had been opened, but still no muscular movement could
be detected.
The preceding experiments appear to me sufficient to prove
that the glosso-pharyngeal cannot be considered a motor nerve. I
am perfectly aware that negative are infinitely less conclusive than
positive experiments, and that one well-ascertained positive will
outweigh a whole host of negative experiments, so that if I had
been satisfied even in one of the ten experiments that muscular
movements followed the irritation of the glosso-pharyngeal, when
fairly insulated from the pharyngeal branch of thejoar vagum; or
if these experiments did not furnish a sufficiently plausible explana-
tion of the cause of the discrepancy between these results and those
obtained by Mr. Mayo upon the ass, I must have been compelled
to admit that the glosso-pharyngeal was also a motor nerve, though
to a limited extent. The conclusions I have formed regarding the
difference in function between the glosso-pharyngeal and pharyngeal
branch oiWiepar vagum are also greatly supported by their ultimate
distribution upon the pharynx and fauces, as I shall afterwards
point out when we come to the consideration of the functions of the
pharyngeal branches of thejoar vagum.
m 3
18 REID ON THE EIGHTH PAIR OP NERVES.
With regard to the argument in favour of the motor properties
of this nerve drawn by Miiller fronri its anatomy, it appears to me
that this analogical mode of investigation, valuable though it be^
must be permitted to yield to the more positive obsei"vations ob-
tained from experiments. Of the existence of the ganglion ju~
gulare N. glosso-pharyngi, which was first pointed out by Ehren-
ritter,* and more lately described by Miiller;! and of its apparent
limitation to the posterior filaments of the nerve, I am fully con-
vinced from actual examination. And though it must be granted
that this nerve here resembles very closely the double roots of the
spinal nerves, yet we must be wary in drawing analogies between
the glosso-pharyngeal and the spinal nerves, for we have another
ganglion situated immediately below this, viz. the ganglion petro^
sum of Andersch, which involves the whole trunk of the nerve;
and to this assuredly we have no analogical structure in the spinal
nerves, if we admit that the superior ganglion resembles those
upon their posterior roots, Miiller no doubt supposes that this
inferior ganglion differs from those placed upon the posterior roots
of the spinal nerves, and that it belongs to the sympathetic system.
But as nothing like conclusive proof is advanced in support of this
opinion, we may, in the meantime, reasonably suspend our belief
as to the probable influence which this lower ganglion may exert
upon the functions of the nerve. t
Since, then, we are led to believe that the glosso-pharyngeal is
entirely a nerve of sensation, and that the muscular movements
which result from its irritation depend not upon any influence
extending: downwards along the branches of the nerve to the
muscles moved, but to a reflex action exerted through the medium
of the central organs of the nervous system, we have next to inquire
whether or not these muscular contractions resemble any of the in-
stinctive associated muscular movements concerned in the Function of
Deglutition. It appeared to Dr. Alcock that they strictly resembled
the associated movements which are " ordinarily excited by a
disagreeable sensation experienced in the fauces and pharynx."§
There is little doubt that the muscles thus thrown into action
are those concerned in regulating the course of the ingesta along
the pharynx ; but I have not, after very frequent opportunities of
carefully watching this movement, been able to satisfy myself that
it resembled very closely any of the associated movements usually
engaged in this function. If asked, however, to w^hich of them it
most nearly approximated, I would say, to a rapid act of deglutition,
with this difference, that in the action of deglutition there is much
more extensive movements of the larynx and lower part of the
pharynx indicated by the ascent and subsequent descent of the
* Tiedmann's Zeitschrift fiir Physiol, Vol. ii. p. 175.
t Arch, fiir Anat.und Physiol. 1834. p. 11.
X Is it possible that the filaments which do not pass through the ganglion
Jugulare can be connected with the specific sensations of the fauces and pharynx ?
§ Op. cit. p. 264. .
GLOSSO-PHARYNGEAL NERVE. 19
hyoid bone and thyroid cartilage. I endeavoured in several of the
experiments, by gently pricking, pulling, and pinching the nerve,
to produce the more slow and usual effects of deglutition, or of those
"excited by disagreeable sensations in the fauces and pharynx,"
but without success. From what I have already said it appears
that the excitation of these extensive muscular movements is con-
nected with the pharyngeal portion of the nerve, and under the
term pharyngeal, I here include a great part of the filaments going
to the fauces. I am satisfied that this phenomenon is essentially
different from one of those rapid involuntary muscular movements
not unfrequently produced by the sudden excitation of pain. 1
have watched the effects of cutting and otherwise irritating some of
the superficial nerves of the cervical plexus which are exposed in
displaying this nerve, and I am convinced that they cannot be
classed under the same head. The muscular movements of the
throat and face observed on irritating the glosso-pharyngeal were
sometimes as well-marked when the animal was otherwise quiescent,
as when also attended by the general struggles of the animal. We
believe, then, that these pharyngeal filaments possess specific en-
dowments connected with the peculiar sensations of the mucous
membrane, upon which they are distributed, though we cannot
pretend to speak positively in what these consist. The apparent
difference in the endowments of the pharyngeal and laryngeal
branches might readily suggest some speculations upon the differ-
ences in the sensations of those portions of the mucous surface upon
which they are ramified, but from these we at present abstain.
The next subject of inquiry which naturally presents itself is,
what effect has section of the glosso-pharyngeal nerve upon the
functions of deglutition^ I certainly supposed, after witnessing
these extensive movements of the muscles of the throat and lower
parts of the face, excited by irritation of the glosso-pharyngeal,
that upon this nerve must depend those sensations of the fauces and
pharynx which give rise to the associated movements of deglutition.
I therefore fully anticipated that section of this nerve would
seriously interfere with the proper performance of these functions ;
and it was only after I could no longer resist the facts ascertained
by my subsequent experiments, that I reluctantly abandoned the
idea. The chief embarrassment experienced in arriving at satis-
factory results on this point, was the great difficulty of dividing the
nerve before it had given off any of its branches. To display the
trunk of the nerve became to us a comparatively easy process ; but
to cut it close to the foramen lacerum, and before it had given off
any of its twigs, remained to the last a matter of great perplexity.
It was only after repeated failures that we fairly succeeded in
effecting this on both sides, and I was never fully satisfied that the
nerves were satisfactorily divided, until I had carefully dissected
the parts after the death of the animal. After we had succeeded in
exposing the trunk of the nerve, and traced it back to the neighbour-
hood of the foramen lacerum, it was always necessary to proceed
20 REID ON THE EIGHTH PAIR OP NERVES.
with great caution, as it here lies in close apposition with the trunks
of the par vagum, spinal accessory, hypoglossal, and the sympa-
thetic; and when to the difficulty of separating parts thus placed so
closely to each other, and lying at the bottom of a deep wound, we
add the obscurity so frequently arising from the blood poured out
from the division of the numerous small vessels surrounding these
nerves, and the frequent and violent struggles of some of the
animals whenever the glosso-pharjaigeal was seized by the forceps ;
some notion may be formed of the difficulty of succeeding in this
attempt. I ascertained that several of the animals in which all the
branches of the nerve had been fairly divided, except one or two of
the small twigs going to the pharynx, could nevertheless sWallow
perfectly in from ten days to a fortnight, in other words, after the
pain and swelling arising from the incisions had considerably
abated. As, however, I had seen equally vigorous muscular move-
ments excited by pinching one of the pharyngeal twigs, as from
the trunk of the nerve itself, I considered these unsatisfactory.
In three dogs, which lived long enough after the perfect section of
the trunk on both sides, to enable me to make decisive observations,
the power of swallowing was perfectly retained. The most satis-
factory of these I shall here shortly detail.
Exp. XIV. — The glosso-pharyngeals were divided in a middle-
sized young terrier. This animal recovered rapidly from the effects
of the operation, and a few days after it swallowed small morsels
readily. Ten days after it swallowed large masses with great
facility, notwithstanding the wounds in the neck were still open.
Fourteen days after the operation it was repeatedly tried with
morsels of various sizes, and there could be no doubt that he swal-
lowed large masses quite readily and as perfectly as ever he did.
These observations were again repeated to the perfect satisfaction
of all those present. It was then killed, and a careful dissection
made of the nerves experimented on. The upper cut ends of the
glosso-pharyngeal nerves were found lying within the foramen
lacerum, and not a single filament arose from either nerve above the
point where they had been divided. More than an inch of each nerve
had been removed. This last experiment, being a positive one, is
alone sufficient to decide, independent of the other two which I
might also detail, that the glosso-pharyngeal is not the sole nerve
upon which the sensations of the fauces and pharynx necessary to
the act of deglutition depend, though I believe there can be little
doubt, both from its extensive distribution upon the mucous sur-
faces of these parts, and from the evidence afforded by the experi-
ments upon the effects of pinching its pharyngeal branches that
it must be concerned in exciting those sensations. Other nerves
of sensation are distributed upon these surfaces, viz. the descending
palatines of the second branch, and a few filaments from the lingual
portion of the third branch of the fifth, upon the mucous membrane
of the soft palate and isthmus of \.\\q fauces ; and branches of the
laryngeal nerves, but principally of the superior laryngeal upon
GLOSSO-PHARYNGEAL NERVE. 21
the mucous membrane oii\\Q pharynx. What would be the result
of cutting all these nerves, I have not yet attempted to ascertain,
but having first satisfied myself that section of the superior laryn-
geals does not interfere with the act of swallowing, I performed the
following experiment.
Exp. XV. — Both the glosso-pharyngeals and superior laryn-
geal branches of the par vagum were cut in a stout terrier dog.
Shortly after the operation he swallowed several pretty large mor-
sels of animal food quite readily. Next day he also swallowed two
or three pretty large morseLs in such a manner as to satisfy me that
if the swelling and inflammation were subdued, his powers of deglu-
tition would not be impaired. On the third day he was seized with
pneumonia, and died before any other accurate observations could
be made. On dissection, these two nerves were found to be satis-
factorily divided on both sides. This experiment was repeated
upon another dog, but this animal died two days after, without even
attempting to swallow. I, however, feel so confident, from what
I saw in the first dog, that the section of both these nerves would
not affect the associated movements of deglutition, that I have not
thought it necessary to repeat the experiment. The inference to
which these experiments naturally lead us, is, that when the palatine
branches of the fifth pair are uninjured, these are sufficient of them-
selves to furnish the sensations upon which the associated muscular
movements of deglutition depend.
The results thus obtained regarding the efiects of section of the
glosso-pharyngealupon the function of deglutition differ considerably
from those observed by Dr. Alcock, for, according to that gentleman,
in those instances in which the nerve was perfectly divided "the
deglutition was so much interfered with as in some cases to be im-
possible,"— "it (the animal) often experienced so much difficulty
as to become much exhausted, or to seem even in danger of suffo-
cation before itsucceeded."* Theexperimentswhich I havedetaiied
above, are sufficient to show that these effects are not the necessary
consequence of the perfect section of these nerves. And as the
results obtained by Dr. Alcock were only observed by me when
ihQ pharyngeal hrdinch oi the, par vagum was divided, never when
it was left uninjured ; and as I shall afterwards show, that the seC'
tion of this nerve alone is sufficient to produce these effects, I am
irresistibly led to conclude that this gentleman must have divided
that nerve along with the glosso-pharyngeal. Indeed this might be
inferred from his own words, for in criticising the experiments of
Panizza, and attempting to point out the sources of error, by which
he supposes he must have been misled, Dr. Alcock describes the
glosso-pharyngeal in such a manner, as to leave no doubt in my
mind, after frequent and careful dissection of the parts, that his
pharyngeal branch of the glosso-pharyngeal is really ihe pharyn--
geal branch of the par vagum. As I have already pointed outj
* Oper. cit. 261.
3*
32 KEID ON THE EIGHTH PAIR OF NERVES.
the relation of these two nerves to each other is so close, that it is
only by frequently tracing them to their origin, that we are able to
distinguish them readily in all cases.
It is unnecessary to state how much these experiments are at
variance with the opinion of Sir C. Bell, that the function of this
nerve is to associate the movements of the tongue and pharynx
with the muscles of respiration in the instinctive movements of
deglutition. It is obvious from the experiments already and to
be subsequently mentioned, that these associated movements of
the tongue must depend upon the hypoglossal, and those of the
pharynx upon i\\e phai'yngeal branch of the par vaguni. Mr.
Shaw states,* "that the powers of this nerve over the pharynx has
been shown by several experiments, the results of which are very
curious, and corroborative of the views (viz. of combining the
movements of the tongne and pharynx) deduced from comparative
anatomy." What these experiments were we are not informed ;
but it must be obvious from those related above, that the derange-
ments of these movements were not necessarily connected with
lesion of this nerve. Besides, the anatomical fact, that the lingual
portion of this nerve is distributed entirely, or almost entirely to
the mucous surface of the tongue, is sufficient to entitle us to call
in question its alleged motor powers over that organ, if it is sup-
posed by the supporters of this opinion to act as a motor nerve.
We have lastly to inquire in what manner the section of the
glosso-pharyngeal nerve aflfects the Sense of Taste. My observa-
tions on this head are in perfect accordance with those of Dr.
Alcock. Dr. Alison had an opportunityof witnessing the persistence
of the sense of taste in one of the dogs, after a portion of the trunk
of the nerve on both sides had been removed, and Dr. Sharpey was
perfectly satisfied that the animal, the subject of Exp. VI. was suf-
ficiently sensible of disagreeable impressions upon this sense. And
though in the case witnessed by Dr. Alison a few pharyngeal fila-
ments, and in that witnessed by Dr. Sharpey one pharyngeal twig
on one side, were found to have been left uncut, yet it was obvious
that the rejected morsel sprinkled with coloquintida was fully
recognized before it passed beyond the anterior part of the mouth.
I need not add, that the lingual portion of the nerve was fully di-
vided in both of these cases. The remark, however, was repeatedly
made, (and it is of importance, as explaining the error of Panizza
on this point,) that if animal food was ofl!ered, and the dog very
hungry, he would eat the morsel containing the coloquintida rather
than lose it ; though he refused it if he saw any prospect of procuring
another free from the bitter. The subject of Exp. I., in which, as was
stated, the glosso-pharyngeal was cut on one side only, even eat readily
several piecesof bread diptin a strong infusion of gentian root. Lest
any doubt may arise that the presence of a few pharyngeal branches
could have influenced the sense of taste, I may adduce the subject
of Exp. XIV., to prove that when the nerve is divided before it
* London Medical and Physical Journal, Vol. xlix. p. 453.
i GLOSSO-PHARYNGEAL NERVE. 23
has given off a single filament, still the animal retains a sufficiently
acute perception of disagreeable savours. I have fed that dog with
morsels of animal food from my hand ; and after he had taken se-
veral morsels in this way, which he readily swallowed, I. then pre-
sented a morsel similar in size to the others, and with the coloquin-
tida concealed in a way that he could not see it, but no sooner was
it taken into the mouth, than it was rejected with evident symptoms
of disgust. This was repeated more than once. I find that Miiller
in the second No. of his Archives for this year (1837) states thatsome
experiments were performed in Berlin, in the summer of 1836, by
a Dr. Kornfeld, in which persistence of the sense of taste was ascer-
tained after section of this nerve. It is very probable, nevertheless,
that this nerve, though not the special nerve of the sense of taste, as
supposed by Panizza, Dr. M. Hall and Mr. Broughton* may yet par-
ticipate in this function, along with the lingual portion of the third
branch, and the palatine twigs of the second branch of the fifth pair.
This view is not only supported by the anatomical fact, that the
mucous membrane and papilise of the tongue, for about an inch in
front of \\-\Q foramen caecum, are almost entirely supplied by this
nerve, but also by the experiments of Dr. Alcock.t I endeavoured
to ascertain the state of the sensibility, and of the sense of taste in that
portion of the tongue where this nerve is ramified, after the trunk
had been divided on both sides ; but from the restlessness and
struggles of the animals, I was unable to arrive at any satisfactory
results.
From a review of all the experiments which I have performed
upon the glosso-pharyngeal nerve, I am inclined to draw the fol-
lowing conclusions :
1. That this is a nerve of com.mon sensation, as indicated by
the unequivocal expression of pain by the animal, when the nerve
is pricked, pinched, or cut.
2. That mechanical or chemical irritation of this nerve before it
has given ofi'its pharyngeal branches, or of any of these branches
individually, is followed by extensive muscular movements of the
throat and lower part of the face.
3. That the muscular movements thus excited, depend, not upon
any influence extending downwards along the branches of the nerve
to the muscles moved, but upon a reflex action, transmitted through
the central organs of the nervous system.
4. That these pharyngeal branches of the glosso-pharyngeal
possess endowments connected with the peculiar sensations of the
mucous membranes upon which they are distributed, though we
cannot pretend to say positively in what these consist.
5. That this cannot be the sole nerve upon which all these sensa-
tions depend, since the perfect division of the trunk of the nerve
on both sides does not interfere with the perfect performance of the
function of deglutition.
* Sixth Report of British S. Association. f Op. cit.
24 REID ON THE EIGHTH PAIR OF NERVES.
6. That mechanical or chemical irritation of the nerve, imme-
diately after the animal has been killed, is not followed by any
TYiuscular movements, when sufficient care has been taken to in-
sulate it from \h^ pharyngeal branch of the par vagum. And
we here again observe an important difference between the move-
ments excited by irritation of the glosso-pharyngeal and those of
a motor nerve. For while the movements produced by the irrita-
tion of the glosso-pharyngeal are arrested as soon as the functions
of the central organs of the nervous system have ceased, those from
irritation of a motor nerve, such as ihe pharyngeal branch of the
par vagum, continue for some time after this, and when all con-
nection between it and the medulla oblongata has been cut off.
7. That after perfect section of the nerve on both sides, the sense
of taste is sufficiently acute to enable the animal readily to recognize
bitter substances.
8. That it probably may participate with other nerves in the per-
formance of the function of taste, but it certainly is not the special
nerve of that sense.
Lastly, the sensation of thirst, which is referred to \.\\q fauces
d^ndi pharynx, does not appear to depend entirely upon the presence
of this nerve. The animals in which it was divided lapped water
of their own accord. I observed one of them in which the nerves
were found satisfactorily divided, rise, though very feeble, walk up
to a dish containing water, lap some of it, and return again to the
straw upon which he was previously lying.
To Dr. J. Duncan and Mr. J. Spence, 1 am most deeply indebted
for their valuable assistance in the performance of these experiments
upon the glosso-pharyngeal nerve and the greater part of those which
are to follow. It is obvious, that without the aid of active and
intelligent assistants, it would have been perfectly impossible to have
proceeded with such an investigation. These two gentlemen wit-
nessed the facts stated in the preceding experiments, and I have their
sanction for their accuracy.
PART II.
Pneumogastric Nerve.
I SHALL first consider the immediate effects of the mechanical and
chemical irritation of that part of the trunk of this nerve which lies
in the neck, and then proceed to the separate investigation of the
functions of lis, pharyngeal, laryngeal, oesophageal, cardiac, gas-
tric, and pulmonary branches.
I have exposed the trunk of the par vagum in the neck in at
least thirty animals, and in almost all of these, the pinching, cutting,
PNEUMOGASTRIC NERVE. 25
and even the stretching of the nerve were attended by indications
of severe suffering. It was frequently difficult to separate the nerve
from the artery, on account of the violent struggles of the animal,
though some of them had been pretty quiet during the previous
part of the operation. It has appeared to me, however, that a con-
siderable degree of stretching and even compression may in many
cases be exercised, without exciting any apparent suffering, when
these are gradually applied. And this may perhaps account for the
statement of Dr. M. Hall and Mr. Broughton,* that "in pinching the
par vagurn neither of the phenomena above-mentioned (viz. sensibi-
lity and muscular movements) occurs." Very few of the numerous
experimenters upon ihe, par vagum say any thing about the sensi-
bility of this nerve, apparently, because their investigations were
almost always conducted with a view to ascertain the effects of its
section upon the circulatory, respiratory, and digestive functions.
I find, however, that Haller, in some experiments expressly under-
taken for the purpose of ascertaining the degree of sensibility pos-
sessed by the nervous trunks, observed unequivocal signs of suffer-
ing on injuring the pneumogastric nerves. In relating an experi-
ment upon a rabbit, he says, " Utcunque nervorum octavi paris,
resecuimus, miseris cum doloribus, et contorsionibus animalculi."t
Again, in describing the effects of the application of a ligature upon
these nerves in another rabbit, it is mentioned, " ejulavit inter vin-
ciendum miserum animal. "f Brunn, in detailing several experi-
ments, upon the effects of including ihe par vagum in a ligature,
describes the animals as giving undoubted evidence of feeling pain.§
Dupuy states, in giving the details of one of his experiments, that
"I'animal temoigna beaucoup de douleur pendant la division du
nerf|| Dumas also, in relating an experiment upon this nerve,
informs us, that when " on passe ensuite une ligature autour du nerf
pneumogastrique ; il temoigna par ses mouvements et par ses cries
la vivacit6 de sa douleur." IT It is stated by Dr. M. Hall and Mr.
Broughton,** that when the compression of this nerve is continued
" for a few moments, an act oi respiration and of deglutition fol-
lows with a tendency to struggle and coughP I have frequently
repeated this experiment; and though in some of the animals pow-
erful respiratory movements were produced by compressing the
nerve, which were soon followed by struggles, yet I have never
observed either any tendency to cough or any act of deglutition,
which I could fairly refer to this cause. The most satisfactory of
these experiments I may here shortly relate.
Exp. XVI. — The pneumogastric nerves were exposed in a mid-
* Reports of British S. Association, Vol. iv. p. 677.
t Opera Minora, Tom. i. p. 360. Exp. 136. Laus. 1762.
X Oper, cit. Tom. i.p. 359. Exp. 132.
§ De Ligaturis Nervorum, Ludwig, Tom. ii. Scrip. Nov. Min. Sel. p. 285-6-7.
II Journal de Medecine, Chirurg. &c. Dec. 1816. p. 359. Exp. iv.
\ Journal General de Medecine, Tome xxxiii. p. 356.
** Oper. cit. 677.
26 REID ON THE EIGHTH PAIR OF NERVES.
die-sized mongrel dog. On laying hold of the nerve with the for-
ceps, rather gently at first, but soon increasing the pressure so as
to squeeze it pretty firmly, no effect was observed for a few seconds,
but the breathing then became somewhat heaving, with a noise
resembling snoring. This was repeated twice on each nerve, and
always with the very same effects. The struggles attending the
compression of the nerve in this animal were very slight.
Bichat contends that the increased respiratory movements ac-
companying the irritation of the par vaguTn depend solely upon the
sudden excitation of pain.* Unquestionably the sudden infliction
of pain hurries the respiration ; but I believe that there can be no
doubt that Bichat was in error, when, to this circumstance alone he
attributed all the increased respiratory movements observed on irri-
tating the pneumogastric nerves. In case it may be argued that
these increased respiratory efforts arise from the partial arrestment
of the movements of the glottis consequent upon compression of one
of these nerves, I may state that I have seen them in two cases when
the animal was breathing through a large opening in the trachea.
That these increased respiratory movements are not dependent upon
any direct effects which irritation of this nerve has upon the lungs
or thoracic muscles, is proved by the fact, that when the nerve is
cut across, the irritation of the portion in connection with the medulla
oblongata alone excites these movements.
Before proceeding to the consideration of the function of the
pharyngeal branches of the par vagum, I may here briefly advert
to the effects of section of \.\\q par vagmn upon the conjunctival
membrane of the eye, when practised upon those animals in which
the sympathetic is so closely connected to this nerve, that the one
cannot be divided without the other. I had several opportunities
of witnessing these on dogs. At a longer or shorter period, after the
trunks of ihepar vagum and the accompanying sympathetic nerves
were divided, the conjunctiva became red, swollen, and projected
over the cornea. The pupil was contracted, and only a small part
of the ball of the eye was seen between the half-closed eyelids.
This inflammation frequently went on to the secretion of purulent
matter, and afterlasting some time began gradually to abate. Petit was
the first who observed these effects upon the eye after the section
oiih&par ?;a^wm, and justly attributed them to the division of
the trunk of the sympathetic ; for he was perfectly aware of the
connection of this nerve with the sixth pair and first branch of the
fi.fth pair within the cavernous sinus, and of the intimate relation of
the trunk of this nerve with that of \he par vagum, in the neck in
quadrupeds.t Cruickshank also noticed this inflammation of the
conjunctiva in his experiments upon i\\Q par vagum. In the first
of these it is mentioned that there was " heaviness and slight inflam-
* Sur la Vie et la Mort, p. 316, 2d e \
-}• Memoire dans lequel il est detnonlre que les Nerfs Intercostaux fournissent
des rameaux, qui se portent les espirits dans les Yeux ; dans I'Histoire de I'Aca-
demie Royale des Sciences, Annee 1727.
PNEUMOGASTRIC NERVE. 27
mation of the eye," and in Exp. II., III., and IV., "the eyes," we
are told, " became instantly red and heavy."*
That Petit was right in supposing this inflammation of the eye to
arise from section of the sympathetic and not of the par vagum, has
been folly demonstrated by the experiments of Dupuy,t upon the
effects of the removal of the superior cervical ganglion of the sym-
pathetic. These experiments have been more lately confirmed by
Brachet. t This inflammation of the e5'e frequently takes place with
great rapidity after section of the sympathetic. In one case, I ob-
served the conjunctiva reddened a very few minutes after the opera-
tion. In two of Petit's experiments, it is mentioned that in a quarter
of an hour, after the section of the nerves, the cartilaginous mem-
brane, at the inferior angle of the eye, had encroached upon the
cornea. In the fourth experiment by Dupuy upon the horse, it is
stated, " Aussitot apres I'operation," the eyelids were swelled, and
the eyes watery. This inflammation appears to be confined to the
conjunctiva, — the contracted pupil and half-closed eyelids probably
depending upon the impatience of light generally accompanying this
condition. Petit mentions that he killed a dog on the third day
after the operation, and on dissection found the inflammation appa-
rently restricted to the conjunctiva. We do not, however, consider
it fairly ascertained that the inflammation is confined merely to the
surface of the eye. In the experiments of Dupuy and Brachet upon
the effects of the removal of the superior ganglion of the sympathe-
tic, to which I have referred, the same phenomena presented them-
selves, as far as the eye was concerned, as when the par vagum is
cut in the neck. This inflammation of the conjunctiva from section
of the sympathetic in the neck, cannot in all probability be referred
to the same cause as that arising from section or disease of the fifth
pair ; the former occurring almost instantaneously, without arrest-
ment of the usual secretion, and apparently from some direct effect
upon the blood-vessels or their contents; the latter coming on
more slowly, and apparently arising, as has been ingeniously sug-
gested, from the arrestments of the usual secretions which protect
the conjunctiva from the irritating effects of the external atmosphere,
as seen in various cases when the nerves of secreting surfaces are
cut.§
Pharyngeal branches of par vagum. — In the human species
we not unfrequently find two pharyngeal branches of the par
vagum, the lower and smaller of which, as Wrisberg describes, is
composed of a filament of the par vagum,, conjoined with others
from the sympathetic. In the dog, (upon which the following
experiments were made,) there is only one pharyngeal branch of
ihe par vagum, on each side as far as I have observed, and this is
composed, as in the human species, of a twig from the internal
* Philos. Transact. 1795, Part 1st, or Medical Tracts and Observations, Vol.
vii. p. 136.
t Journal de Medecine, Chirurgie, &c. December 1816, Tome xxxvii. p. 340.
X Fonctions du Systeme Nerveux Ganglionaire, Chap. ix. 1830.
§ Alison's Outlines of Physiology, p. 148.
28 REID ON THE EIGHTH PAIR OF NERVES.
branch of the fpinal accessory, united with another twig from the
par vagum.
These branches of ihepar vagum have not, as far as I am aware,
been previously made the subject of experimental investigation, so
that their exact functions have hitherto only been a matter of
conjecture.
Is the pharyngeal branch of the par vagum both a motor and sen-
sitive nerve ? We have adduced sufficient evidence when detailing
the experiments upon the glosso-pharyngeal to prove that this is a
motor nerve, for in-repeated experiments made uponanimals immedi-
ately after death, its mechanical and chemical irritation produced dis-
tinct convulsive movements of the muscles in which it is ramified. It
is also there stated that the movements seen on irritating this nerve
immediately after death are generally very vigorous, and embrace
not only the constrictors of the pharynx and siylo-pharyngeus, but
also the muscles of the soft palate. These facts are of themselves
sufficient to entitle us to conclude that this is a motor nerve of these
muscles ; and if we are correct in inferring that the glosso-pharyn-
geal is entirely a nerve of sensation, we may proceed still farther in
our inductions, and affirm that this is the principal, if not the sole
motor nerve of these parts.* In experimenting upon this nerve in
the living animal, it is best exposed in the manner described for
displaying the glosso-pharyngeal. I find that I have notes of ob-
servations made upon the effects of pricking, cutting, and tying
these nerves in seven dogs. In four of these it is expressly stated
that there were not the slightest indications of suffering ; in two,
that there were no decided indications of suffering ; and that in one
there was undoubted evidence of suffering, when these nerves were
irritated in the manner mentioned. In all the seven animals, with
the exception of the last, the difference between the results of pinch-
ing this nerve and the glosso-pharyngeal were very marked. It is
quite possible that if this animal, instead of being kept alive for fur-
ther observation, had been killed at the time, and the nerves care-
fully dissected, some unusual arrangements of the nervous twigs
might have accounted for this difference ; for in the other six the
nerves were as I have stated, pricked, cut, and tied, and yet no
decided evidence of the excitation of pain showed itself I also dis-
tinctly remember, though I have made no mention of it in my notes
taken at the time, that we pricked the trunk of this nerve, or its
large descending branch in some cases, where these were exposed
in experimenting on the glosso-pharyngeal, without causing pain.
When we add to all this the smallness of the nerve, compared with
the extent of the muscles moved by it, we are led to believe that
the sensitive filaments contained in this nerve must be very few, if,
* It is perhaps going' too far to say, that it is the sole motor nerve of these parts ;
for Paletta, in describing- the smaller portion of the fifth pair, states that a twig
from the external pterygoid branch passes to the circumjlexus palati muscle.
Ludwig. Scrip. Nov, Min. Se. Tom. iii. p. 74. Mayo also mentions this twig.
(No. ii. Anat. and Physiol. Comment.)
PNEUMOGASTRIC NERVE. 29
under ordinary circumstances, there are any present at all. I may
state, that, in one of the animals, in which the constrictors of the
pharynx were more freely exposed than usual in operating on the
living animal, vigorous contractions were observed in these muscles,
when the nerve was pricked with the forceps. I need not state,
that to insure accuracy in such experiments, ^are must be taken that
they be made upon the pharyngeal branch of the par vagum, before
it has received any communicating filament (if such be present) from
theglosso-pharyngeal,and that the descending filaments of the glosso-
pharyngeal, which cross this nerve, be excluded.
Effects of section of the pharyngeal branch of the par vagum
upon the function of deglutition. — If this nerve be, as we have
supposed, the motor nerve of the muscles of the pharynx and isthmus
of the fauces, the section of it ought to be followed by considerable
derangement of this function. To test this opinion, the pharyngeal
branch of the par vagum wag cut across on both sides, and a portion
of it removed in five dogs. On three of these, satisfactory observa-
tions were made. Jn all the three, the function of deglutition was
considerably impaired, and this was manifested exactly in the same
manner. I shall only briefly detail one of these experiments.
Exp. XVII. — The pharyngeal branch of the joar vagum. was
cut on both sides before it had given off any branches. The inflam-
mation and swelling of the neck were allowed to subside before any
observations were noted down. This animal, on swallowing a mor-
sel of moderate size, could convey it readily into the posterior part
of the mouth ; but at this stage of the process of deglutition it began
to make strong movements of the muscles of the neck ; during each
of these the head was carried down towards the thorax. After a
greater or less number of these efforts, the animal again looked out
for a fresh portion of food. When the morsel was very small, one
or two of these movements were generally sufficient to pass it through
i\\Q pharynx ; if large, the movements became more violent, numer-
ous, and prolonged.
It appears, then, that when these, pharyngealhrs.uches of the par
vagum are divided, and the pharyngeal and palatine muscles
paralysed, the food is forced through the pharynx to the commence-
ment of the oesophagus, by the powerful contraction of the muscles
of the tongue, and those attached to the larynx and hyoid bone, all
of which are moved, except the digastric and stylo-hyoid muscles
by the hypoglossal and descending branches of the cervical plexus
of nerves. When the morsel is small, the movements of these
muscles seem to force it pretty readily (as can be easily imagined)
through the bag of the pharynx, to the upper part of the cesophagus
when drawn forwards and dilated by the ascent of the hyoid bone.
The difficulty must obviously increase as the size of the morsel
increases ; and the most violent efforts of the muscles which move
the hyoid bone and larynx are necessary, if they succeed at all, in
forcing a large mass through \he pharynx.
While, then, the glosso-pharyngeal is one of the nerves upon
m, 4
30 EEID ON THE EIGHTH PAIR OF NERVES.
which the sensations of the pharynx and fauces depend, the pharyn-
geal nerve of the par vagum is a motor nerve of the same parts.
This view of the functions of these nerves is supported by their
ultimate distribution upon the pharynx and fauces, as far as I have
been able to trace it. From the free anastomoses of the filaments
of the glosso-pharyngeal, pharyngeal branches of the j!?«r ?;a^ww*
and the sympathetic, forming what is properly called \hQ pharyn-
geal plexus, it is absolutely impossible to trace all, or even the
greater part of these filaments to their ultimate distribution, unmixed
with each other. But, from several minute dissections of these
nerves on the human subject, and also upon the dog, where the
ramifications of these nerves are fewer and larger, and do not appear
to anastomose so frequently as in the human species, I have satisfied
myself that those filaments of the pharyngeal branch of the par
vagum, which do not anastomose with others from the glosso-pha-
ryngeal, are entirely ramified in the muscular fibre ; while on trac-
ing the unmixed filaments of the glosso-pharyngeal, they generally,
after a long and winding course through the muscular fibres, pass
ultimately to the mucous membrane, so that comparatively very
few of these are lost in the muscular fibres.
That a few of the filaments of the glosso-pharyngeal appear to be
lost in the muscular fibre, is certainly no proof that this is partly a
motor nerve ; for as it has been shown by Sir C. Bell, and the fact
is easily verified, the muscular fibres belonging to the animal func-
tions (and the palatine and pharyngeal muscles are as it were on the
debatable ground between the animal and organic functions,) are
supplied with sensitive as well as with motor filaments, to endow
them with the muscular sense. If these attempts to unravel the
functions of the most important of the complicated nerves of the
pharynx and fauces, and to ascertain their relative shares in the per-
formance of the function of deglutition, be still imperfect, I may be
excused on account of the intricacy of the subject, and particularly
when it has been stated on the best authority, that up to this period,
"the precise office of each nerve in these parts has not been
ascertained.'^*
Laryngeal Branches of Par Vagum. — Before proceeding to
the consideration of the experiments upon the laryngeal branches
of the par vagum, we shall advert for a little to their anatomical
distribution upon the larynx, since this bears in a direct manner
upon some of the most important questions connected with the
functions of these nerves.
After it had been demonstrated by the experiments of Legallois,
that compression or section of the inferior laryngeal nerves, or of
the trunks of the jo?2ewmo^a5^r/c5,above the origin of these branches,
arrested the movements of the muscles of the glottis, and were fre-
quently followed by dyspnoea, and even by suffocation, particularly
in young animals ; and when it had also been ascertained by the
observations of physicians, that derangement of the movements of
* Alison's Outlines of Physiology, p. 213.
PNEUMOGASTRIC NERVE. 31
these muscles is also not unfrequently the cause of alarming parox-
ysms of dyspnoea, more especially in children, occasionally termi-
nating in death, it became an object of considerable practical impor-
tance to ascertain the relative share which these nerves have in
regulating the movements by which the aperture of the glottis is
diminished or enlarged. For without a correct knowledge of the
manner in which these movements are produced in the healthy state,
it is apparent, that we cannot with safety advance one step in the
explanation of their deranged conditions.
There are obviously two methods of examining this question, viz.
by tracing these nerves to their ultimate distribution, and by experi-
ments on animals. If in following the first method, we find that
one of these nerves is distributed upon certain muscles of the larynx,
and not upon others, we must of course consider it as finally ascer-
tained that this nerve has no effect, in regulating, as a motor nerve,
the movements of those muscles, upon which it is not distributed.
And, as is well known, the anatomical arrangement of these-nerves
is the strongest fact adduced by Magendie in favour of his opinion,
that the superior laryngeals move the muscles which shut the
superior aperture of the glottis, and the inferior laryngeals or
recurrents those which open it. For according to Magendie,*
Cloquetjt and many other anatomists and physiologists who have
taken it on their authority, the arytenoid muscles receive their
nervous filaments solely from the superior laryngeals. That
filaments of the superior laryngeal nerves pass into the arytenoid
muscles is allowed by all anatomists ; but there can be as little
doubt that they receive a filament from each of the inferior laryn-
geals. Amongthosewho have described this ary/ewozflf branchof the
inferior laryngeal or recurrent previous to the announcement of this
statement by Magendie, we may mention Andersch,t Bichat,§ and J.
P. Meckel. II And, among those who have since that time examined
these nerves, and ascertained the existence of this arytenoid branch,
we may mention Rudolphi,ir Bischoff',** Swan,tt and Cruveilhier.tJ
I have repeatedly satisfied myself of the existence of this arytenoid
branch of the inferior laryngeal, and the dissection is one which
can leave no kind of doubt on the matter. It is obvious that those
who have failed in detecting this branch have been misled by the
circumstance, that it appears to enter the crico-arytenoideus posti-
cus, and to be destined for that muscle. On being traced upwards,
* Compendium of Physiology, 4th edit. p. 132. Milligan's Translation.
f Traite d'Anatomie Descriptive, Tome ii. p. 622.
X Fragmentura Descr. Nerv. Card. &c. in Tom. ii. p. 139. Ludwig, Scrip.
Nerv. Min. Sel.
§ Traite D'Anatomie Descriptive, Tome iii. p. 216.
II Manuel D'Anatomie Gen. Deserip., &c. Tome iii. p. 66.
Tf Physioiogie. Bd. ii. p. 374. These dissections were made by Schlemm,
** Comment. De Nervi Accessorii Willisii Anat. et Physiol, p. 27. 1832.
ft A Demonstratioa of the Nerves of the Human Body. Plate xvi. fig. vii. This
contains a very accurate representation of the course of this twig.
%X Anatomie Descriptive, Tome iv. p. 963. 1835. Dr. Sharpey informs me
that he has been accustomed to describe this branch ia his lectures.
32 REID ON THE EIGHTH PAIR OF NERVES.
however, it is found to continue its course inwards and upwards,
between the anterior surface of the crico-arytenoideus posticus,
and the posterior surface of the cricoid cartilage, to reach the
lower margin of the arytenoid muscles. I shall shortly state the
conclusions I have come to regarding the ultimate distribution of
these nerves upon the larynx and upper part of the trachea, drawn
from careful dissections in the human subject. The recurrent in
its course upwards to the larynx sends various filaments to the
muscular fibres which complete the tube of the trachea behind, and
others which perforate the narrow intervals between the cartilages
to reach the mucous membrane of the trachea. Having arrived at
the larynx, it sends distinct branches to the crico-arytenoideus
posticus, crico-arytenoideus lateralis, thyro-arytenoideus and
arytenoid muscles, or, in other words, to all the muscles which
move the arytenoid cartilages.* These branches evidently termi-
nate in the muscular fibre. In fact, the only filaments of the infe-
rior laryngeal which appear to proceed to the mucous surface of
the larynx, are a ^qw from the terminating or thyro-arytenoid
branch. I have seen one or two very slender filaments pass to the
crico-thyroid, from that branch of the inferior laryngeal, which,
after sending ramifications to the mucous surface of the lower part
of the pharynx, anastomoses with the external laryngeal branch
of the superior laryngeal, but these filaments do not appear to be
constant.
Superior Laryngeal Nerve. — The external laryngeal branch
of the superior laryngeal nevve, gives a few filaments to the inferior
constrictor of the pharynx, more to the thyro-hyoid muscle, and
a comparatively large and distinct branch to the crico-thyroid, which
evidently terminates in that muscle. The internal laryngeal branch
of the same nerve is almost entirely distributed upon the mucous
surface of the epiglottis and interior of the larynx. By far the
greater part of the filaments of this branch of the nerve which ramify
in the arytenoid, thyro-arytenoid, and crico-arytenoideus latera-
lis muscles proceed to the mucous surface, and generally after a
long and winding course among the muscular fibres. They thus
present a striking contrast to the abrupt manner in which the fila-
ments of the crico-thyroid twig of the external laryngeal terminate
in the muscular fibre. In fact, the only filaments of this internal
branch of the superior laryngeal \w\\\ch. appear to terminate in
the muscular fibre, are some of those which pass into the arytenoid
muscles. Those filaments which seem to terminate in the arytenoid
are part of a twig which anastomoses with the arytenoid branch of
the inferior laryngeal in the substance of the arytenoid muscle. A
knowledge of the distribution of these nerves is, however, of itself
insufficient to clear up their functions in a satisfactory manner, for
it must be obvious that, though by anatomical investigation, We
may ascertain that certain nerves supply particular muscles, and in
* I here consider the muscular fibres described as the thyro-epiglottideus as a
part of the thyro-arytenoideus.
PNEUMOGASTRIC NERVE. 33
this manner frequently form a pretty accurate notion of their func-
tion, yet when nervous filaments come from more than one source,
and from a complex nerve like the par vagum, it is only by experi-
ments upon animals, or by the observation of disease, that we can
hope to ascertain which are motor, and which are sensitive. Besides
the free anastomoses between those nerves must render it doubtful
from which of them some of the minute filaments come.*
In entering upon the physiological investigation of the functions
of the laryngeal nerves, I first proceeded to examine what eflect
the irritation of these has upon the muscles of the larynx in a
recently killed animal.
Exp. XVIII. — The larynx was exposed and the glottis brought
into view in a dog, immediately after it had been killed by a dose
of prussic acid. On applying the galvanic wires to each recurrent
nerve alternately, violent movements of the muscles of the larynx
followed, and the arytenoid cartilages were first seen to approach
each other, and then to recede. At each movement the small
cartilages at the summit of the arytenoids (cornicula laryngis)
<;ame into close contact. On galvanising the superior laryngeal
nerves, or rather the internal branches of these, for they had been
cut across a little above where they perforate the thyro-hyoid liga-
ment, no movement was observed. On again applying the wires
to the recurrents, or to the trunk of the par vagum above the
origin of the recurrent, the same results were obtained as before.
The movements which followed irritation of the trunk of the^jar
vagum were not so strong as those from irritation of the recurrent
itself. Dr. Alison was present at this experiment.
Exp. XIX. — The larynx was exposed, as in the preceding
experiment, in a dog bled to death from the femoral arteries, but
without dividing the superior laryngeal nerves. On applying the
galvanic wires to the superior laryngeals before they had given
off" the external laryngeal branch, strong convulsive movements
of the crico-thyroid muscle followed, by which the cricoid carti-
lage was approximated to and drawn under the thyroid, and the
larynx shortened. All the muscles attached to the arytenoid
cartilages remained perfectly quiescent, so that no change took
place upon the superior aperture of ihe glottis. On applying the
wires to the recurrent nerves alternately, the same vigorous move-
ments of the arytenoid czviWdi^Q?, were observed as in the preceding
experiment. It was remarked that when the galvanic wires were
kept applied to one of these recurrent nerves for some short time,
the arytenoid cartilages were so approximated as to shut com-
pletely the superior aperture of the glottis. On removing one of
the wires the cartilages then separated.
These experiments were repeated on five other animals with the
same results. In two of these, the movements observed on irritating
* For some farther remarks upon the anatomy of these laryngeal nerves, see
Part III.
4
34 REID ON THE EIGHTH PAIR OF NERVES.
the nerves were much feebler than those described, but, though
varying in degree, as might be expected, they never varied in kind.
I may add, that these movements are also well marked when the
nerves are pinched with the forceps, and after they have been
detached from the trunk of the pa?' vagum. In these experiments
it was distinctly observed, that the only outward movements of the
arytenoid cartilages, seen on irritating the recurrents, were merely
occasioned by their return to their former position after they had
been carried inwards. This outward movement, then, no doubt,
entirely depended upon the elasticity of the parts.*
From these experiments it was concluded that all the muscles
which move the arytenoid cartilages receive their motor filaments
from the inferior laryngeal or recurrent nerves. And as the
force of the muscles which shut the glottis preponderates over that
of those which dilate it, so the arytenoid cartilages are carried
inwards when all the filaments of one or both of these nerves are
irritated. These experiments also show us, that one only of the
intrinsic muscles of the larynx receives its motor filaments from the
superior laryngeal, viz. the crico-thyroid muscle, and that, conse-
quently, the only change which this nerve can produce on the
larynx, as a motor nerve, is that of approximating the cricoid to
the thyroid cartilage, — in other words, of shortening the larynx.
I find that Bischofft had examined the effect of irritating these
nerves in the recently killed animal. And though he failed to
observe, the contraction of the crico-thyroid muscle, and the con-
sequent shortening of the larynx^ produced by irritation of the
superior laryngeal nerve, and in place of this describes some
supposed palpitation of the mucous membrane of the larynx, yet
the other results obtained by him were similar to those we have
described in Exp. XIX.
We have now to see how far the views we have stated above, are
supported by the subsequent experiments on living animals.
The superior laryngeal nerve was cut on both sides in two
dogs and one rabbit, and the animals readily swallowed both solids
and fluids without exciting the slightest cough or the least difficulty
of breathing. The lungs were carefull)'' examined after death,
and none of the food taken could be detected in the air-passages.
In several animals the superior laryngeals were first cut, and the
inferior laryngeals immediately afterwards, and it was ascertained
that the previous division of the superior laryngeals did not
prevent the difficult breathing and symptoms of suffocation, which
* In ttiese experiments I never could perceive any contractions of the iJiyro-
hyoid muscle and inferior conslrictor of the pharynx, on irritating the superior
laryngeal, even when the crico-tkyroid was acting most vigorously. Neither
could I ever observe any movements of the crico-thyroid on irritating the recur-
rent. The thyro-hyoid muscle receives its motor filaments from the hypoglossal
and the inferior constrictor of the pharynx from the pharyngeal branch of the par
vagum,
f Oper. cit. p. 27.
PNEUMOGASTRIC NERVE. 35
not unfrequently follow the division of the inferior laryngeal
nerves, particularly in young animals. To procure still more
positive assurance of the effect of section of the different laryngeal
nerves upon the movements of the muscles attached to the aryte-
noid cartilages, the following experiments were performed.
Exp. XX. — All the four laryngeal nerves were exposed in a
full-grown cat. The larynx was then dissected out by cutting
between the hyoid bone, and thyroid cartilage, and drawn forwards
so as to expose the glottis without disturbing the nerves. When
the glottis came into view, the arytenoid cartilages were observed
to be drawn backwards and outwards during inspiration, and to
approximate considerably during expiration. The extent of these
movements of the muscles of the glottis was in proportion to the
extent of the other respiratory movements. When the animal was
quiet and breathing less forcibly, the movements were slight.
While uttering a cry, the sides of the superior aperture of the
glottis were closely approximated, and were thrown into vibratory
motion. While struggling violently, the superior aperture of the
glottis appeared completely closed. A small opening was made
into the trachea, and a silver probe passed upwards. This appeared
to excite little if any uneasiness, until it arrived at the larynx. As
soon as it entered the larynx it was instantly followed by close
approximation of the sides of the superior aperture of the glottis,
violent cough, and evident uneasiness. The same effect was pro-
duced by introducing the probe from above. After satisfying
myself of these facts, one of the recurrent nerves was first cut
across, with the effect of evidently diminishing the movements of
the arytenoid cartilage on the side cut. The other recurrent was
then divided, and instantly all the movements of the muscles of the
glottis ceased, and the arytenoid cartilages were never carried
outwards beyond the position in which they are found after death.
The superior laryngeals were then cut, without effecting the
slightest enlargement or anj"" other change upon the glottis. As
the arytenoid cartilages, after section of the inferior laryngeal
nerves were now mechanically carried inwards by the rushing of
the air through the diminished aperture of the glottis, during each
violent inspiration of the animal, by which the aperture was still
further contracted, its edges were kept apart with the forceps, until
an opening was made in the trachea to prevent the immediate
suffocation of the animal.* The experiment being now completed,
the animal was killed by a dose of prussic acid.
Exp. XXI. — The larynx was brought into view in another full-
grown ca.t, as in the preceding experiment, and the various move-
ments of the muscles of the glottis again watched for a short time.
The superior laryngeal nerves were then cut without diminishing
in the least any of the movements of the arytenoid cartilages.
* It is important to remark, that section of the superior larj'ngeals did not
arrest these inward movements of the arytenoid cartilages.
36 REID ON THE EIGHTH PAIR OF NERVES.
The sides of the superior aperture of the glottis were approximated
in crying, so as to form but a narrow fissure, and in struggling, the
aperture became completely closed, as when the superior laryngeal
nerves were uninjured.
Nothing could be more satisfactory than the results of these two
last experiments, and they complete the accumulated facts which
we have adduced, in fully disproving the statement of Magendie, to
which we have already referred, viz. that the inferoir laryngeal
supplies those muscles only which enlarge the aperture of the
glottis, while the superior laryngeal furnishes the motor filaments
to those muscles which shut the glottis* They also illustrate in
a very satisfactory manner the cause of the dyspncea in some cases
where the inferior laryngeal nerves are cut, compressed, or
irritated. To the consideration of this last point we shall after-
wards return. The movements of the muscular fibres of the
trachea, no doubt, depend upon the recurrent, but we had no
opportunity of actually witnessing this. If it were thought neces-
sary to adduce any additional evidence, that the muscles of the glottis
can act involuntarily, like the other muscles of respiration, we
might state that we have seen these movements going on in unison
with those of the other respiratory muscles, in animals deprived of
all volition by a fatal dose of prussic acid.
We have now to examine to what extent these nerves are con-
nected w'\i\i sensation. And, first, with regard to the effect of irri-
tating the trunks of these nerves. I have exposed the superior
laryngeal nerves repeat-edly in living animals, and in all, as I have
already stated, decided indications of suffering presented themselves,
* Allowing even that the recurrent nerves gave no filaments to the arytenoid
muscles, the proposition of Magendie, that the superior laryngeal nerve alone
moves those muscles wh'ch shut the glottis, would not necessarily be correct.
For it is universally admitted, that filaments of the recurrent nerve are distributed
in the thyro-arytenoid muscle, and no attempt has been made to prove these
filaments to be merely sensitive ; on the other hand, we have seen, from the
anatomical distribution of these nerves, that this muscle must receive its motor
filaments from the recurrent. Now, an examination of the course of the fibres
of this muscle will, we think, fully bear out the generally received notion of its
action, viz. that it must assist in diminishing the aperture of the glottis. The
authority of Hoffman, (Aeroteria, p. 91, as quoted by Haller,) and of Haller
himself, (Element. Physiol. Tom. iii. p. 387, Laus. 1761,) may doubtless be
adduced in support of the opinion, that it enlarges the glottis. We consider,
however, this view of the action of the muscle untenable. In confirmation of the
opinion, that the action of this muscle has a contrary effect, and assists in dimin-
ishing the glottis, we may quote the authority of Cowper, Albinus, Soemmerring
(Corporis Hum. Fabrica, Tom. ii. p. 138, 1794;) Meckel (Oper. cit. Tom. iii.
p. 497,) and Lauth (Mem. de I'Acad. Roy. de Medec. Tom. iv. p. 110, 1835.)
Some authors, as Meckel, Lauth, and Cruveilhier (Oper. cit. Tom. ii. p. 669,)
even maintain that the action of the crico-arytenoidei laterales muscles, is to
diminish the aperture of the glottis. Bichat also asserts, (Anat. Descrip. Tom.
ii. p. 407,) that "les crico-arytenoidiens posterieurs sont les seuls agens de la
dilatation de la glotte." The action of these crico-arytenoidei laterales muscles
is certainly difficult to determine, as it must depend in a great measure upon the
position of the arytenoid cartilages at the lime they are thrown into action, and
the synchronous contraction of other muscles.
PNEUMOGASTRIC NERVE. 37
except in two dogs which had previously endured protracted pain.
In some of these dogs, distinct convulsive movements of the muscles
of the throat and lower part of the face were observed, similar to,
but less strongly marked than those accompanying irritation of the
glosso-pharyngeal. Whether this movement depended upon the
sudden excitation of pain, or of some specific sensation, similar to,
though feebler than that which we suppose to attend irritation of the
glosso-pharyngeal nerve, we cannot pretend to determine. In sup-
port, however, of this last supposition, we may urge the anatomical
fact, that a considerable number of the filaments of this nerve are
distributed upon the mucous surfa-ce of ihe pharynx. I was anxious
to ascertain whether irritation of these nerves would produce closure
of the glottis by a reflex action. As the experiment is one in which
it is difficult to arrive at accurate conclusions, without inflicting much
pain, I did not persevere in the attempt. I may state, however, that
in Exp. XXI. we observed, that when each of the superior laryngeal
nerves was cut, the glottis was suddenly closed ; but whether this
was occasioned by a struggle of the animal from the excitation of pain,
or depended upon the muscles of the glottis being thrown into con-
traction by a reflex action, I cannot venture to decide. Irritation
of the recurrent nerves is attended by much feebler indications of
sufiering. That this nerve does, however, contain some sensitive
filaments^ is indicated not only by the circumstance, that when
pinched or tied, the animal generally gives symptoms of feeling pain,
but also from the fact, that it sends numerous filaments to the mucous
surface of the trachea, a few to the mucous surface of the lower part
of the pharynx, and even a fewto the inner surface of the larynx.^
With regard to the effects of section of these nerves upon the sensi-
bility of the mucous surface of the larynx, we have obtained very
satisfactory results. We might h priori determine from the anato-
mical distribution of these nerves, that the sensations referred to the
larnyx are almost entirely dependent upon the superior laryngeal
nerves. In Exp. XX. we observed that irritation of the mucous
surface of the larynx after section of the inferior laryngeals, was
still followed by great uneasiness and efibrts to cough, while the
movements of all the muscles of the glottis were arrested. In Exp.
XXI. on the other hand, no uneasiness, or efforts to cough were ex-
cited even by rubbing the probe against the inner surface of the larynx,
after section of the superior laryngeals, while the sympathetic and
voluntary movements of the muscles of the glottis went on as before.
I have also had occasion, while performing other experiments, to verify
the same facts in the manner followed by Magendie in one of his lec-
tures at the College de France. t Through an opening made into
the trachea, a probe was passed upwards to the larynx. This excited
little or no uneasiness until it reached the larynx. As soon as it
entered the larynx, it excited great uneasiness and violent paroxysms
* We shall afterwards have occasion to examine the functions of the oesophageal
filaments of the recurrent,
t Lancet, July 1, 1837.
38 REID ON THE EIGHTH PAIR OF NERVES.
of coughing. Section of the recurrents had no effect in dinninishing
the severity of these paroxysms of coughing, while Ihey were in-
stantly arrested by cutting across the superior laryngeals. Whether
this striking difference between the sensibility of the parts supplied
by the two laryngeal nerves depends upon the number of these fila-
ments, and the manner in which they are distributed, or upon some
difference in their endowments, I cannot pretend to decide.
In Exp. XX. we observed that when the superior laryngeals
were divided, the presence of the probe in the interior of the larynx
was not only unattended by uneasiness and cough, but it also no
longer occasioned any sudden closure of the superior aperture of
the glottis; and in Exp. XXI. though each introduction of the
probe occasioned great uneasiness and efforts to cough after section
of the recurrents, still the muscles of the glottis were not thrown
into spasmodic contractions, as when they were entire. From these
experiments we perceive, that when either the recurrents or supe-
rior laryngeals are divided, so as to break the nervous circle which
these form through their connection with the central organs of the
nervous system, irritation of the mucous surface of the larynx no
longer excites contraction of the surrounding muscles, though their
contractility has not been impaired. This nervous circle we may
suppose to begin at the mucous surface of the larynx, to pass upwards
through the filaments of the swperior laryngeals to the medulla ob-
longata, and back again to the muscles through the filaments of the
recurrent. I have also repeatedly attempted, but in vain, to excite
contractions of the muscles of the glottis, by irritating the mucous
surface in an animal recently killed. From these facts, we think
that we are justified in concluding, that when any irritation is
applied to the inner surface of the larynx in the healthy state
of the parts, this does not excite the contraction of the muscles
attached to the arytenoid cartilages by acting directly upon them
through the mucous membrane, but that this contraction takes place
by a reflex action, in the performance of which the superior laryn-
geal is the sensitive, and the inferior laryngeal is the motor nerve.
And when we remember that no appreciable interval of time inter-
venes, between the application of an irritant to the mucous surface
of the glottis and the contraction of its closing muscles, and reflect
upon the circuitous course through which the nervous influence must
travel, before it reaches these muscles to stimulate them to contrac-
tion, we may form some faint idea of the astonishing rapidity with
which changes are accomplished in the nervous system. We also
ascertain from these experiments that in the small recurrent nerves
two sets of motor filaments are included, — one set transmitting the
nervous influence which stimulates the opening muscles of the
glottis to act synchronously with the other muscles of inspiration,
the other set transmitting the nervous influence which stimulates
the closing muscles to act synchronously with the other muscles
of expiration. And when we remember that these filaments arise
near each other, and from the same medullary tract of the spinal
chord, this would furnish us with an additional proof (if any more
PNBUMOGASTRIC NERVE. 39
were necessary) of the futility of attempting to explain sympathetic
or associated actions by mere nervous connections.
From all these experiments, then, upon the laryngeal nerves, we
are inclined to draw the following conclusions :
1. That the superior laryngeal furnishes one muscle only with
motor filaments, viz. the crico-thyi^oid.
2. That the superior laryngeal furnishes all, or at least nearly all,
the sensitive filaments of the larynx, and also some of those dis-
tributed upon the mucous surface of the pharynx.
3. That the inferior laryngeal or recurrent furnishes the sensitive
filaments to the upper part of the trachea, a few to the mucous
surface of the pharynx, and still fewer to the mucous surface of
the larynx.
4. That when any irritation is applied to the mucous membrane
of the larynx in the healthy state, this does not excite the contraction
of the muscles which move the arytenoid cartilages by acting
directly upon these through the mucous membrane, but that this
contraction takes place by a reflex action, in the performance of
which the superior laryngeal is the sensitive, a.n6. the inferior laryn-
geal is the motor nerve.*
Does Section of the Laryngeal Nerves prevent the ingress of
the food into the Larynx during Deglutition ? — All the four
laryngeal nerves were divided in two dogs, and four rabbits. Both
dogs and two of the rabbits swallowed solids and fluids readily, and
without exciting cough or difficulty of breathing. The other two
rabbits refused the milk, but they swallowed solids without inconve-
nience. All these animals were carefully examined after death, and
not the slightest trace of the food could be detected in the air-pas-
sages. From these experiments it would appear that if the closing
muscles of the glottis can, as Magendie has shown, prevent the
entrance of food into the larynx after removal of the epiglottis,
the epiglottis can, on the other hand, prevent the ingress of food
into the larynx, when the movements of all the muscles which
diminish the size of the glottis have been suspended by section of
the laryngeal nerves.
Effects of Section of the Laryngeal Nerves upon the Voice. —
In the experiments upon the two dogs mentioned above, and others
which we might adduce, in which the superior laryngeal nerves
were cut, I could detect no change upon the voice. I will not by
any means maintain that no change was effected, for my perception
of differences in sound is far from being good. Since the variations
ih the length of a tube alter the graveness and acuteness of the sounds
which it emits, we would expect that section oi ihe. superior laryn-
geal should, by arresting the movements of the crico-thyroid mus-
cles, produce some change in this respect. Magendiet mentions that
an animal, after section of the superior laryngeal nerves, " loses
* The functions of the oesophageal filaments of the recurrent will be examined
along with the other oesophageal filaments of the par vagum.
t Oper. cit. p. 138.
40 REID ON THE EIGHTH PAIR OF NERVES.
almost all its acute sounds; it acquires besides a constant gravity,
which it had not previously." This he attributes to the arrestment
of the movements of the arytenoid muscles. But we have shown
that section of these nerves has no such effect. Supposing Magendie
quite correct* in the occurrence of this change of the voice, may it
not be explained in this manner. He himself states,t that during
acute sounds, the vocal tube is shortened, and lengthened during the
formation of those which are grave. Now section of the superior
laryngeals would necessarily have the effect of preventing the tube
from being so much shortened as during the natural action of the
parts ; in other words, it might prevent the production of the acute
sounds ; and may not the relaxed state of the crico-thyroid mus-
cles be one of the conditions necessary for the production of a grave
sound.
With regard to the effects of section of the recurrent upon the
voice, — a physiological experiment which has been performed so
very frequently since the time of Galen, we have no observations
to make. We may merely remark, that we found, as the second
MonroJ has stated, that the voice is not altogether lost, for we ascer-
tained that the animal, in some cases at least, could still emit a very
faint howl.
It is not my object here to examine the various combined con-
tractions of the muscles of the larynx, which these laryngeal nerves
effect, — whether instinctively or sympathetically, as in natural or in-
articulate language, and in the function of respiration ; or voluntari-
ly, as in artificial or articulate language. Of the great disturbance
of these important functions, which either necessarily or occasionally
arises from section of these nerves, we have had abundant proof.
Perhaps the most interesting of all the associated movements of these
muscles to the practical physician, are those connected with the
respiratory function, as they promise to throw light upon some
important forms of disease. Since these movements were first
pointed out by Legal]ois,§ they have been repeatedly observed in
the lower animals by several experimenters ; and by Mr. Mayo||
and Sir C. Bell,'!r in individuals of the human species, after unsuc-
cessful attempts at suicide. The energy and extent of these move-
ments, when the respiration is much hurried by the struggles and
pain of the animal, appear quite astonishing when witnessed for the
first time. When the respiration, however, is such as is natural in
a state of rest, the sides of the glottis remain quiescent, or at least
nearly so.** The manner in which section or compression of the
* BischofF (Oper. cit. p. 27.) says " duobus canibus laryngeum superim-em
utrimquedissecui; sed neutrius canis vox nee post plures quidem dies mutata
est."
f Oper. cit. p. 139. % Observations on the Nervous System, p. 65.
§ Sur le Principe de la Vie, p. 197. || Medical Gazette, Vol. xiv. p. 22.
•fT Nervous System, p. 484, ed. 3. or Phil. Trans. 1832.
** Legalloisand Mayo, oper. cit. Itisprobable that when the larynx is small,
as in young animals, these movements are constant, even when the respiration is
not hurried.
PNEUMOGASTRIC NERVE. 41
laryngeal nerves arrests these movements is well illustrated by Exp.
XX. and XXI. From these we learn, that when the inferior laryn-
geal nerves are cut, all the movements of the muscles of the aryte-
noid cartilages are arrested, and the superior aperture of the glottis
can no longer be dilated during inspiration. In fact, the sides of
the glottis are not only no longer separated by an active force, but
they are rendered quite passive, and yield readily, within certain
limits, to the slightest external force applied to them. Th.Q glottis
now presents the appearance which it does some time after death ;
indeed it is probably still more diminished in size, for as the con-
tractility of the muscular fibre is unimpaired by section of the nerves,
their tonicity may still occasion further diminution, since the strength
of the closing, preponderates over that of the opening muscles.
When the recurrent nerves are cut in an adult animal, where the
aperture of the larynx is large, a quantity of air may still find its
way through the diminished aperture of the ^/o^//^, adequate in many
cases to carry on the respiratory process in a sufficient manner, par-
ticularly if the muscles of inspiration are not acting violently. If,
on the other hand, the capacity of the larynx is proportionally
smaller, as in young animals, the air rushes through the diminished
aperture in a narrower stream and with increased force, more espe-
cially when the insjiiratory movements are violent, — or, in other
words, when the capacity of the thorax is suddenly and greatly
enlarged, — and the consequence is, that an insufficient quantity of
air reaches the lungs. This quantity is still further reduced, by the
circumstance, that the now passive sides of the superior aperture of
the glottis are carried inwards by the current of air, as in Exp. XX.
where it was remarked that, at each inspiration the arytenoid car-
tilages were so closely approximated, as almost entirely to prevent
the ingress of air, and where it was necessary to hold aside the edges
of the superior aperture of the glottis, \o prevent the immediate
suffocation of the animal. It is the inspiration alone of the animal
which is difficult, for the expiration is easy. The arytenoid car-
tilages are readily pushed aside by the expired air. The occur-
rence or non-occurrence of dyspnoea or suffocation after section of
the inferior laryngeals is to be explained by the greater or less
capacity of the larynx in the individual animal, and the violence
of its respiratory movements at the time. The crowing sound
which frequently attends this condition of the laryngeal muscles is
of course a mere physical effect, and depends upon the current of
air rushing rapidly through the diminished aperture of the glottis,
and may be imitated in the larynx of a dead animal. It is evident,
then, that we must again return to Legallois's explanation of the
cause of the dyspnoea after section of the recurrent nerves, which
I have been here illustrating and extending. For though this acute
physiologist does not enter upOn the consideration of the relative
share which these nerves have in the movements of the intrinsic
muscles of the larynx, yet he distinctly attributed the dyspnoea
m 5
42 REID ON THE EIGHTH PAIR OF NERVES.
after the section of the recurrents to muscular paralysis.* He also
explained the manner in which the arytenoid cartilages are carried
inwards by the current of air passing through the glottis, from
■what takes place when a syringe is fixed to the trachea, — detached
with the larynx, — from the body after death, and the air drawn
forcibly downwards. At each stroke of the syringe, the edges of
the superior aperture of the glottis are approximated, and if the
current of air is strong, the aperture is completely sbut.t
Whether the crowing disease of children, or laryngismus stri-
dulus, depends upon the movements of the muscles of the glottis
being suspended by compression of the recurrents or oiihepneu-
7WO^«5/'nc5 themselves above the originof these branches, by enlarged
glands, as the late Dr. Ley supposed, or whether, as is more gener-
ally imagined, it depends upon a spasm of these muscles, and " is
obviously a part of a more general spasmodic aflreetion,"J it is not
for me to determine. From the experiments we have detailed, it
is, however, apparent, that severe dyspnoea amounting to suffocation
may arise both from irritation and compression of the inferior laryn-
geal nerves, or the trunks of the pneumogastrics. For when both
or even one recurrent nerve was irritated, the arytenoid cartilages
were approximated so as in some cases to shut completely the supe-
rior aperture of "Cae glottis ; and we have already explained at some
length how paralysis of this nerve occasioned by compression or any
other cause, should produce this affect by arresting all the move-
ments of the muscles of the glottis. We shall leave it to those
who have had frequent opportunities of seeing this disease, to deter-
mine which of these two causes will best explain the phenomena
which it presents. There appears, however, to be little doubt, that
the crowing respiration and dyspnoea which accompany some cases
of hysteria, depend upon a spasmodic closure of the glottis, pro-
duced by some irritation of the recurrent nerves.
CEsophageal Branches of Par Vagum. — It is obvious that, as
the oesophageal branches of i\\e par vagum cannot be divided
separately, we can only ascertain the functions of these by cutting
the trunk of thejoar vagum itself in the neck.
Effects oj the irritation of these nerves in an animal recently
* " C'est done bien reellement en paralysant les muscles arytenoidiens et en
relachant par la les ligaments de la glotte, que la section des nerfs recurrens
produit la suffocation." Whether Legallois by the term arytenoid muscles
here means the muscles universally known by this name, or whether he errone-
ously extends it to all the muscles attached to the arytenoid cartilages, I have
not been able to ascertain from his writings.
f In performing this experiment, care must be taken to produce a large and
rapid current of air, such as we would suppose to pass through the larynx when
the chest is rapidly and fully dilated in a violent inspiration. If the syringe
employed is one of moderate size, a small larynx must be selected, otherwise
the experiment will fail.
For an excellent exposition of the principal conditions of the system under
which violent inspirations are apt to be made, or, in other words, when the
aperture of the glottis is likely to be most diminished, see Dr. Ley on Laryn-
gismus Stridulus, p. 85.
^ Dr. Marshall Hall's Lectures on the Nervous System, p. 76, 1836.
PNEUMOGASTRIC NERVE. 43
killed. — I have repeatedly seen violent muscular contractions
induced along the whole length of the tube of the oesophagus
by mechanical or chemical irritation of the trunk of the par vagum
in dogs, rabbits, and cats. At each application of the irritant, the
cesophagus became shortened, and diminished in calibre. These
movements extended also to the cardiac extremity of the stomach.
In the stomach they were evidently more slow, prolonged, and
vermicular, than in the oesophagus. They extended somewhat
slowly from the cardiac orifice, over a greater or less extent of the
left portion of the stomach. In one case they were more extensive
and rapid than in the others, but still retained somewhat of their
vermicular appearance. Muscular contractions of the oesophagus
on irritating \\iepar vagum in an animal recently killed, have been
observed by Arnemann,* Cruikshank,t and Mayo.f Mr. Mayo
could not perceive any muscular movements of the stomach upon
irritating this nerve. These were, however, frequently observed
by Tiedemann and L. Gemelin.§ They have also been inferred by
Brechet and Dr. M. Edwards,|| from the effects of galvanising the
lower ends of the cut pneumogastrics in the neck on the living
animal.
Effects of section of the oesophageal branches upon the move-
ments of the oesophagus.
Exp. XXII. — A portion of \hQ par vagum, was removed on both
sides, high in the neck, in a rabbit which had fasted sixteen hours.
The portions removed included the second ganglion of ihe. par
vagum, and consequently the origin of the superior laryngeals.
The respiration continued heaving, and somewhat difficult for a
short time, but it soon became pretty easy. Some parsley was now
thrown down on the opposite side of the room, which it immediately
made for, and began to eat. It appeared to swallow the first mouth-
fuls readily, and without inconvenience. As it continued to eat, its
breathing again became heaving, and it apparently felt very uneasy.
It Vv^as soon after seized with attempts to vomit or cough,1[ and retired
from its food. After a short time the dyspnoea abated somewhat,
and it returned to eat. It had only swallowed a small quantity,
when the uneasiness, dyspnoea, and efforts to vomit, became as
urgent as before. Every time it returned to eat (and it did this
* As quoted by Soemmering, oper. cit. Tom. iv. p. 273.
f Medical Facts and Observations, Tom. vii. p. 153, or Phil. Trans. 1795.
X Mayo, Anatomical and Physiological Commentaries, No. ii. p. 15.
§Recher. Exper. Physiol, et Chem. sur la Digestion, &c. p. 374.
II Archiv. Gen. de Med. Tom. vii.
^It certainly presented much more the appearance of a cough than an effort to
vomit. As, however, apparently similar muscular movements have been described
by late experimenters, as an effort to vomit, and the possibility of the excitation
of the sensation which induces coughing, under such circumstances, has been
strongly denied, I will not at present venture an opinion on this question, until
I have examined it more thoroughly. We shall call it in the meantime an effort
to vomit. We could not expect a perfect cough in an experiment of this kind,
after the movements of the muscles of the glottis had been arrested.
44 KEID ON THE EIGHTH PAIR OF NERVES.
several times) these were always much increased in severity ; so
that it more than once appeared dying from suffocation. The
breathing was now constantly very difficult, with a rattling sound
in the trachea. Five hours after the section of the nerves, it again
approached the parsley, but it had only eaten a very short time, when
it sprung into the air, and after making violent struggles, and appa-
rently suffering great uneasiness for nearly a minute, it died. —
Dissection. This was done immediately after death. The nerves
were found fairly divided. On exposing the trachea in the neck,
I was struck with the great size of the oesophagus, which was dis-
tended like a sausage, and evidently compressed the trachea. The
green colour of the parsley was quite distinctly seen through the
coats of the oesophagus. The. pharynx contained some parsley, but
was by no means filled by it. The oesophagus in the thorax was
distended, in the same manner as in the neck, down to the stomach.
The stomach was well filled, but was certainly far from being
unnaturally distended, aand could have easily held more in its pyloric
extremity. Considerable quantities of the masticated parsley were
found in the larynx, trachea, and bronchi. In some parts of the
lungs it was found in the minutest air-cells, and one or two portions
were perfectly dense, from the quantity which they contained.
Exp. XXIII. — The pneumogaslrics were cut above the origin
of the superior laryngeals in another full grown rabbit, after fast-
ing twenty-four hours. This was followed by pretty severe dyspnoea
and uneasiness. It refused for some time to eat the parsley laid
before it. When it began to eat, it was observed that it swallowed
the first mouthfuls perfectly, and without any additional uneasiness.
As it continued to eat it became restless, and was affected similarly
to the animal in the preceding experiment. The breathing after this
continued very difficult, and it made but very few subsequent attempts
to take food. It was seen alive ten hours after the section of the
nerves. It was found dead next morning. — Dissection. The oeso-
phagus was distended by the parsley, though not to the same extent
as in the preceding experiment. The calibre of the trachea was
also evidently somewhat diminished by the stuffed oesophagus.
The stomach contained a moderate quantity of food, but was by no
means fully distended. A small quantity only of the masticated
Darsley was found in the air-tubes.
We believe that in these two experiments, the first mouthful was
carried into the upper portion of the oesophagus in the usual manner,
but as the muscular movements of this tube had been susi)ended, it
remained there. As additional mouthfuls arrived, they propelled
forwards those which preceded them, so that after a while these
formed a column of food reaching from the lower part of the pha-
rynx to the stomach. As the difficulty of propelling it into the
stomach increased, the oesophagus became moredistended and pressed
upon the trachea, and thus produced the dyspnoea, and uneasiness.
The difficulty of propelling the food still increasing, it accumulated
in the pharynx, and passed into thd open larynx ; hence the severe
PNEUMOGASTRIC NERVE. 45
paroxysms of dyspncea and suflTocaiton in Exp. XXII. Its passage
into the larynx was, in the two experiments we have just related,
much facilitated by the section of the laryjigealnerwes. It is impor-
tant to observe, that in these experiments, the stomach was found
after death to contain only a moderate quantity of food, notwith-
standing the great distension of the oesophagus.
This distension of the oesophagus after section of ihe par vagum,
in the neck has been remarked by several observers. Some of
these have contented themselves with the simple statement of the
fact; others have attributed it' to paralysis of the oesophagus ; while
others again have referred it to other causes. Baglivi in one expe-
riment found the oesophagus distended through its whole length,
and though he does not state that he attributed this to paralysis of
the oesophagus, yet it is probable, that this was his opinion; for
after stating the circumstance, he adds, "nam cibus in ventriculum
descenderere non poterat."* Valsalva has also observed this re-
tention of the food in the oesophagus, and it is likewise probable
that he believed that it depended upon the same cause ; for after
mentioning that he dissected a dog which died on the tenth day
after section of these nerves, and which had vomited frequently, he
states, "quidquid autem cibi postremis diebus retinuerat, id omne
intra oesophagum ab hujus initio ad sinistrum usque orificium ven-
triculi, nulla ejus facta mutatione, continebatur."t Dupuy distinctly
refers this retention of the food in the oesophagus to its paralysis.^
In several experiments upon the effects of section of the jonewmo-
gastrics in horses, he ascertained that the oesophagus was distended,
while the animals were still alive. That the oesophagus is really
paralysed, it is easy, he says, to convince ourselves, " en mettant
I'oesophage a decouvert. Si on fait boire I'animal, on n'appergait
aucun mouvement dans la membrane charnue de I'oesophage," &c.
Sir A. Cooper§ in his late experiments on the par vagum, after
mentioning this retention of the food in the oesophagus, also refers
it to paralysis of that tube. Several experimenters, however, ex-
plain this distension of the oesophagus differently. The late Mr.
Broughton maintained, that " the parsley found in the oesophagus
must be the result of ineffectual efforts to throw it off the stomach. "||
Dr. Wilson Philip also maintains the same opinion. IT Brachet
seems to think that the oesophagus becomes filled in consequence of
the animal having lost the sense of satiety, and continuing to eat
after the stomach has been distended to the full.** In another place
he seems to admit that the lower part of the oesophagus may be
paralysed.!! Some others seem to think that since the cardiac
* Opera omnia, p. 676, Anvers, 1715.
t Valsalvae Opera cum Epistolis Aatomicis, &Ci J. B. Morgagni, Epist.
Anatom. xiii. 37, Venet. 1740.
X Journal de Medecine Chirurg-ie, &c. Tom. xxxvii. p. 351.
§ Guy's Hospital Reports, Sept. 1836.
II Quarterly Journal of Literature, Science, &c. Vol. x. p. 13.
if Experimental Inquiry, &c. p. 112, ed. 3d.
** Systeme Nerveux Ganglionaire, p. 180, 1830. ff Oper. cit. p. 304.
5*
46 KEID ON THE EIGHTH PAIR OF NERVES.
orifice of the stomach is paralysed, the food is readily forced from
the stomach into the oesophagus. On reviewing Experiments XXII.
and XXIII., and those which we have referred to above, it is at
once apparent, that they are not suflficient, with the exception,
perhaps, of those of Dupuy, fully to invalidate the explanation in
which it is maintained, that the distension of the oesophagus depends
upon the food being forced back from the stomach. Both of the
animals we experimented on, made very frequent efforts to vomit
after eating. It was, therefore, necessary to perform the experi-
ment in another way.
Exp. XXIV. — The pneumogastrics were cut in the neck, as in
the two preceding experiments, in two full-grown rabbits, which
had been made to fast for twenty-six hours. Though the breathing
of these animals was not difficult, it continued to be evidently
somewhat heaving. About an hour after the section of the nerves,
a quantity of parsley was offered to one of them, and it began im-
mediately to eat. The first mouthfuls were swallowed without any
change upon the breathing. Gradually, however, the breathing
became more hurried and laboured as it continued to eat, and when
the dyspnoea had become pretty urgent, it was instantly deprived
of life by a blow upon the head, and before it had given the slightest
indications of any effort to vomit. — Dissection. This was per-
formed immediately after death. The (Esophagus was found filled
throughout its whole length with parsley, and it had evidently
diminished the calibre of the trachea. The stomach contained
but a very moderate quantity of food, and this when examined was
found to consist principally of substances taken the previous day.
In fact, a quantity of parsley, not exceeding a few leaves, was all
that had reached the stomach, and was quite easily distinguished
from the old food. This was lying between the outer surface of
the old food and the inner surface of the cardiac extremity of the
stomach. Not the slightest traces of the parsley could be found in
any of the air-passages. On first exposing the distended oesophagus,
it was observed that irritation of the lower end of the cut pneum,o-
gastrics, both by the forceps and galvanism, produced vigorous
contractions of the muscular fibres of the oesophagus, which ex-
tended over the cardiac portion of the stomach. A similar expe-
riment was performed on the second rabbit, about two hours after
section of the nerves, with exactly the same results. The same
movements were also observed in the oesophagus and stomach,
on irritating the lower end of the cut nerves. Dr. Alison witnessed
the dissection of the first rabbit, and the experiment and dissection
of the second.
We believe that these experiments prove quite satisfactorily,
that the asophagus is distended before the stom,ach, and also fully
bear out the explanation of the phenomena arising from the retention
of the food in this tube which we have given above. It must be
remembered that when the j^neumogasirics are cut in the neck,
even as high as the origin of the superior laryngeals, that the
PNEUMOGASTRIC NERVE. 47
pharynx, and a very small portion of the oesophagus next to it, still
retain their healthy action, for, as we have already seen, these
receive their motor filaments from iho. pharyngeal branches of this
nerve. These parts then continue to act, and propel the food down
the passive CBSophagus, as they would force it into any inorganic
tube. That food should also be sometimes found in the oesophagus
after death in some of those animals which have not fed subsequent
to the section of the nerves, is also exactly what we would expect.
For it is evident, that if efforts at vomiting come on, the powerful
contractions of the abdominal muscles will force the food into
the paralysed oesophagus. It could also easily be shown that the
powerful contractions of the abdominal muscles necessary for
coughing would also force the food from the stomach into the
oesophagus.
This arrestment of the movements of the muscular fibres of
the oesophagus in deglutition after section of \.\\q pneuniogastrics,
when taken along Vv'ilh the fact observed in the two last experiments,
proves, that this does not depend upon any diminution in the con-
tractility of these muscular fibres, but upon a breach being made
in the nervous circle, which, through the intervention of the me-
dulla oblongata, connects the muscular with the mucous coat.
We, therefore, conclude that the muscular contractions of the
oesophagus are not called into action by the ingesta acting directly
as an excitant upon the muscular fibres through the mucous mem-
brane, but by a reflex action, part of the oesophageal filaments of
the par vagum acting as motor, and others, in the manner of
sensitive nerves.* We believe that this fact afibrds a more satis-
factory solution than has yet been offered of a physiological problem
which has lately excited a good deal of attention, viz. whether any
of the sympathetic actions of Whytt, (the "excito-motory actions"
of Dr. M, Hall,) can take place without the intervention of a sensa-
tion. The food is propelled along the oesophagus without our
consciousness and without our volition, and yet we have seen,
that, before the presence of the ingesta in this tube can excite its
muscular fibres to contract and propel their contents onwards, the
same conditions of the nervous system are necessary, as for the
production of those sympathetic or instinctive actions which are not
excited by mental acts.t For, First, an impression must be made
upon the nervous filaments of the oesophageal branches ramified in
the mucous coat. Secondly, This impression must then be trans-
mitted along these filaments to the central organs of the nervous
system. Thirdly, Some other change must be transmitted back-
* Or, to use the phraseology of Dr. M. Hall, the contraction of the cesophagus
in deglutition is an excito-motory action — the filaments of the cesophageal nerves
distributed in the mucous coat being the excitors, and those in the muscular
coats being the reflex or motors.
t Among the sympathetic or instinctive actions which require the intervention
of a mental act, or the excitation of a sensation, we may enumerate laughter,
weeping, &c. These require the agency of the brain for their performance.
48 REID ON THE EIGHTH PAIR OF NERVES.
wards from the central organs of the nervous system (in this case
the medulla oblongata) along the motor filaments to the muscular
coat, by which the stimulation and consequent contraction of the
muscular fibres are produced.* We have here, then, a natural
sympathetic action in the human body occurring without the inter-
vention of a sensation, and simply because the presence of such a
sensation is not necessary for the proper performance of this
function. From this and other facts which have been adduced in
discussions on this question, I think we are fully entitled to argue
that sensation is not a necessary condition for the production of
those sympathetic actions with which it is so closely linked.
Besides, it can be shown that these sensations have been connected
with their attendant movements for an evident purpose; and if this
purpose is one which is not necessarily instrumental in the pro-
duction of the movements themselves as muscular movements, but
to further the ends for which they were designed, we have already
succeeded in obtaining a sufficient reason for the presence of these
sensations, without being obliged to believe that they are actually
concerned in the production of these movements. To illustrate my
meaning by an example; — when the bladder and rectum are filled
by their usual contents, certain impressions are made upon the
5joz;z«/ sensitive nerves distributed in their mucous coat, and these,
when conveyed to the central organs of the nervous system,
excite certain sensations ; upon this certain muscular movements
follow, by which the contents of these organs are expelled. Now
the presence of the sensations is no absolute proof that their excita-
tion is necessarj'' for the performance of these muscular movements,
for it must be at once obvious, that they here serve most important
purposes, independent of any supposed influence exerted in the
actual production of the movements. For if these muscular move-
ments by which the contents of the rectum and bladder are expelled,
were always to occur when the impressions were made, very
serious inconveniences would evidently be occasioned. It is neces-
sary, then, for our own comfort and well being, that these move-
ments should be influenced to a very considerable extent by volition ;
and of course this could only be accomplished by associating
sensation with the excitation of the impression. When we take
these circumstances along with the experiments we have stated, we
may, I believe, safely conclude, that these sensations are not con-
cerned in the production of these movements, as muscular move-
ments, but have been superadded for an ulterior purpose. The
same kind of reasoning could easily be applied to all the other
instinctive and sympathetic actions found conjoined with sensation
in the healthy condition of the body, but which do not require the
intervention of the brain for their performance.t
* Mr. W. B. Carpenter has given a very excellent tabular arrangement of the
voluntary and instinctive actions, accompanied with some very perspicuous
remarks. Number 132 of this Journal.
f These sympathetic or " excito-motory movements" were well known, and
PNEUMOGASTRIC NERVE. 49
The results obtained from these experiments upon the oesopha-
geal branches of the par vagum, are at direct variance with the
Hallerian doctrine, that the muscular fibres of the oesophagus are
called into contraction by a direct impression. Though this does
not occur in the healthy condition, it is probable that both the
muscular fibres of the oesophagus, and also the principal closing
muscles of the glottis, may be called into action by a direct im-
pression, when the mucous surfaces of these organs are inflamed.
For we find in many cases of disease or injury of the spinal chord,
that the bladder ceases to expel its contents. In some of these cases,
as I have myself seen, the urine after a time no longer requires to
be drawn off by the catheter, but is constantly expelled as soon as
it has accumulated in small quantities. On dissection of such cases
after death, the mucous coat is found thickened and inflamed, and
the muscular coat is greatly increased in strength and contracted
upon itself. We believe that the explanation of such cases is this,
that as long as the mucous coat is in a healthy condition, the urine
fails to excite the action of the muscular coat by a direct impression,
but when the former becomes inflamed this is efiected.
The arrestment of the movements of the cesophagus in deglu-
tition after section of the par vagum completely invalidates the
evidence adduced by Brachet,* in favour of the dependence of the
sense of satiety upon the integrity of thejoar vagum. We do not
wish to deny that this may be the case ; we only mean to affirm
that the data upon which Brachet rests his conclusions are obviously
insufficient.
Cardiac Branches of Par Vagum. — It may be considered as
perfectly ascertained by numerous observers, that section of the
par vagum above the origin of the cardiac branch of this nerve does
not materially affect the heart's action, and that the sudden death
occasionally rem.arked after the division of these nerves, and which
some of the early experimenters attributed to arrestment of the
action of this organ, was in fact dependent upon the suffocation of
the animal, by suspending the movements of the muscles of the
glottis. We may then, I believe, fairly attribute the increased
frequency of the pulsations of the heart, observed during and for
described by Whytt and Monro. That some of them do not require the ag-ency
of the brain for their performance was clearly proved by the experiments of Blane,
Legallois, Flourens, and others. It was also stated previous to the appearance
of the publications of Dr. M. Hall, that these movements were independent of
sensation. Sir G. Blane, for example, Avhen relating the experiments referred to
above, states, "that there are facts which show that instinctive actions, even in
animals endowed with brain and nerves, do not depend on sensation. (Lectures
on Muscular Motion, read at the Royal Society in 1788.) Dr. M. Hall, availing
himself of the late discoveries, by which it has been shown that the nervous
filaments which transmit impressions to the central organs of the nervous system,
are distinct from those which convey the motive influence back to the muscles,
has extended and more fully illustrated this view of the independence of these
sympathetic movements upon sensation, and has formed it into a kind of Corps
de Doctrine.
* Oper. cit. Exp. 50 and 53.
50 EEID ON THE EIGHTH PAIR OF NERVES.
some minutes after the experiment, to the struggles and terror of
the animal, for in a shoi't time the action of the heart is as slow and
vigorous as before the section of the nerves. Though the con-
tractility of the heart is independent of the brain and spinal marrow,
yet we know, from the experiments of Legallois, Wilson Philip, and
others, that injuries of these organs influence the contractility of the
heart in a most important manner. A sudden injury extending to a
considerable portion of the brain arrests or at least much enfeebles the
heart's action, and the extent to which the contractions of this organ
are affected by mental emotions is well known. It is generally
believed that it is through the cardiac branches of the par vcigum
that this influence is transmitted from the brain to the heart ; but
I am not aware that there are any decisive facts in proof of this
opinion.
Exp. XXV. — Two rabbits were killed by crushing the brain
extensively and suddenly by blows with a hammer. In one of
these a portion of each of the pneumogastrics above the origin of
the superior laryngeals had been removed. On exposing the heart
of the rabbit in which the nerves were left entire, which was done
as expeditiously as possible, these contractions of the heart were
extremely rapid and very feeble. On exposing the heart of the
animal, in which the nerves had been previously cut, which was also
doneinimediately after the brain had been crushed, the action of the
heart was evidently much slower and more vigorous than in the other
animal. This comparative experiment was again repeated with the
same results. The action of the heart was also examined in other
two rabbits, on which the pneumogastrics had also been previously
divided in a similar manner before the brain was crushed, and in
neither of these did it present the same rapid and feeble movements,
which I have always seen when these nerves were entire.* Now
since the contractility of the heart can also be effected by extensive
and sudden injury of the spinal chord after the brain has been
removed, it would appear that the influence of causes acting on the
central organs of the nervous system may be transmitted to the heart
by two channels, viz. by \\\q par vagum, and by the sympathetic
system. In these experiments, the trunk of the sympathetic in the
neck was divided along with the par vagum,, but this of course
could not affect the greater number of the sympathetic nerves passing
to the heart.
Pulmonary Branches of the Par Vagum. — The only method
of experimenting on the pulmonary branches of the par vagum
which we can adopt in the living animal, is that of cutting the trunk
of the nerve itself, as it lies in the neck.
Effects of Section of one Pneumogastric Nerve upon the Lung
of that side. — About two years ago I commenced, at the suggestion
of Dr. Alison, a series of experiments upon the effects of section of
* Dr. Alison was present at one of these experiments, and made the same re-
mark.
PNEUMOGASTRIC NERVE. 51
the pneumogastric nerves upon the respiratory murmur, as It
might probably enable us to ascertain what is the cause of the first
departure from the healthy condition of the lungs after section of
these nerves. As I was led by the statements of Wilson Philip* to
believe that section of one of the pneumogastrics would produce
the usual morbid changes in the lungs which are observed after the
section of both, and by the results of the experiments of Magendiet
and Mr. Svvan,± to expect that these would be confined to the side
operated upon, I selected this method of experimenting, as the sound
lung in that case would afford an accurate standard of comparison,
by which to judge of the changes eifected. No doubt the well-
known experiment of Haighton§ is inconsistent with the supposition,
that section of one of the nerves destroys the function of the lung
on the same side ; but as he simply divided the nerve without re-
moving a portion of it, the re-union of the cut ends might have
occurred before a sufficient time had elapsed to permit these morbid
changes to be effected. I have removed a portion of ihepar vagum
in fourteen animals, and have never yet observed any morbid struc-
tural change which I could attribute to the section of the nerve. Two
of these were calves, and were killed about twenty-four hours after the
section of the nerve : seven of them were dogs, and were allowed
to live from four to ten days : three rabbits were allowed to live
a fortnight : one rabbit lived three months, and one rabbit was killed
after six months. None of these animals appeared to suffer any bad
consequences from the operation. The dogs breathed easily, and ate
and digested as before ; the rabbits also were as lively and active
as ever, after the operation. No morbid changes, as I have said,
could be observed in the lungs of the calves and dogs after death.
The three rabbits which were allowed to live for a fortnight were
apparently in perfect health when killed, and the lungs were shown
to my friend Dr. Knox, who was at the same time requested to
examine if there was any structural difference between the lungs of
the opposite sides, but he could perceive none. The rabbit which
lived three months died of recent pneumonia, affecting both lungs
equally. The lungs of the rabbit killed at the end of six months
were perfectly healthy. In all these experiments, a sufficiently
large portion of the nerves was removed to prevent their re-union.
The morbid changes on the lung in the side on which the nerve had
been cut, observed by Magendie and Swan, must have been ac-
cidental. The experiments which I have mentioned are sufficiently
numerous to entitle us to conclude, that lesion of one of the pneu-
mogastrics does not necessarily, or even generally induce disease of
the lung of that side. This does not appear so remarkable, when
we remember the free anastomoses between the pulmonary plexuses
of the two sides.
Effects of Section of the Par Vagum. upon the respiratory
* Oper. cit. p. 145. f Oper. cit. 401.
X Essay on the Connection of the Heart and Arteries, and the Functions of the
Nervous System, &c.
§ Medical Facts and Observations, Vol. vii. p. 163. Experiment IV.
52 REID ON THE EIGHTH PAIR OF NERVES.
muscular movements. — As the pulmonary branches of the pneu-
mogastrics are the only nervous filaments which the lungs receive
from the cerebro-spinal axis, we would expect, in accordance with
the generally received notions on the physiology of the nervous
system, that all the impressions made on the mucous surface of the
lungs which excite the sensations and sympathetic movements con-
nected with the respiratory functions, are conveyed to the cerebro-
spinal axis through this nerve. And this opinion is strengthened
by the experiments of Legallois and Flourens, by which it was
shown, that though all the other parts of the encephalon above that
portion of the medulla oblongata to which the par vagum, is
attached, could be removed without arresting the respiratory mus-
cular movements, yet these instantly ceased, when this part of the
nervous system was injured. And it is further well known, that
if the spinal marrow is cut across, all the respiratory muscles are
paralysed which receive their nerves from that portion of the
spinal chord below the point divided, while those which receive
their nerves from that portion of the spinal chord which remains
in connection with the medulla oblongata, continue to perform
their usual functions. From these and other facts, it may be con-
sidered as ascertained, that all the impressions made at the lungs
must be conveyed to the medulla oblongata, before they can excite
sensations or sym.pathetic movements. That the par vagum. can
convey these impressions from the lungs, is not only rendered pro-
bable by the connection of the par vagum with the 7nedulla oblon-
gata, but may be considered as proved by the results of the experi-
ments upon section of the spinal chord, to which we have just
referred. It, however, by no means necessarily follows, that this
is the sole channel by which these impressions are conveyed to the
■medulla oblongata^ for it is possible that these might reach the
spinal chord through the branches of the sympathetic distributed
upon the lungs, and in this way be conveyed upwards to the
medulla oblongata. This last supposition is certainly not a very
probable one, and can only be admitted after satisfactory evidence
in its favour.
We shall now examine how the facts accord with the theories
on this question. That the respiratory movements continue after
section of both pneumogastrics is now universally admitted, but
physiologists are by no means agreed in what manner these pro-
ceed. Those who believe that the movements of the respiratory
muscles are usually carried on by the exercise of volition, will of
course maintain, that these proceed exactly in the same manner as
before the section of the nerves. This being, however, an untena-
ble supposition, we shall not discuss it further. Those, on the
other hand, who maintain that this function, though capable of
being influenced and controlled to a very considerable extent by
volition, is nevertheless generally performed without our volition,
and in consequence of impressions made at the lungs and con-
veyed to the medulla oblongata, must of course believe that this
function is carried on differently after section of these nerves, from
PNEUMOGASTEIC NERVE. 55
what it is in the natural condition of the body. Brachet asserts that
an animal continues to breathe after section of the pneuinogastrics^
because it has acquired the habit of using the respiratory muscles.*
Dr. Marshall Hall believes that when these nerves are divided,
the function of respiration is no longer an involuntary ^d a sym-
pathetic movement, or, as he expresses it, excito-motory, h\ii is
now a cerebral function, or, in other words, is performed by an act
of volition.! That these movements continue after section of the
pneumogastrics, and under circumstances where it is impossible
that they can be carried on by an act of volition, I have been reluc-
tantly compelled to believe. For I am satisfied that these respira-
tory movements will not only go on regularly and vigorously for
hours together in kittens one and two days old, but that they w-ill
also proceed in animals deprived of all volition by a small dose of
prussic acid.l Thinking that it might be possible, though certainly
not probable, that the impressions made at the lungs might in these
cases reach the medulla oblongata through the free anastornoses
between the laryngeal nerves at the larynx, (for in the first experi-
ments I cut the nerves, as is generally done, in the middle of the
neck,) I proceeded to repeat the experiir^ents by dividing the nerves
near the base of the cranium, and above the origin of the superior
laryngeals. The results, however, were the same as when the
nerves were cut in the usual manner.
We are next naturally led to inquire, how the sensation arising
from the ivant of fresh air in the lungs, or the besoin de respirer,
is affected by section of these nerves? Brachet§ has related some
experiments, vvhich appear. to prove, in a very conclusive manner,
that this besoin de respirer is annihilated by section of the pneumo-
gastrics. Though I considered the details given by Brachet as not
satisfactory on some points, yet, after reading them, I had no doubt
of the accuracy of his opinion. I am. now, however, perfectly
satisfied, from numerous experiments, that an animal will continue
to evince great uneasiness after section of these nerves, when the
access of air to the lungs is prevented. I have repeated these
experiments in several ways, and with the same results. One of
the methods followed was this.
Exp. XXVI. — The par vagum was cut on both sides in two
kittens ten days old. When one of these nerves was cut, the
blood in the carotids became dark-coloured, but it soon after re-
sumed its natural appearance. When both nerves were cut, the
blood in the carotids again became dark, the animal began to
struggle, and it was necessary to open the trachea to prevent their
immediate sufibcation. After the trachea was freely opened, the
* Oper. cit. p. 132, "a I'habitude que le systems nerveux cerebro-spinal a
contractee de faire mouvoir les muscles respirateurs." How an animal could
contract the habit of performing an involuntary action, it would certainly be diffi-
cult to explain. f Phil. Mag. Jan. 183.5, and Lect. on the Nerv. Syst., p. 25. '
X In one dog in which these nerves were divided, the respiration continued
above twenty minutes after we had satisfactory evidence that the sensorial func-
tions were arrested. § Oper. cit. p. 133-4-5.
m 6
54 REID ON THE EIGHTH PAIR OF NERVES.
blood in the carotids again assumed its arterial colour. Both ani-
mals struggled, made violent inspirations, and appeared to suffer
great uneasiness when the access of air to the lungs was prevented.
On compressing, for example, the exposed trachea with the forceps,
the animals lay quiet for a few moments, making several inspiratory
efforts gradually increasing in force and extent ; after a few moments
more, the inspirations became heaving, and they began to struggle
and appear very uneasy.
This experiment was repeated with similar results upon a kitten
two days old. The nerves in this last experiment were cut above
the origin of the superior laryngeals. I have also performed a
similar experiment upon several rabbits and dogs. In all of these
animals the breathing became very laboured, and the animal evinced
every indication of great uneasiness, when the access of air to the
lungs was suddenly d^ndi fully prevented.
From these experiments I conclude that section of the par vagum,
on both sides, neither arrests the transmission of those impressions
made upon the mucous surface of the lungs, by which the respira-
tory movements are excited ; nor does it annihilate the sense of
anxiety arising from the want of fresh air in the lungs. We are
obliged, then, to suppose, that these impressions are conveyed back-
wards by the sympathetic branches distributed upon the lungs to
the spinal chord, and thus pass upwards to the medulla oblongata.
As has been already stated, we believe that these impressions may
also be transmitted through the par vagum. It is quite possible
that the latter is the usual channel by which these are transmitted,
and it is only when they become more intense that they pass along
the other course we have mentioned. This may, perhaps, explain
the slow respiration occasionally observed after section of the
pneumogastrics. It is certainly contrary to the usually received
physiological doctrines to suppose that the sympathetic system can,
in the healthy state of the nerve, and of the parts upon which it is
distributed, transmit those impressions by which the natural sensa-
tions and sympathetic movements are excited, but I cannot see
how the facts can otherwise be explained. The peculiar pain felt
on bruising the healthy testicle, and which we are led to believe
depends upon the sympathetic, may also induce us to believe that
a previously inflamed condition of the filaments of this nerve is not
absolutely necessary to enable it to transmit those impressions
which excite sensation.
Brachet* has also detailed several experiments which seem satis-
factorily to prove that all the sensations occasioned by the presence
of foreign bodies, &c. in the air-passages are dependent upon the
integrity of the pneumogastrics. I have repeated these experi-
ments on several dogs and cats, but have not yet been able to arrive
at any conclusive results. The chief difficulty which I have expe-
rienced in making any satisfactory experiments on this question,
has arisen from the great insensibility of the mucous membrane of
the lungs in the healthy state. I have never yet been able to
* Oper. cit. p. 157-8-9.
PNEUMOGASTRIC NERVE. 55
induce the severe paroxysms of coughing described by Brachet,
by any mode of irritating the inner surface of the trachea and
bronchi which I have adopted, if care were taken to prevent the
application of these irritants to the inner surface of the larynx,
when the superior laryngeals were entire. I injected by a syringe
two drachms of alcohol, slightly diluted, down the trachea of one
dog, and as much cau de cologne into that of another, when both
nerves were entire, without exciting any decided cough. The fric-
tion of a probe against the inner surface of the trachea and bronchi
never produced cough. Though I have seen some reason to doubt
that these sensations of the mucous surface of the lungs are affected
to the extent stated by Brachet, yet I do not at present wish to offer
an opinion upon this subject, until I have investigated it more
thoroughly. I would only suggest at present, that it is possible
that Brachet in some of his experiments may have overlooked a
source of fallacy which would very seriously interfere with the
results, — and that is, the facility with which some of the irritants
used might reach the interior of the larynx; for it is to be remem-
bered, that the nerves were cut below the origin of the superior
laryngeals. If the head be depressed when a quantity of fluid is
thrown into the trachea, or if the fumes from a muriatic acid bottle
are used as an irritant, (as by Brachet in some of his experiments,)
the chances are, that a part of these will reach the interior of the
larynx, and excite violent efforts to cough. Perhaps this may ex-
plain in some measure the discrepancy between the results obtained
by Brachet upon the sensibility of the mucous membrane of the
trachea, and those obtained by practical surgeons in operations on
the human species, and in some experiments by Haller* upon ani-
mals. Some of the animals I experimented on did cough slightly
wrhen fluids were injected into the trachea before the nerves were
cut, — at least in the imperfect manner in which an animal must do
when the trachea is opened.
Morbid changes iri the Lungs after section of the Pneumo-
gastrics. — Section of the pneumogastrics invariably proves fatal if
the cut ends of the nerves are kept apart. The animal seldom if
ever lives beyond three days, and generally dies sooner ; but when
the cut ends of the nerves are allowed to remain in contact, it some-
times lives ten or twelve days. There can be now no doubt that
the section of these nerves proves fatal by its effects upon the
lungs. The congested state of the blood-vessels of the lungs, and
the effusion of frothy serum into the air-cells and bronchial tubes,
may be considered as the characteristic and only constant appear-
ance after death from section of the pneumogastrics. I am of
course here supposing that the air is allowed to pass freely into the
lungs. It is quite evident that section of these nerves does not
prove fatal by removing any innervation necessary for effecting the
changes by which the venous blood is converted into arterial, as
Dupuytren supposed ; nor by coagulating the blood of the pulmo-
* Opera Minora, Tom. i. p. 402, Laus. 1762; or Sur la Nature Sensible et
Irritable, Tom. i. p. 394, Laus. 1756.
5(6 REID ON THE EIGHTH PAIR OF NERVES.
nary arteries, as Mayer maintains. The first point to ascertain in
an investigation of this kind, is the first departure from the healthy
condition of the organ, — to decide whether the eff'usion of the
frothy reddish serum, by interfering with the usual changes of the
blood in the lungs, causes the congested state of the pulmonary
blood-vessels, and the severe dyspnoea, as is usually imagined ; or
whether this effusion is the effect of a previously congested state of
the pulmonary blood-vessels and its attendant dyspnoea. If it be
made out that the fatal dyspnoea is not the effect of the effusion of
serum, we have next to inquire what is the probable cause of this
congested state of the pulmonary blood-vessels and the accompany-
ing dyspnoea. I have been collecting for some time past a con-
siderable number of facts on these questions, but have not yet been
able to obtain what I consider satisfactory data. Upon the discus-
sion of this subject I shall not at present enter, but reserve it for
another opportunity. If I hazard a kw remarks upon this question,
I wish that they may be looked upon as conclusions in which I
myself do not place any very great confidence, until I have been
more thoroughly satisfied of their accuracy. I am at present inclined
to believe, from the experiments which I have made, that this frothy
serous effusion is the result of the congested state of the pulmonary
blood-vessels attending the severe dyspnoea which precedes death,
and not the cause of this dyspnoea. The grounds on which I have
adopted this opinion are these, l.s^, This frothy serous effusion is
exactly similar to the fluid in the air-passages in death from what-
ever cause, when preceded by protracted and severe dyspnoea.
2dly, The extent of this effusion appears to be proportionate to the
duration and severity of the dyspnoea preceding death. Sdly, Dysp-
noea is sometimes present after section of these nerves when the
passage of air into the lungs is quite free, and before any serous
fluid has been effused. What is the cause of the dyspnoea and con-
gestion of the pulmonary vessels I have not yet been able to satisfy
myself, but I believe it probably depends upon paralysis of the
muscular fibres of the bronchi. If these muscular fibres move in
unison with the muscles of respiration, like those of the larynx
supplied by the same nerve, they must exert a very important
influence over the renewal of the air in the lungs. That we are not
conscious of any such m^ovements cannot be urged as an objection
to this view, after what we have seen in the oesophagus. Of the
existence of the muscular fibres of the bronchi described by Reis-
seissen there can be no doubt, I have seen these muscular fibres
very distinctly in some of the smaller bronchial tubes. I have
observed a circumstance in experiments upon dogs, which, if con-
firmed by more extended investigation, may throw some light upon
this question. In four dogs in which the par vagum was cut on
one side, the respiration of the same side, though quite natural
immediately after the operation, became distinctly bronciiial after a
few hours. This continued for two or three days, and the natural
respiratory murmur gradually returned. One of these dogs was
killed during the continuance of this bronchial respiration, and no
SPINAL ACCESSORY NERVE. 57
structural change could be detected in the lung. As I have, how-
ever, some reason to doubt from late experiments whether this is a
constant occurrence, I shall defer its consideration until I have made
more extended observations. I am inclined to believe from what I
have seen, that pneumonia is a pretty frequent occurrence after sec-
tion of these nerves.
Gastric branches of the Par Vagum. — As my experiments on
these branches are not yet completed, I shall reserve this part of
the investigation for a future opportunity.
PART III.
Spinal Accessory Nerve.
Before stating the experiments which I have made upon this
nerve, I wish to advert for a little to its origin and distribution, and
in this I shall restrict myself to those points which are most inti-
mately connected with the discussions upon its functions. The
origin of the spinal accessory from the spinal chord is sometimes
higher and sometimes lower, but we have the authority of Huber,*
Lobstein,t and Bellingeri,± who have attended particularly to this
subject, in stating that it most frequently commences opposite the
sixth or seventh cervical nerves. This nerve, in its course upwards
to the foramen magnii'm, is placed between the posterior roots of
the spinal nerves and the ligamentuTn denticulatum, aiwA receives
its filaments, as Bellingeri§ has clearly demonstrated, from the
lateral or middle column of the spinal chord. The filaments of the
spinal accessory may come entirely from the middle column of
the spinal chord, or it may also receive some filaments from the
posterior roots of the first and second cervical nerves. These
filaments, from the posterior roots to the spinal accessory, when
present, rarely come from the second, but generally from the first
cervical. When they come from the posterior root of the second
cervical, they are few in number. Those from the first cervical
vary considerably in number; for we find sometimes a few, some-
times the greater part, at other times the whole of the filaments of
this root passing to join the spinal accessory. This junction be-
tween these two nerves may be confined to one side of the spinal
chord, or it may be present on both. This communication between
the posterior roots of the first cervical and the spinal accessory is
* Huber says at p. 13, " De Medulla Spinali et Specialim de Nervis ab ea
Provenientibus," that it commences opposite the seventh cervical, but he after-
wards places it opposite the sixth.
t Lobstein (De Nervo Spinali ad Par Vagum Accessorio, p. 341, Tom. i.
Thesaus. Diss. Sandifort, 1768,) says it commences under the sixth pair of
cervical nerves by a slender beginning.
X Bellingeri (De Medulla Spinali, Nervisque ex ea Prodeuntibus, p. 74,
1823,) adopts the description of Huber where he states that it commences
opposite the seventh.
§ Op. cit. p. 51 and 55. See also Ed. Med. and Surg. Journ. Vol. xliv. p. 396.
6*
58 EEID ON THE EIGHTH PAIR OF NERVES.
far from being rare, and Lobstein asserts that it is more frequently
present than absent.* When the posterior root of the first cervical
joins itself to the spinal accessory, a branch of equal size leaves
the trunk of the accessory, either at the point where it is joined by
the posterior root, as figured and described by Asch,t or from three
to six lines above this junction, as figured by Huber,J and described
by Bellingeri.§ This branch, after leaving the accessory, proceeds
outwards, approaches the anterior root of the first cervical, and
takes the place of the posterior root. When the posterior root of
the first cervical comes from the accessory, it generally swells into
a ganglion in the usual position. Sometimes, however, though
rarely, a ganglion is found where the posterior root leaves the
accessory to join itself to the anterior root. This ganglion was
first pointed out by Huber, and its existence has been denied by
Lobstein, Asch, Haller, and Scarpa, and has again been described
by Bellingeri. I have seen this ganglion once, and it was present
on one side only. It becomes an interesting question, to know
whether or not the whole of the filaments joining the accessory
from the posterior roots of the spinal nerves, leave it again to form
the posterior root of the Jirst cervical. Bellingeri answers this
question in the affirmative. — " The filaments coming from the
posterior roots to the accessory are not intermixed, but only
approximated, so that they can be separated by slight traction." |1
And in another place he says, "I believe that the filaments from
the posterior roots which join the accessory, leave it again to
proceed to the posterior root of the first cervical. "IT From this he
concludes that this nerve contains no sensitive filaments. Miiller**
adduces some unusual appearance in this nerve, observed by Hyrtl,
Remak, and himself, which would seem to favour the opinion, that
it contains some sensitive filaments, independent of those which it
occasionally receives from the posterior roots. "I do not, however,
affirm," he says, " that the spinal accessory always contains a
sensorial element, but leave it doubtful." — "But in the case," he
continues, "where the nervus accessorius forms an intimate con-
nexion with the posterior root of the first cervical or any other
nerve, we may suppose an interchange, and this in the same degree
will render probable the idea of Monro, that the communication of
the spinal accessory with the posterior root of the first or any other
spinal nerve will be an equivalent to it for a posterior root."tt The
only other point connected with the anatomy of this nerve to which
we shall here refer, is its connexion with the par vagiim, for we
shall have occasion to allude to it repeatedly, when examining the
functions of this nerve. As the spinal accessory is passing through
the foramen lacerian it divides into two branches, — an internal
* In speaking of the filaments which form this communication he says, " com-
municationem illud notamus quod scepius accessorium subire quam eundem
intactum relinquere observentiir."
f De Primo Pare Nervorum Medullas Spinalis, Tab. x. fig. ii. et Explicatio,
p. 335. Ludwig, Sc. Nerv. Min. tSel. Tom. i.
X Open cit. § Ibid. p. 80. || Ibid. p. 81. IT Ibid. p. 78.
** Arch, fiir Anat. und Physiol. No. 3. 1837. ft Oper. cit. p. 379.
SPINAL ACCESSORY NERVE. 59
and an external. The internal, after giving off some filaments to
assist in forming the pharyngeal branch of the pai' vagum,, becomes
incorporated with the filaments of the trunk of the nervus vagus.
The nervus vagus swells into a ganglion {ganglion secundum
nervi vagi), where it is joined by the internal branch of the acces-
sory, and by branches from the sympathetic. This ganglion is
very distinct in the lower aninials. Bischoff* states that he ascer-
tained by dissections of the Mammalia that only a part of the fibres
pass into the ganglion, and that the others retain their fibrous
character. He also adds, that it is evident that those which form
the ganglion belong to the par vagum, while those which do not
enter into its formation belong to the internal branch of the acces-
sory. From this gangliform swelling the superior laryngeal nerve
arises. The external branch proceeds outwards, perforates the
upper part of the sterno-cleido-mastoideus, sends filaments to this
muscle, and to the trapezius, and forms at the same time several
anastomoses with branches from the cervical plexus. The peculiar
origin and course of this nerve, and particularly its intimate con-
nection with ihe par vagum, have formed the basis of most of the
speculations on its functions since the time of Willis. It was
maintained by Willist that this nerve, from its connexion with the
par vagum, regulated those involuntary movements of the neck
and arm connected with the emotions and passions. Lobstein also
believed that the spinal accessory joins itself to the vervus vagus
for the purpose of connecting it with the involuntary functions, J
and he supposed that paralysis of this nerve might also affect the
movements of the phari/ 77x and larynx.^ Others have maintained
that it is a nerve of involuntary motion, from the particular portion
of the spinal chord from which it arises. It is, as is well known,
one of Sir C. Bell's respiratory nerves, arising, as he supposes,
from a particular tract in the spinal chord. According, then, to
Sir C. Bell, it is a nerve of involuntary motion. Bellingeri believes
that the lateral tract of the spinal chord from which the accessory
arises, presides over the instinctive and sympathetic movements,
and consequently this nerve must be one of involuntary motion. ||
Arnold,!F Scarpa,** and Bischoff'tt, maintain that the accessory stands
in the same relation to the nervus vagus which the anterior roots
of the spinal nerves do to the posterior. J J These nerves, as they
lie in the foramen lacerum, do certainly resemble very closely in
appearance, the anterior and posterior roots of the spinal nerves.
The junction of the internal branch of the accessory with thejoar
vagum beyond the part where it swells into its superior ganglion
increases the resemblance still farther. To this opinion we shall
* Ibid. p. 22.
t Cerebri Anatome, &c. Cap. xxviii. X Oper. cit. 346.
§ Oper. cit. 345. || Oper. cit. p. 89-90.
\ Der Kopftheil des vegetativen Nerven-Syst. Heidel. 1831.
** De Gangliis Nerv. deque Essentia Nervi Intercost. Ann. Univers. de
Medicine, 1831. ff Oper. cit.
XX I'' appears that this idea had been previously stated by Gorres, (Exposition
der Physiologie. Coblentz, 1805.)
60 REID ON THE EIGHTH PAIR OF NERVES.
have again to refer. With these preliminary remarks I shall now pra-
ceed to give the results obtained from my experiments on this nerve.
Effects of irritating this Nerve in the Living and recently
killed Animal. — These experiments on the living animal were per-
formed on the external branch of the accessory before it perforates
the;upper part of the sterno-mastoid, as it is impossible to operate
on t^e trunk of the nerve unless it is exposed within the cranium.
Irritation of this nerve by the forceps in the living animal produces
vigorous convulsive movements of the sterno mastoid and trape-
zius as was remarked by Dr. M. Hall and Mr. Broughton in their
experiments.* This mode of irritating the nerve is not attended
by any indications of suffering, unless the nerve is strongly com-
pressed between the blades of the forceps. When the nerve is
firmly included in a ligature, the animal gives very decided evidence
of suffering pain. When the nerve has been firmly lied or cut
across, irritation of the lower end is attended by the same convulsive
movements of the muscles, while irritation of the upper end, or that
in connexion with the spinal chord, is unattended by any muscular
movements. The same muscular movements are observed on irri-
tating the nerve in the recently killed as in the living animal. From
these experiments we conclude that the filaments of the external
branch of the spinal accessory are principally motor, and that the
sensitive filaments must be very few in number. Whether those
sensitive filamentsbelongoriginally tothenerve,or whether it derives
them from the other nerves at the base of the cranium, with which
it anastomoses, we cannot at present determine.
Effects of the Division of these Nerves. — According to Sir C.
Bell, the section of the spinal accessory paralyses the muscles to
which it is distributed, as muscles of respiration, though they still
retain their voluntary movements through the media of the spinal
nerves. This appears to be established by the following experiment
performed by Mr. Shaw. " The par vagum of an ass was first
divided, with the intention of causing difficult and laboured respira-
tion. When all the respiratory apparatus was in great agitation,
and when the sterno-maxillaris (the same as the sterno-cleido-mas-
toideus in man) was especially in action, the spinal accessory was
divided. In an instant the sterno-maxillaris ceased to act as a
muscle of respiration, but when the animal struggled to get free, it
became rigid, showing that through the plentiful supply of spinal
nerves it still retained its office of moving the head and neck."t
That part of the experiment which relates to the cessation of the
respiratory movements of ihe sterno-maxillaris being a negative
observation, ought, we think, to have been repeated and further
confirmed, before such important conclusions were drawn from it.
I have removed a portion of the external branch of this nerve on
one side, as it issues from the foramen lacerum in seven dogs, with-
out observing any change upon the ordinary voluntary movements
of that side of the neck. It is possible, however, that if the animals
* Fourth Report of British S. Association.
t London Medical and Physical Journal, Vol. xlix. p. 459.
SPINAL ACCESSORY NERVE. 61
had any violent voluntary efforts to make with the muscles of the
neck, that those of the side on which the nerve had been cut might
have acted less vigorously than those of the opposite side. I then
proceeded to endeavour to ascertain the effects of the section of this
nerve upon the involuntary respiratory movements of these muscles.
The experiments were performed on dogs and cats.
The plan which I followed appears to me to be more likely to lead
to accurate results than that adopted by Mr. Shaw. In the method
followed by Mr. Shaw the animal might use these muscles volun-
tarily when the breathing was rendered difficult, and therefore
lead to erroneous conclusions. Besides, the difficulty of recognizing
the movements of any particular muscle through the skin of the
animal, (at least in the kind of animals I operated on,) when so
many other of the neighbouring muscles are in movement, must
also be apt to mislead. The plan which I adopted was this. A
small dose of prussic acid was given to an animal on which the
spinal accessory had been previously divided on one side. After
the convulsive movements produced by the effects of the acid had
ceased, the anim.al was generally found in a state similar to what
we sometimes see in apoplexy, — the action of the heart went on,
and the respiration was slow, heaving, and performed at considerable
intervals, while the sensorial functions appeared to be completely
suspended. The animal had undoubtedly lost the power of making
the slightest voluntary effort. The respiratory movements always
ceased before the action of the heart, but they continued in several
of these animals sufficiently long to permit us to lay bare all the
muscles of the anterior part of the neck, and to make accurate obser-
vations. The sterixo-mastoids in dogs and cats appear to have
little action as respiratory muscles ; for in some of these experiments
though the sterno-hyoid d^nd thyroid muscles acted very powerfully
in unison with the other muscles of inspiration, and the head was
pulled towards the chest at each inspiratory movement, yet no con-
traction could be perceived in the sterno-Tnastoid, neither in the
side on which the nerve had been cut, nor on that on which it had
been left uninjured. In one dog, distinct muscular movements
were observed in a bundle of muscular fibres, which arise from the
humerus, run up along the outer margin of the sterno-Tnastoid, and
are inserted along with it. This muscular bundle receives filaments
from the accessory. In two dogs and one cat in which the head
was fixed, and where these respiratory movements were particularly
vigorous, distinct movements of contraction and relaxation were
observed in the exposed sterno-niastoid mw^tX^^, synchronous with
the other muscles of respiration. These were, perhaps, somewhat
weaker on the side on which the nerve had been cut. In one
of these dogs similar movements were observed in the trapezius
on the side on which the nerve had been divided. From these
experiments we conclude, that the sterno-cleido-mastoideus and
trapezius can assist in the involuntary movements of respiration
after section of the spinal accessory, and therefore it cannot be
called the special respiratory nerve of these muscles. As far as we
62 REID ON THE EIGHTH PAIR OF NERVES.
can observe, the functions of the external branch of the spinal
accessory exactly resemble those of the filaments coming from the
cervical plexus with which it anastomoses so freely. Future ana-
tomical researches may perhaps explain to us how it follows this
peculiar course, without obliging us to suppose that it has a reference
to any special functions in the adult of the human species.
We now proceed to inquire what are the functions of the inter-
nal branch of the spinal accessory? We have already stated that
Arnold, Scarpa, and Bischoff'have imagined that the spinal accessory
stands in the same relation to the par vagum as the anterior roots
gf the spinal nerves do to the posterior. If this view be correct, the
internal branch of the accessory must furnish the motor filaments
oii\iQ par vagum, and upon it must depend the important muscu-
lar movements of the pharynx, larynx, and oesophagus. As no
anatomist has yet succeeded in tracing for any great distance the
filaments of the accessory, separate from those of the trunk of the
nervus vagus, it is therefore impossible to decide this question
satisfactorily by the anatomy alone of the nerves.* Bischoff pro-
ceeded to submit this opinion to the test of experiment, by endea-
vouring to ascertain what effects section of the trunk of the accessory
within the cranium would have upon the voice. After relating
several failures upon dogs, in which the animals either died from
hemorrhage before the nerves could be fairly divided, or when
they did survive the operation, it was afterwards found that the
superior filaments of the nerve were left uncut; he informs us that
he at last succeeded in performing the experiment in a satisfactory
manner upon a goat. He states that it was remarked in this experi-
ment, that, as the roots of the accessory nerves were cut, the voice?
became gradually weaker, and when the last filaments were divided
it became completely lost.t It must, however, be apparent, that
one negative experiment of this kind can never be adduced as satis-
factory evidence of the dependence of the movements of the larynx
upon the spinal accessory. There were here other causes in opera-
tion which might suspend the power of emitting sounds besides the
section of the roots of the accessory nerves, and the simultaneous
occurrence of the complete loss of voice, and the section of the last
roots of the accessory, might not have stood to each other in the
relation of cause and effect, but as a mere coincidence. The escape
of the cerebro-spinal fluid, the unavoidable loss of blood, the ex-
* Since this was written I have seen in No. iii. of Miiller's Arehives for this
year (1837.) an epitome of the investigations of Bendz, "De connexu inter ner-
vum vagum et accessor! iim." From these dissections, it is concluded (Jahres-
bericht, &c. in Jahre 1836, p. xxv.) that both in man and animals, the nervus
pharyngeus of the par vagum is derived in a great part from the filaments of the
accessory, and that the nervi laryngi, superior and inferior, and the cesophageal
plexus also receive a few filaments from this nerve. He has also observed^ the
accessory in man, (p. xxiv.) furnish a few filaments to the second: ganglion of
the par vagum. Into this second ganglion of the par vagum all the filaments of
the vagus do not enter. He has even seen in the rabbit some of the filaments of
the vagus pass the superior ganglion placed on this nerve, without entering. inlQ;,
its formation.
t Oper. eit. p. 94.
SPINAL ACCESSORY NERVE. 63
posure of the medulla oblongata to the external air, and the pro-
tracted pain and straggles of the animal, are more than enough to
induce a state of stupor and debility sufficient to suspend its cries.
In two attempts to repeat this experiment upon a dog and a cat, the
animals died from hemorrhage before the nerves could be fairly
exposed and divided. I then determined to try the effects of irri-
tating these nerves within the cranium on an animal recently killed.
I find that this method had been previously followed in one experi-
ment by MuUer.* In this experiment he ascertained that irritation
of the nerviis vagus within the cranium, both mechanically and by
a single pair of galvanic plates, produced contraction of the oesopha-
gus. As I was not aware that such an experiment had been made
until I had completed those which I am about to mention, I could
not be influenced in my observations by the authority of this very
distinguished physiologist and accurate observer. I performed my
experiments in the following manner. The animal was deprived
of sensation by a dose of prussic acid, and the cranium was then
opened as rapidly as possible. As soon as the nerves were exposed,
the parts in the neck, which it was wished to observe during the
irritation of the nerves, were quickly laid bare. The nerves were
insulated from each other, and the animal was so placed, that while
Dr. Duncan and Mr. Spence irritated the nerves, I could watch the
effects upon the parts exposed. Some of the experiments failed
from the facility wnth which these nerves are broken within the
cranium, and from the enfeebled state of the muscular contractility,
from the length of time required to go through all these preparatory
steps. We procured, however, some results which I consider suf-
ficiently satisfactory as far as they go. In one experiment, in which
the spinal accessory was irritated by galvanism, when the aperture
of the glottis was exposed, powerful convulsive movements of the
shoulder were observed, but not the slightest movements of the
muscles of WiQ glottis. In another dog convulsive movements of
the pharynx accompanied the convulsive twitches of the shoulder.
In one dog in which irritation of the spinal accessory had produced
powerful movements of the shoulder, the nerve was broken within
Xhe, foramen lacerum, on attempting the irritation after the glottis
was brought into view ; the galvanic wires were then applied to the
par vagum, and a distinct though feeble movement of the arytenoid
cartilages followed, unattended by any movements of the shoulder.
In another dog, a distinct movement of the pharynx and arytenoid
cartilages followed the pinching of the insulated par vagum with
the forceps. I attach most importance to this last experiment, as it
is difficult in some cases to be quite certain that the galvanic influ-
ence is confined to the nerve operated upon, when others are placed
in the immediate neighbourhood. From those experiments we
think there can be no doubt that the trunk of the par vagum con-
tains within it motor filaments independent of those which it re-
ceives from the internal branch of the spinal accessory. That the
internal branch of the spinal accessory assists in moving the mus-
* Handbuch, &c. Erster Band, p. 641.
64 REID ON THE EIGHTH PAIR OF NERVES.
cles of the pharynx we are satisfied, not only from the experiments
just stated, but also from those upon the pharyngeal branch of the
par vagum. Of the probable destination and functions of the other
filaments of the internal branch of the accessory, we cannot pre-
tend to judge without more extended inquiries. We certainly do
not consider that these experiments entitle us to assert that they are
not motor filaments.*
I may here state, that the arguments adduced from comparative
anatomy, in favour of the opinion, that the spinal accessory is solely
connected with the involuntary respiratory movements, may be
considered as completely controverted by late researches. Serres
has discovered its existence in some birds; Weber in some fishes;
and BischoflTin birds, fishes, and reptiles.
These experiments upon the glosso-pharyngeal and spinal acces-
sory have furnished results in direct opposition to the respiratory
system of Sir C. Bell ; for certain supposed functions of these nerves
have been considered as forming one of the principal strongholds
of that ingenious and plausible theory. I think there can be no
doubt, that the distinguished discoverer of the distinct functions of
the anterior and posterior roots of the spinal nerves, has taken a
very limited and partial view of the sympathetic movements of the
body, when he framed his respiratory system. His attention ap-
pears to have been so entirely absorbed by those connected with
the respiratory function, that he seems to have forgotten that there
are other extensive associated and sympathetic movements of the
muscles of the body, besides those which he has so beautifully illus-
trated. For it is obvious, that, if a particular tract of the spinal
chord is necessary to carr}^ on the respiratory movements, there
ought also to have been a defecatory tract, a urinary tract, and so
on, to carry on the other sympathetic movements in which a num-
ber of distant muscles are engaged in simultaneous action. If the
other associated movements can go on without it being necessary
that the nerves supplying the muscles engaged in these, should come
from particular tracts of the spinal chord, then surely there can be
no necessity for this in the case of the respiratory nerves. The
insufficiency of Sir C. Bell's theory to answer the ends proposed
has been pointed out in a most satisfactory manner by Dr. Alison in
his elaborate essay on Sympathy. t It appears to me that physiolo-
gists have been exceedingly premature in framing new systems of
nerves to carry on the sympathetic and instinctive movements of
the body. For I believe that it will be found, that all the nerves
of the body which can transmit the influence of volition can also
transmit the influence by which the muscles they supply are called
into sympathetic movement, and that the reason of some muscles
being called more frequently into sympathetic action than others,
does not arise from any difference in the nerves supplying these
* The dissection of Bendz, to which we have already referred, seem to show
that these filaments of the accessory are distributed upon the larynx and oesopha-
gus. They therefore probably assist in the movements of these parts.
f Edinburgh Medico-Chirurgical Transactions, Vol. ii.
spina;, accessory nerve. 65
muscles, but from a difference In the circumstances under which
they are placed. We term the muscles of the extremities muscles
of strictly voluntary motion, though we admit that when a person
is falling forwards, the arms are instinctively thrown in front, — in
other words, some of these muscles contract without our volition,
and through means of an influence sent along the same nerves by
which they are called into voluntary action. In the same manner,
when the foot of an infant is pricked, the leg is instinctively drawn
upwards; and the involuntary start of surprise is sufficient to show
that the respiratory are not the only muscles of the trunk which
are involuntary in their action. The respiratory muscles are said
generally to be partly voluntary and partly involuntary; but it
appears to me perfectly obvious, that they are as much muscles of
voluntary motion as those of the extremities, and that the reason of
their so frequently receiving the name of involuntary arises from
this, that, though properly voluntary, they are so much more fre-
quently called into action by impressions accompanied by sensations
than other voluntary muscles, that this has attracted the attention of
physiologists to them in particular. We have seen that the muscles
of the extremities (which every one calls muscles of strictly volun-
tary motion, to distinguish the mode by which they are stimulated
to contraction, from that of the heart and muscular coat of the intes-
tines,) perform associated movements without our volition on the
excitation of certain impressions and sensations, and they obviously
differ in no respect from the muscles of respiration, except in the
relative frequency with which those involuntary movements are
performed. This difference in the relative frequency of the action,
again, evidently depends only upon the circumstances under which
they are placed ; for it is absolutely necessary for the preservation
of the individual that the impressions arising from the want of fresh
air in the lungs be frequently and regularly repeated, while the other
sensations to which we have referred can be only occasional and
accidental. It is obvious from these remarks that we do not object
to the application of the term, muscles partly of voluntary and partly
of involuntary motion, on account of its want of corrrectness, but
because it is apt to mislead, for it may either induce us to believe
that these respiratory muscles have at times some analogy in their
mode of excitation to the heart and muscular coat of the intestines;
or, what is more likely, that there is something specifically different
between the nerves by which they are stimulated to contraction,
and those distributed upon the muscles of the extremities. We
believe that there are no muscles in the body which do not also
sometimes deserve the name of involuntary, though the relative
number of their involuntary movements may be far inferior to the
strictly voluntary. If these views be correct, there appears to be
nothing so peculiar in the action of the respiratory muscles, that they
should require any distinct set of nerves.* How, or in what manner
* I do not mean to deny, that it is possible that the motor filaments for trans-
mitting the influence of volition may be distinct from those which transmit that
m 7
Q6 REID ON THE EIGHTH PAIR OF NERVES.
the influences of volition and of certain impressions and sensations
are invariably directed along certain motor nerves in preference to
others, is at present, and probably ever will be, an utter mystery.
The ends for which these sympathetic and instinctive actions were
designed are obvious, but we have not been able to perceive any
particular structural arrangement of the nervous system specially
connected with their manifestation.
Though the sensitive and motor filaments of the spinal nerves
appear to be separate from each other, and arise from distinct tracts
of the spinal chord, yet it is not so with those arising from the
upper part of this chord ; and there appears to be some blending
together of the motor and sensitive tracts of the spinal chord, when
continued upwards into the medulla oblongata, which we cannot
at present fairly explain. To say nothing of \he, portio dura and
fourth pair, we find the glosso-pharyngeal, par vagum, and spinal
accessory arising in the same line from the middle column of the
spinal chord, and yet the filaments contained in these three nerves
are partly sensitive, and partly motor ; for no one can deny that the
muscles of the glottis can and do frequently act from volition. It
is possible that some of those motor filaments are furnished by the
band of fibres which Mr. Solly* has lately described as passing
across from the anterior column to the cms cerebelli. A good deal
evidently still requires to be done, before we can expect any satis-
factory elucidation of the anatomical arrangement of these columns of
the spinal chord, and their relations to the different nerves attached
to them. We find, for example, Bellingeri and Sir C. Bell, two of
the latest and best authorities on this subject, difier with regard to
the origin of the posterior roots of the spinal nerves ; for while
Bellingeri t describes these posterior roots as arising partly from the
posterior column, partly from the grey matter in the posterior col-
lateral groove, and partly from the middle or lateral column, Sir C.
Bell has renounced his former opinion, that they come from the
posterior column, and now describes them as arising from the middle
column.!
sympathetic influence by which muscles are called into action in obedience to
impressions made upon distant parts, and that those two sets of filaments may
be bound up intimately together in the nervous chords distributed upon the mus-
cles of the trunk and limbs. Since, however, we have no direct facts to guide
us in a speculation of this kind, it is surely worse than useless to enter upon it.
What we maintain is, that the nervous chords supplying all the muscles of
the trunk and extremities, are capable of transmitting both the influence of volition
and of sympathetic movement; and that, therefore, there is no specific difference
between the nervous filaments supplying the muscles of respiration and those of
the extremities.
* On the Human Brain, &c. f Oper. cit. p. 69.
X On the Nervous System, p. 234 and 238, edit. 3d. Sir C, however, adds in
a note, p. 234, that it is not impossible that the posterior column may be con-
nected with the sensitive root of the spinal nerves, though he has not hitherto
succeeded in tracing it.
THE END.
OBSERVATIONS
ON THE STRUCTURE HITHERTO UNKNOWN OF
THE NERVOUS SYSTEM
in-
MAN AND ANIMALS.
BY PROFESSOR EHRENBERG.
[Read to the Academy of Sciences at Berlin, Oct. 34, 1833.]
TRANSLATED WITH ADDITIONS AND NOTES,
BY DAVID CRAIGIE, M.D.
INTRODUCTION.
The microscopical discoveries of Professor Ehrenberg on the
minute structure of the brain and nerves are so important both as
anatomical facts, and as probable means of throwing light on the
functions of the nervous system, that they deserve to be fully
known to all medical readers who know that anatomy and physiology
form the laws of all correct medical knowledge. Of the present
memoir, which was first read to the Academy of Sciences at Berlin
on the 29th April 1833, an abridgment was published the same
year in the twenty-eighth volume of Poggendorff's Annalen der
Physik; and from this the short notices already circulated in various
countries have been derived. The author had soon after extended,
repeated, and verified his observations ; and in the meantime, while
his results were in several points opposed b)'^ Professor Krause,
they were confirmed by Miiller, and modified, as we have shown
in our last Number, by Joseph Berres, who is Professor not at Berlin,
as is stated in the Medical Gazette, but at Vienna. The whole of
the original memoir was only published in the Transactions of the
Berlin Academy last year [1836 ;] and attached to it is an appendix,
containing, with the information now given, several other facts in
confirmation of the accuracy and truth of the observations of the
author, and which has been rendered necessary, in consequence of
the representations of Professor Krause.
The information contained in the memoir is too important to
admit of abridgment ; and the subject is so little understood, and
requires for its correct understanding explicitness and perspicuity
so much, that I think it best to publish the memoir nearly and
essentially as it stands in the original. If it be thought that the
68 EHRENBERG ON THE BRAIN AND NERVES.
literary history which forms the first part is unnecessarily minute,
or might have been wholly spared, I may be permitted to suggest,
that the alleged discoveries which daily experience shows arise
from ignorance of the researches of previous inquirers, must be
allowed, by every candid inquirer after exact knowledge, to prove
the necessity of removing this barrier to its progress. It would be
well if the example of Professor Ehrenberg were more generally
imitated ; and on the present subject it may be observed, that what
he has thought necessary to write, is surely deserving of being
perused. It is also not only interesting, but highly instructive to
trace the resemblance between the few facts discovered by Leeu-
wenhoek, Delia Torre, Prochaska, Fontana, and those established
by the long and careful train of observations by Ehrenberg.
One omission in the history sketched by the present author, I
have observed with some surprise. Professor Ehrenberg nowhere
mentions the microscopical observations of Sir Everard Home and
his able coadjutor, Mr. Bauer ; and as these observations have
always appeared to me important,* and are valuable in several points
in which they coincide with those of the present author, I have
added a short sketch of their principal results. This task I once
imagined I might have been spared by the short account which I
gave, in 1828, of the minute structure of the brain, in my Elements
of General and Pathological Anatomy; and I would still be satisfied
by referring either to the original papers in the Philosophical
Transactions, or to the work now mentioned. The former, how-
ever, is not very accessible ; and the latter is now out of print. In
this manner the reader will be in possession of all the most import-
ant information on the minute structure of the brain, spinal chord^
and nerves. — [Translator and Editor.]
SECTION I.
^T-E /.
KiiRENBKm. — PLATE 11.
,y^^f, ?
Ehrenberg. — PL^TE ///.
Ehrenberg.— plate IF.
,v. V„..'i
a
(g) @|
EHRmBERG.—FL^TE V.
Fig. 3.
Fig. 4.
EURENBERO.—' FLjiTE VI.
fin
ON
THE COMBINATION OF MOTOR AND SENSITIVE
NERVOUS ACTIVITY;
OR,
ON THE PRODUCTION OF SENSATIONS BY MOTIONS.
BY PROFESSOR STROMEYER,
HANOVER.
TRANsiATEB TROM THE " CKottfitflisfje CSele|)rte ^njetjjen,"
With Additions communicated by the Author, by
W. LITTLE, M.D.
CHAPTER L
Marshall Hall's Theory. — The old Notions of Sympathies overthrown by Anatomy
and experimental Physiology. — Presumed connexion of the Nervus Saphenus Su-
perior with the symptoms of Coxalgia. — Case of Paralysis of Glutaei — Treatment. —
Coxalgia with Contraction of the Psose and Iliacus. — Certain Sensations produced
through the Medium of the Brain and Spinal Marrow.
Among the doctrines for which we are indebted to the discoveries
of "modern physiologists, few are so capable of exciting the universal
interest of medical practitioners as the theory announced by Dr.
Marshall Hall — namely, that the motions which arise through exci-
tation of the sensitive nerves, are not the result of direct connexions
of motor and sensitive nerves, but arise through the medium of the
central organs of the nervous system. Besides the evidence from
the experiments brought forward by the illustrious English phy-
siologist, the truth of his theory has been admitted with the less
difficulty, owing to the conviction obtained by tracing the primitive
fibres of the nerves — that their apparent connexions consist only of
juxta-positions.
Anatomy and experimental physiology have thus mutually assist-
ed one another in overthrowing the old notions of the sympathies.
When we regard, however, the brain and spinal marrow as the
mediators between sensations and their resulting motions, we might
be led to believe that the doctrine of reflection can be of little
utility to pathology, because it might be supposed that each nerve
of sensation is connected with every motor nerve. But experience
teaches us that local excitement is followed by universal reaction in
states of highly augmented sensibility of the nervous system only —
for example, tetanus after a slight wound ; and that under the ordi-
m 12
116 STROMEYER ON THE PRODUCTION OF SENSATION.
through the action of the glutaei. The muscles of the entire limb
had increased in bulk, yet they did not fully obey the direction of
the will ; for in attempts to tread upon the right (the injured) foot,
the sole had not the sensation of touching the ground. Neverthe-
less, frequent formications, and slight startings of the entire limb,
indicated the probably speedy and complete restoration of the
voluntary motion. The patient had, it is worthy of remark, the
same sensations in the sole of the foot, and in the whole of the limb,
when they were touched, as in the sound side : if she, however, did
not feel the treading upon the ground, the sole of the foot was only
deficient in that peculiar innervation of the cutaneous nerves, which,
according to my theory, is the attendant and consequence of volun-
tary muscular exertion.
There is another case possible, in which contraction of the psoas
and iliacus might arise, — their paralysis on one side. Experience
will teach us whether this state of things also would produce pain
in the (opposite) knee ; it appears to me, however, more probable,
that pain would be felt at some other spot of the affected or paralyzed
side ; for the innervation of the two extremities is, upon the whole,
so separate, and the nervous activity, therefore, in perfect equipoise,
that it would not so essentially increase in the psose of the sound
side, so as to produce their contraction and consequent pain in the
knee on that side, which would be the case if cause and effect
resided in the same side of the body, as in the above related case.
I have recently met with another case, which in a very interesting
manner illustrates this point. It is that of a tall spare youth, afiected
with coxalgia, presenting the flexion of the thigh, and pain at the
knee, from the contraction of the psose and iliacus. This youth's
leanness and flaccidity of tissue enabled me to feel the tendon of the
psoas and iliacus at its insertion into the lesser trochanter. Each
time that I touched, or slightly pressed, the tendon of the muscles,
he complained of increase of pain in his knee.
If the proposition were fully demonstrated, that immoderate con-
tractions of the psose and iliacus internus, or of the psose alone, can
induce pain at the knee, we must deduce the very interesting conclu-
sion, that the excitation of motor nerves produces simultaneous excita-
tion of sensitive nerves; or that through excess of voluntary or invol-
untary motion, pain isfelt in filaments of sensitive nerves not distributed
to the muscles themselves which are in action. We might atfirst sight
be inclined to explain the connexion of contraction of the psose with
pain in the knee, by mechanical compression ; but, setting aside that
purely mechanical explanations of pathological phenomena seldom
deserve much confidence, there are other cogent objections. In fact,
we cannot conceive the occurrenceof compressionof thenervus saphe-
nus superior by flexion of the femur ; it would be much more likely
to occur during extension. But it is well known, that in coxalgia
the pain in the knee becomes constantly more severe, in proportion
to the increase of the flexion of the thigh ; whereas the flexion must
diminish the pain, if it depended upon compression of the nerve.
Nor can we suppose the existence of an inflammation of the nervus
SENSATIONS THROUGH THE MEDIUM OF THE BRAIN. 117
saphenus superior ; at any rate not in those cases in which contrac-
tion of the psose and iliacus, with pain of the knee, results from pa-
ralysis of the antagonists of those muscles. We find ourselves, there-
fore obliged to admit a more dynamic cause of the knee pain. This
consideration leads very easily to the supposition that the increased
innervation of those muscles which are urged to too constant con-
traction, produces an increased centripetal streaming (of the nervous
matter or principle) in those nerves of sensation more immediately
connected with the motor nerves of the muscles.
As therefore according to the doctrine of reflex motions after sen-
sations, it is believed that, through the intermedium of the brain
and spinal m.arrow, certain motions follow certain sensations, in like
manner the abstract of my new theory is, " that certain motions
produce certain sensations through the intermedium of the brain
and spinal marrow.'^ Those physiologists who but recently have
conceded the truth of the doctrine of reflexion, will, at first view,
find this new idea very repugnant, as it seems to imply that centri-
petal currents can take place in the motor nerves, and centrifugal
in those of sensation ; which would be in opposition to all experience
and innumerable experiments. It depends, however, only upon the
nature of our conception of the manner in which the various roots
of the motor and sensitive nerves are excited. Precisely as in ac-
celeration of the arterial stream of blood the current in the veins
must be hastened, is it in the case of the nerves. As the heart acts
propulsively upon the arterial blood, and attractively upon the venous,
in like manner a similar principle may be in operation in the cur-
rents of the nervous fluid ; the activity of which principle can never
be increased in one direction only, but simultaneously excites in-
creased motions both in the sensitive and motor nerves. I do not
mean to say, however, that I consider the motion in the nerves
circulatory, for anatomy hitherto does not support the direct con-
nexion of the filaments of nerves of diflferent nature at their peripheral
extremities, and the example of pain in the knee, from contraction
of psose, is much opposed to it, as we cannot conceive a circulation
between the motor filaments ramified in those muscles and the sen-
sitive filaments distributed about the knee. But if we compare the
connected motor and sensitive nerves to a line passing over a pulley
and supporting at each end an equal weight, and regard the pulley
as the point in the central organs where the two nerves act upon
one another, we may conceive that, as any tension exercised upon
one point of the line will set it into motion throughout its whole
length, in the same way centrifugal currents of the motor nerves
will excite centripetal currents of the sensitive nerves, and, vice versa,
centripetal currents of the sensitive will induce centrifugal of those
of motion.
If my theorum be proved to be correct, Marshall Hall's expression,
"reflexion" indicative of the reaction of motor nerves uponexcitation
of those of sensation, howeverappropriate it appears to be at first view,
will be inapplicable ; as it, according to the recognised laws of the
12*
118 STROMEYER ON THE PRODUCTION OF SENSATION.
transmission of the nervous principle in motor and sensitive nerves,
appears to exclude the reflex operation of motor upon sensitive
nerves.
We shall have considerable hesitation in readopting the vague
term sympathy for these reactions, as it reminds us too strongly
of the nervus sympathicus, through the agency of which these
phenomena were sought to be explained formerly. Until some one
conceives a more explicit expression, to indicate the reciprocal
operation of motor and sensitive nerves through the medium of the
central organs, I propose the term combination of motor and sen-
sitive nervous activity. It has the advantage of defining no par-
ticular idea concerning the nature of the nervous currents, and
therefore no false notions can be induced. I can almost believe that
a too definite idea of the kind I allude to hovered in the mind of
the English physiologist (Marshall Hall), or he would probably have
been led to the investigations which I now introduce to the public.
Should my theorem be adjudged correct, it will prove that our in-
ductive knowledge arising out of the elaboration of the physical
laws of the nervous system, is not yet so far advanced as Johannes
Mueller appears to think ; and that independent of the known laws
of nervous activity, a wide field remains open to the spirit of
observation.
It would be very difficult to demonstrate, by experiments upon
animals, the truth of the proposition that every motion is followed
by certain sensations, because we cannot jf?grceiwe sensations, in brute
creatures, as we can motions. I am, therefore, convinced that human
physiology will in time afford the most satisfactory confirmation of
this doctrine, as man alone is able to express himself clearly with
respect to his sensations.
CHAPTER II.
Vision — Voluntary power over the Iris — Explanation — Susceptibility of the Retina
to impressions increased in the ratio of the number and irritability of Ocular Muscles
in action — Squinting — Club-foot — Cause of scrofulous intolerance of light — Reaction
of the Portio Dura upon the Optic Nerve — Audition — Utility of the Muscles of the
Ear — Connexion of the Portio Dura with the Auditory Nerve — Taste — Effects of
Galvanism — Functions of the different Nerves distributed to the Tongue — Olfaction
— Connexion with the Respiratory Nerves.
Hitherto I have only briefly propounded my theory that certain
motions or contractions produce certain sensations, through the
intermediuTn of the brain and spinal marrow — the complement
to the reflection of Marshall Hall. I have related the circumstances
which led first to this investigation, and have shown how we may
remove the difficulty of understanding the existence of apparently
centripetal functions in the motor and centrifugal in the sensitive
nerves.*
* Without going into the consideration of the accuracy of Stromeyer's views,
the confirmation or refutation of which will be best effected by observation, it
VISION. 119
As the nerves of the senses present an antithesis to the motor
nerves, similar to that evinced by the ordinary sensitive nerves,
and the augmentation of their excitability being accompanied by
peculiar phenomena, it naturally followed that I should at once
direct my attention to them, in order to search for proofs of my
theory.
Vision. — Modern Physiologists were almost unanimously of
opinion that the movements of the iris depended upon the irrita-
bility of the retina, and that light exercises no direct influence upon
that organ. If the iris act, when touched by the cataract needle, even
after dilatation by belladonna, it only participates with all motor
organs in the property of contracting when exposed to mechanical
stimulus. Thus the pupil has hitherto been considered as the baro-
meter of the excitability of the retina, and of its reaction upon the
stimulus of light.
The celebrated Professor J. Mueller* has lately attempted to
shake this opinion, by endeavouring to prove that the will can act
upon the pupil independently of the co-operation of the retina.
Thus he has observed, that by shutting one eye and turning the
other as much towards the nose as possible, the pupil is lessened ;
and that it is dilated, on the contrary, if the eye be directed to the
opposite side — outwards. The diminution of the pupil is greatest
when the axes of both eyes are made to converge as strongly as
possible. If one eye be directed outwards, and the other inwards
may be remarked, that although apparently opposed to our present knowledge of the
manner in which the nervous principle is communicated along motor and sensitive
nerves, whether that be by currents, vibration, &c., the phenomena of the production
of sensations by the contraction of muscular fibre, if they really take place, may
be explained without violating any of the physiology of the nervous system : nay,
in accordance with it, for as the phenomena of health and disease prove to us
the accuracy of reflex motions after irritation, with or without sensation, of cer-
tain sentient nerves, and the consequently intimate connexion of the origin of
the sensitive and motor filaments in the central organs, we may conceive that as
centripetal currents in the sensitive filaments produce, under certain circumstances
such an alteration or affection of that part of the central organ where they are
connected with the motor filaments, as to induce centrifugal currents or a vibra-
tion in those motor filaments, — or, in other words, induce contraction of certain mus-
cular fibres, — in like manner, it is not impossible that whilst what we mean by
centrifugal currents is going on in the motor filaments, such an alteration or
affection of that part, the connecting link, in the central organs where the motor
and sensitive filaments meet, occurs as to cause either increased susceptibility
to impression, or sensibility of that part, amounting even to the feeling of pain
by the individual. It is not necessary that propagation of any thing or kind,
tension or vibration, take place along the sensitive nerve to the spot in which the
pain is felt — we know that that cannot be : the individual imagines that he feels
pain in a certain part (say the knee for example, according to Stromeyer's expla-
nation of the knee-pain in coxalgia, to which the peripheral extremity of the
nerve is distributed, precisely as when we strike the ulnar nerve at the elbow,
pain is felt along the whole course of the limb, below the seat of injury supplied
by that nerve; or when the nerve of a stump is irritated, the patient feels an
injury to his toe, &c. This is the rationale of the hysteric and other pains said
to exist only in the mind of the patient. The pains really exist, although not felt
at the part where the cause exists, but imagined to be felt elsewhere. — W. J. L.
* Handbuch der Physiologic, p. 764.
120 STROMEYER ON THE PRODUCTION OF SENSATION.
no perceptible alteration of the pupils takes place. The pupil is
narrowed when we turn the eye upwards and inwards — that is,
when we set the inferior oblique muscle into action.* The more
parallel the globes are, the wider are pupils.
Professor Mueller explains the diminishino; of the pupil, during
the motions of the eye-ball, effected by the musculus rectus internus
and obliquus inferior, through the circumstance of those muscles
being supplied by the oculo-motorius nerve, which regulates also
the motions of the pupil, whilst the external rectus muscle, which
draws the eye outwards, is supplied by the nervus abducens. So
that (according to Mueller) at the same time that the will acts upon
the muscles which receive filaments from the oculo-motorius, its
influence is extended to the iris, which is not the case during motions
of the rectus externus muscle.
The facts observed by Mueller are perfectly correct, although
his explanation is erroneous, which is easily shown. Thus the leva-
tor palpebrse superioris is likewise supplied by the oculo-motorius ;
nevertheless the pupil becomes very large when the eye is opened
very widely voluntarily. The narrowing of the pupil during con-
traction of the rectus internus and obliquus inferior muscles must
therefore proceed from some other cause than the influence of the
will upon the oculo-motorius nerve; for we cannot assume one law
for one branch of a nerve, and not apply the same law to all the
branches. Again, it is found that light has so much influence upon
the narrowing of the pupil in Mueller's experiments, that it can
scarcely be observed during twilight ; whereas the dilatation of the
pupil during abduction is at that time very considerable. Much
depends, also, whether the eyes be fixed upon an object or not. In
the former case the pupil is constantly narrower. None of these
variations could occur if the motions of the pupils were at all
voluntary.
The old doctrine of the dependence of the motions of the iris
upon the stimulus of light is therefore not yet shaken, and we may
continue to regard the pupil as a measure of the excitability of the
optic nerve, if we give a different explanation of Mueller's experi-
ments. It is now well known that a stimulus applied to the eye-lids
makes the eye intolerant of light, and causes contraction of the pupil ;
hence no ophthalmic surgeon introduces Pellier's cataract hooks be-
neath the eye-lids, but inserts them in a fold of the skin of the upper
eye-lid, at the margin of the tarsus. Many surgeons believe even
that to be prejudicial, and prefer that the upper eye-lid be held by
an expert assistant, by pressing its cilia with the tips of the fingers
against the orbital arch of the frontal bone. This well known fact
led me to perform the following experiment.
I caused both eye-lids of a pigeon to be firmly held apart with
* This voluntary power of the inferior oblique, mentioned by Professor Mueller
is in opposition to the experiment of Sir Charles Bell, where he divided the
obliquus inferior and superior of the eye of an ape, and nevertheless all the
accustomed motions of the eye continued.
VISION. 121
two forceps, by assistants. The bird drew its membrana nictitans
across the eye, the pupil contracting slightly at the same time. The
bird, nevertheless, made no attempts to close the eye-lids, which
were still held asunder, probably because it was conscious that they
were fully in the power of the forceps, and because the movements
of the membrana nictitans sufficed its purpose. I then seized the
membrana nictitans with Baeer's hook, and drew it completely back,
so thattheanimal could notmove it; during thattimethe pupil wasnot
altered. But as soon as I loosened a little my grasp with the hook,
so that the bird perceived that it could again somewhat employ its
membrana nictitans, it drew it vigorously forwards, and simul-
taneously the pupil contracted very considerably. The animal's
attempts to close the membrana nictitans coincided completely with
the narrowing of the pupil ; and when I resumed the mastery over
the membrane by means of the hook, the contraction of the pupil
immediately ceased. The same result was obtained in repetitions
of the experiment.
Now the membrana nictitans is supplied by the abducent nerve ;
so that the question of the direct translation of volition to the iris
cannot here be mooted, for the iris receives no nerve from the abdu-
cens. The irritation of the sensitive nerve of the eye-lids and mem-
brana nictitans, derived from the fifth pair, could not be the cause
of the periodical narrowing of the pupil, or this would have taken
place instantly, whereas it only occurred during the voluntary
attempts of the animal. It is also known that excitement of the fifth
pair does not cause the pupil to contract. Again, in the operation
for cataract, the pupil does not contract unless the operator incau-
tiously touches the iris ; and even the most unsteady eye, and most
intolerant of light, becomes quite quiet when the puncture has been
made, and the patient is conscious that the eye is in the power of
the operator. Every attempt at motion immediately ceases, and
the eye follows, independent of the will every movement of the
needle. Thus in order to remove foreign particles from the cornea,
the conjunctiva of the globe may be seized with forceps. If this be
done with dexterity, the eye is rendered quite quiet — is not even
suffused with tears, and the pupil does not contract ; this I have
often observed in Graef's clinique, at Berlin. The irritation of
the nerves of sensation of the eye do not, therefore, make it intol-
erant of light ; but the attempts to move it increase the irritability
of the retina.
Mueller'sexplanation of his own experiments is therefore i ncorrect ;
as the exerting of the membrana nictitans, the muscles of which
receive their nervous power from the abducens, induce contraction
of the pupil, exactly the same as the action of those muscles which
are supplied by the oculo-motorius. The objection may be made
that the pigeon, during the motion of the membrana nictitans, may
have directed the globe inwards and upvvards, through the action
of some of the muscles supplied by the oculo-motorius ; but had that
motion taken place it must have been perceived, as the animal was
122 STROMEYER ON THE PRODUCTION OF SENSATION.
not prevented from moving it through the holding of the membrana
nictitans. The contraction of the pupil occured only when the
animal was exerting the membrana nictitans, and neither before nor
afterwards.
Besides it is not difficult to state the reason why, in man, the
pupil contracts during motions of the eye inwards. The irritability
of the muscles supplied by the oculo-motorius is evidently greater
than that of those supplied by the trochlearis and abducens. As
for perfect vision both eyes must be employed, their converging
motions are the most frequent and lasting ; so that this increased
power of the muscles which direct the eye inwards is as useful as
necessary. Abductionof theeyeis,onthe contrary, seldom required ;
for, in order to see distinctly, we turn the head towards the object
if it lie to one side. This is immediately succeeded by a consider-
able converging of the axes of both eyes. I have no doubt, there-
fore, that the changes of the pupil during motions of the eyes will
be found to vary in diflferent men according to the nature of their
daily avocations. It is not remarkable, therefore, if a literary man,
like Professor Mueller, who is constantly occupied in the minutest
researches, shows by adduction of the eye, a very narrow pupil.
His daily avocations require a constant converging of the eyes, by
which the irritability of the abducens must be much diminished.
There can be no doubt that in peasants, for instance, the relation of
the various motions of the eyes is quite the contrary. Experiments
should, therefore, be instituted in persons who have lost an eye in
early youth.* According to my views therefore, the pupil dilates
during abduction through diminished irritability of the musculus
abducens. The diminished muscular exertion excites through com-
bination of motor and sensitive nervous activity, a diminished excite-
ment of the retina. The impression of light is also felt more feebly,
and the pupil is widened.
It is likewise not difficult to explain the dilatation of the pupil
during wide opening of the eye-lids. The lower eye-lid has no
depressor muscle; but in opening the eye, the obliquus superior
thrusts the globe a little forwards, out of the orbit, b)?- which the
lower eye-lid is depressed. If the levator palpebrse superioris and
the obliquus superior be extraordinarily exerted, the remaining
muscles of the eye must be inactive, to allow the eye to project
from the orbit. As during this act only a few muscles are in
activity, we may conceive that the excitement of the retina is much
less than when all the muscles of the orbit are in a moderate degree
of activity. Thus, in powerful voluntary stretching open of the
eye-lids, the sensibility to visual impressions, even in' a moderate
light, is much weakened, the person sees indistinctly ; and it is well
known that many men can, by powerfully forcing their eyes open,
*It is interesting to be able to add, that Professor Krause, of Hanover, has
informed me that he has examined a person who lost one eye in early youth.
His examination of this individual confirms my opinion ; for in this case the
pupil became as narrovir during abduction as adduction.
VISION. 123
look at the sun's disk at midday, whilst they are unable to do it
with their eyes half closed. A further indication of the feeble in-
fluence of the will upon the musculus abducens is the fact, that few
persons are able to abduct simultaneously both eyes, whereas every
body can readily perform converging motions. As we commonly
perceive in new-born children a squinting-like irregular movement
of the eyes, it is probable that the habit of fixing them upon objects
brings on a certain relation in the irritability of the muscles of the
eye, by which the adductors obtain the ascendancy. Squinting
itself affords an interesting contribution to my notion, that the
sensibility of the retina is connected with the activity of the orbital
muscles. Squinting is in most cases evidently the result of spasm
of single muscles of the eye, and most frequently of those supplied
by the oculo-motorius, in which, in the normal state also, the irrita-
bility is greater than in their antagonists. Through the same cause
one form of club-foot (Talipes varus) is by far more frequent than
the contrary deformity (Talipes valgus), because the muscles of the
calf and the tibialis posticus are, in health, stronger than their an-
tagonists. Such squinting eyes are always in the highest degree
intolerant of light when being employed in vision, and the patient
tries to direct them to an object ; so much so, that when we bind
up the sound eye, the affected one is filled with tears, — appears to
be suffused in an ocean of light, and the pupil at the same time
contracts. If the binding up of the sound eye be at first too long
persisted in, the patients get giddiness, head-ache, and even vomit-
ing : we are, therefore, obliged to increase gradually the duration
of the binding up of the eye, to escape these effects of a too highly
excited sensibility of the retina. This is a striking example of the
combination of motor and sensitive nervous activity in their excess,
in the form of spasm and hypersesthesia, which, in a nerve of sensa-
tion, would be called neuralgia. I do not imagine that ophthalmo-
logists will in this case be uncertain from whence the first impulse be
given — whether from the motor or from the sensitive nerves.
Squinting has ever been looked upon as an affection of the muscles.
A similar connexion between an affection of muscles and hyper-
sesthesia of the retina exists in strumous ophthalmia. There are
few ophthalmic diseases in which the intolerance of light is greater
than in this; and yet the organic alterations which scrofulous
inflammation of the eye depends upon lie in the eye-lids alone, for
the deeper parts of the ball do not in the least participate in the
affection. After years' duration only of intolerance of light, do we
witness the cessation of this inflammation often without leaving any
thing more behind than a few superficial opacities of the cornea, —
never amaurosis, as we should expect if the intolerance of light
depended on any other than dynamic circumstances. Surgeons
have been hitherto unable to explain this singular intolerance of
light satisfactorily. The above-related experiment upon the pigeon
gives the key to its solution. If irritation of the muscles of the
palpebrse produce violent contractions, make the retina more sensi-
124 STROMEYER ON THE PRODUCTION OF SENSATION.
tive and lessen the pupil, it follows, that in tonic spasm, a cramp of
the palpebrse, such as occurs in strumous ophthalmia, the sensibility
of the retina must be increased to the utmost possible extent.
It is not a subject for investigation here, whether this cramp or
constant contraction of the eye-lids arises from deposition of scrofu-
lous tubercular matter in the glands of the palpebrae, and the con-
sequent irritation of the orbicularis; — appearances teach us that
cramp and intolerance of light constantly co-exist until the material
cause be removed. Nobody can in the present case doubt from
whence the first impulse be given — whether from the motor or
the sensitive nerves: all the circumstances indicate too clearly that
the irritation commences in the palpebrse. When once the axiom
of the reflex operation of motor nerves upon nerves of sensation be
recognized, it will be readily applied to the portio dura — the motor
nerve of the orbicularis palpebrarum — and the optic nerve; because
the reaction of the eye-lids, through visual impressions, threatening
danger to the eye, are so readily observable. If this power of
prompt contraction of the palpebrse, under such circumstances, be
given to the eye as a protection, the reaction of the portio dura
upon the optic nerves is certainly not without physiological im-
portance, and the nocturnal action of the orbicularis (for as such its
contraction during sleep must be considered) contributes, probably,
to restore to the retina, by means of gentle currents of the nervous
principle to it, the sensibility which has been exhausted by the
day's continued excitement : for it is not absolute repose, but the
persistence of gentle vital stimuli, which restores depressed sensi-
bility. Thus, in paralysis of the bladder, the surgeon does not
allow the urine to flow away continually, but only from time to
time; in order that the fluid, by its constant stimulus, may assist in
restoring the excitability of the bladder. It is known that in many
persons the nocturnal contraction of the eye-lids assumes a spasmodic
character, and that on awaking in the morning, a quarter of an hour
elapses before they, by long rubbing, can open their eyes properly.
Indeed, I have met with individuals with slight inflammation of the
palpebral margins, who, when awakened in the middle of the night,
could see little or nothing for half an hour, through intolerance of
light and spasm of the eye-lids. This excess of nervous activity at
night must necessarily depend upon the physiological relations of
the eyes and their auxiliary organs.
From the above physiological and pathological data, I deduce the
following conclusions: — The excitability of the retina is intimately
connected with the irritability of the muscles of the eye. In pro-
portion as the latter is manifested {i. e. by their contraction), the
excitability of the retina is augmented. It is, therefore, extremely
probable that the muscles of the eye possess not merely the me-
chanical purpose of giving the eye the most advantageous direction
in an optical point of view, but that they also, according to the
extent of their contraction, serve to induce those exact gradations
of sensibility of the retina, which are precisely requisite, according
VISION. 125
to the distance and illumination of the object. The narrowing of
the pupil whenever the eye is powerfully exerted, to obtain perfect
vision of an object, fully agrees with my ideas, whether we regard
the object fixedly with one or with both eyes, or whether, in short,
the eyes converge, or one eye be closed, so that vision be effected
more during abduction. If, therefore, an eye-ball totally void of
appropriate muscles, were susceptible of visional impressions, it
would, at all events, be incapable of distinct perception of an object ;
as, for that purpose, the necessary augmentation of the sensibility
of the retina, which depends upon muscular contractions, would be
wanting. When we, therefore, desire to convert the imperfect im-
pression of any object lying within the field of our vision into a more
perfect one, so as, in short, to fix our attention upon it, the following
chain of events ensues: — Our power of volition excites those in-
creased currents in the motor nerves which are essential for the pro-
duction of the corresponding centripetal currents from the retina to
the brain, and which are indispensable for clear perception of the
object. The so-called motus oculi interni, concerning which so
much has been written, without inculcating any clear notion on the
subject, are probably limited in man to these gradations of the
sensibility of the retina which depend upon the will. If these in-
ternal motions of the eyes really take place in many animals — for
instance, in birds of prey, it may be presumed that in the majority
of fishes the muscular apparatus of their immovable eyes is confined
in its operation to the influence which it exerts upon the irritability
of the retina. This influence of the ocular muscles is the more
necessary in fishes, as in them the portio dura is wanting. Short-
sighted individuals, it is well known, have the habit of semi-closing
their eye-lids when they desire to see any thing accurately. This
habit has been considered quite useless. In like manner physi-
ologists in general are disposed to explain away many phenomena
as accidental, if the causes be not quite clear to them. The con-
nexion of the portio dura, as motor nerve of the orbicularis
palpebrarum, with the retina, perfectly explains that daily observable
fact; the contraction of the orbicularis, therefore, assists the other
muscles of the eye in rendering the retina more sensible.
It constitutes a singular want of harmony between physiology and
pathology, that practitioners of all shades of opinion descant about
augmentation of sensibility, without their having any generally
received comprehension of its causes — whether it depend alone upon
morbid or diseased excitement, or whether it be a process of the
normal state, or occur even voluntarily. Physiologists are more to
blame for this uncertainty than practitioners ; for the former should
direct their investigations more towards pathology instead of neg-
lecting that science for the too exclusive cultivation of the neverthe-
less highly necessary experimental physiology and comparative
anatomy. Physiological labours would thereby acquire a more
universal interest for the professional public; whereas they at pre-
sent frequently excite a painful perusal, through the numerous rela-
m 13
126 STROMEYER ON THE PRODUCTION OF SENSATION.
tions of tormenting vivisections. The researches of the English
physiologists are, in this respect, far preferable to those of their
German rivals, probably because the former, unlike my countrymen,
do not entirely withdraw themselves from practice for the sole pro-
secution of their physiological studies. These latter should bear in
in mind, that many of the greatest physiological discoveries have
been made by practising physicians and surgeons.
Audition. — The organ of hearing is furnished, in many animals,
with an important muscular apparatus, which according to our for-
mer notions, effects merely the easily conceivable purpose of pro-
ducing those mechanical alterations necessary in conformity with
the laws of acoustics, to direct the ear towards the spot from whence
the sound emanates. This muscular apparatus is perfected in pro-
portion to the difficulty with which the animal's head can be moved
in all directions. With equal design, muscles of the ear are wanting
in most birds, being replaced, in that class of animals, by the great
moveability of the head. The human ear is provided with a con-
siderable number of muscles, but if we occasionally observe an in-
dividual who is able to move voluntarily the muscles of his ears,
the instance must be regarded as an exception to the general rule ;
for man, in order to hear correctly, must direct one side of his head
to the place from whence the sound comes. When the exception
even exists, no mechanical advantange is obtain by it, nor do the
subjects of it move their ears when they listen attentively. It would
be a ridiculous assertion to maintain that nature made these mus-
cles for mere amusement : such freaks must be least sought for in
the masterpiece of the creation — man.
Nature, in my opinion, has supplied the human ear with external
muscles, in order to send to them a certain number of filaments
of motor nerves, by acting upon which we keep the auditory mus-
cles in a state of tension, although no motion of the concha is effected,
and are thus enabled to augment voluntarily the centripetal currents
of the acoustic nerve. An additional object, undoubtedly, is, that
these muscles shall support the ear in its appropriate position and
state of extension ; thus they are so arranged as to antagonise
one another in their actions, when exerted simultaneously. Obser-
vation confirms this opinion, for we may clip the ears of dogs with-
out perceptibly injuring the acuteness of their hearing. When their
attention is excited, they move the small stump which remains, and
attain in that way the main purpose of the muscular apparatus —
the acceleration of the currents of the nervus acusticus to the brain.
If we compare the large muscular apparatus of the eye with that
of the ear, we must conclude that the small muscles destined to move
the ossicula auditus and tympanum can scarcely suffice to increase
the irritability of the auditory nerve ; we must, therefore, attribute
to the muscles of the external ear a participation of the same function.
It is well known that the external auditory muscles are partly sup-
plied by the portio dura, and the connexion of this nerve with
audition is altogether so great, that the expression of the countenance
AUDITION.— TASTE. 127
alone betrays hard-hearing people, owing to the peculiar effect of
the action of the muscles of the face. Violent exertions of every
kind show themselves in the features ; and it is proverbial that
impending danger sharpens the senses. The apparently useless
consentaneous action of the facial muscles during extraordinary exer-
tions may be thus not without utility, if the excitement or calling
into operation of the functions of the portio dura be capable of aug-
menting the sensibility of the retina and the nervus acusticus.
The rheumatic, which is one of the most frequent forms of deaf-
ness, has hitherto been attributed to inflammation of the internal
ear and its consequences. Rheumatism of the ear, which specially
affects, here as elsewhere, muscular and tendinous parts, appears to
me, in many respects, comparable to rheumatico-catarrhal ophthalmia.
That disease presents great intolerance of light, although the external
parts of the eye are alone affected. Rheumatic excitement of the
muscles of the ear produces at first hypersesthesia of the auditory
nerve, humming and tingling in the ears, and after frequent repeti-
tions of the rheumatic affection, exhaustion, and torpor of the nerves.
This idea cannot remain without interest in practice, as it teaches
us, in the treatment of some affections of audition, that in order to
act upon the nervus acusticus we must apply our therapeutics to the
muscles supplied by the ramifications of the portio dura and auricu-
laris magnus nerves ; it explains the operation of many remedies,
for instance steaming and fomentations, the resting the head upon
pillows stuffed with certain herbs, a means frequently adopted, and
probably even the utility of galvanism, &c.
Taste. — Motions of the tongue are indispensably requisite for
the perfect preception of the taste of fluid ingredients. We are not
usually sensible of the sapor of our saliva, but by a few movements
of our tongue we obtain the taste of it immediately, even when we
avoid touching any part of the oral cavity with the tongue, so that
the question cannot be raised, whether it be not by rubbing in of
the sapid body, or mechanical excitement of the papillas of the nerves,
through which the more perfect perception of the taste might be
explained. The taste of a fluid, weak tea, for instance, is not per-
ceived as long as it is retained in the mouth quite at rest, nor when
the fluid first touches the tongue, if we at the same time exert our
power of holding the organ perfectly quiet. It is only during or
after movement of the tongue that we can taste. It is true that with
acrid ingredients it is otherwise, but when testing the susceptibility
of the gustatory nerve, we ought not to institute experiments with
colocynth, or with oil of vitriol, as some have done. The efibct of
galvanism upon the tongue is, perhaps, hei-e worthy of mention.
We know that it induces an acid taste ; this depends upon the gal-
vanism exciting the motor nerves of the tongue, and inducing,
therefore, hypersesthesia of the gustatory nerve, in consequence of
which the saliva appears to be sour. For correct gustatory impres-
sions, the sapid substance must not be kept constantly in immediate
contact with the tongue ; fluids are, therefore, for the most part mixed
with air, which enables us to taste them better. The contradictory
12S STROMEYER ON THE PRODUCTION OF SENSATION.
nature of the opinions of physiologists, concerning the functions of
the different nerves of the tongue is very remarkable ; but the want
of unanin:iity appears to me to afford the proof of the important
reactions which the various nerves of the tongue exercise upon one
another. The investigations of Panizza, of Pavia (Med. Gazette,
Sept. 1835, p. 848), show positively that the nervus hypoglossus is
the nerve o( motion, the lingualis the nerve oi common sensation,
and the glosso-pharyngeus the nerve of the sense of taste. The
following is, in my opinion: the reaction of these three nerves upon
one another, the lingualis, as the nerve of common sensation, gives
information of the presence of the substance to be tasted, directs the
attention of the tongue to it, or, physiologically speaking, according
to the theory of the reflex functions of the nerves, increases the
activity of the motor nerve by reflexion from the sensitive nerve ;
the excitation of the motor nerve and consequent contraction of the
muscles of the tongue, augments* the centripetal currents of the
true gustatory, the glosso-pharyngeal nerve, by which the propaga-
tion of the impression of taste to the brain ensues. If either of these
three agents, the lingual, the hypoglossal, or the glosso-pharyngeal
nerves, be deficient in their functions, the sense of taste must be
proportionally injured.
The experiments which have been instituted to ascertain the
function of those nerves have been usually too coarse. Persons
have been satisfied if salt or colocynth have been recognised.
Precisely as a difference exists between perception of light and
vision, is there also a difference between tasting, and the tasting of
colocynth.
CHAPTER II.
Olfaction — Connexion with the Respiratory Nerves — Perfectness of, dependent upon
Action of Muscles — Influence of the Trigeminus — Compound Nature of Olfactory
Sensations — Touch — Its accuracy depends upon Action of Muscles — Cause of the
Pain of Fatigue in the Limbs, and increased action of the Heart, in walking — Use
of the Muscles of the Clitoris, and of the Rrector Penis and Accelerator Urinse —
Priapism — Action of Detrusor Urinse — Modus operandi of Homoepathic Remedies —
Nature of the Pains of Delivery — Neuralgia, connected with increased Activity of
Motor Organs — Irritable Testis caused by spasmodic Contraction of the muscular
Fibres of the Inguinal Canal — Conclusions.
Olfaction. — The susceptibility of the nervus olfactorius to odours
is so intimately connected with the functions of the respiratory
nerves, that it must excite surprise that this circumstance has not
yet attracted the attention of physiologists. It appears that the
perception of the finer odours takes place only during inspiration,
* Can it augment the centripetal currents of the true gustatory"? It may pos-
sibly augment the susceptibility of that part of the central organ where the im-
pression is received. — W. J. L.
OLFACTION. 129
and without inspiration many powerful and volatile odoriferous
materials are not smelt at all.
If we hold a handkerchief sprinkled with eau de Cologne imme-
diately under the nose, we do not perceive the odour of it until we
inspire, although the volatile parts of the eau de Cologne have long
diffused themselves in the nostrils. When we hold our breath also,
we cease to smell. If we lay a pinch of highly-scented snuff upon the
floor of the nostrils, by means of a director or any other contrivance,
we can perceive its odour for a long time, during each inspiration,
but not during the intervals. The explanation of these facts has
hitherto been thought very simple ; for it was said, that the current
of air reaches the upper parts of the nasal cavities only during in-
spiration, although the anatomical form of the nostrils makes it by
no means intelligible that the current of air follows an essentially
different direction during expiration than during inspiration. This
assumption, I admit, may not be quite void of accuracy, but it does
not explain why olfaction entirely ceases during expiration, the
more particularly as we can, when expiring, direct the current of
air upwards — as, for example, in blowing the nose — without af-
fecting the olfactory nerves. At all event, currents of air through
the nostrils are required for the perception of odours. If odoriferous
materials be placed in the nose, the nostrils be held closed, and
breathing be carried on by the mouth, no smelling takes place.
Currents mechanically effected do not, nevertheless, suffice to excite
the olfactory nerves. If we pour some eau de Cologne, or a portion
of any odoriferous material, into a pair of bellows filled with air,
and then inject the air into the nostrils, it is certainly found that a
perception of some odorous matter ensues, but the sensation is not
sufficiently distinct to enable the subject of the experiment to say
positively what he smells ; whereas, on the contrary, the least
inspiratory effort on his part makes him perfectly conscious of its
nature.
Experiments should be performed for the elucidation of this
matter, which is by no means exhausted, upon persons who have
received a wound of the trachea, through which they breathe ; and
I should consider the correctness of the assertion — that the respi-
ratory nerves by their activity render the olfactory nerves suscepti-
ble to the impression of odorous materials — fully demonstrated, if
in such individuals a finer perception of odours took place, by
injection of impregnated air into the nostrils, during inspiration than
during expiration.
Many will probably make the following objection to my theory
— namely, that it is not unlikely that the odorous materials which
we breathe are decomposed in the lungs; this does not, however,
take place. Agreeably scented air, the fragrance of which we have
already smelt, can, after it is expired, produce the same impression,
although somewhat weaker, upon reinspiration. If we swallow a
little strongly odoriferous substance, the oil of turpentine, for
example, or only apply a little upon the posterior part of the tongue,
13*
130 STROMEYER ON THE PRODUCTION OF SENSATION.
we imagine that we smell it during expiration ; but in this case the
difficulty of distinguishing taste from smell is so great, that we do
not know accurately which of those two senses has received the
impression.
The nerves of the fifth pair, distributed to the nasal cavities,
exert a certain influence during olfaction ; they feel probably the
mechanical impression of the currents of air, simtiltaneously with
the perception of the odour by the first pair of nerves. The
sensibility of the nerves from the fifth pair is not varied during
inspiration, for painful sensations in the nasal cavities are neither
increased by inspiration, nor diminished by expiration. Magendie's
experiments appear to demonstrate that the connexion of the nose
with the respiratory organs, which is indicated by the act of sneezing,
depends upon the fifth pair of nerves, as, after division of the
olfactory nerves, sneezing may still be excited by irritation of the
nasal cavities. The olfactory nerve, on the contrary, is insusceptible
of ordinary sensation ; it may be pinched, or otherwise mechanically
injured, without the production of pain.
The greater part of the impressions which the nose receives are
undoubtedly of a mixed nature; they are compounded of olfactory
perceptions and common sensation. It is not alone the delightful
fragrance of the rose, perceived by the olfactory nerves, which
refreshes us, but likewise the cool fresh air produced by the evapo-
ration of its moisture, felt by the trigeminus. This explains why
perfumed essences are so much liked : the evaporation of their
contained spirits of wine produces refrigeration, which is felt at the
same time as the odoriferous oil is perceived. A similar mixed
impression is obviously connected with snuff-taking. In habitual
snuff'-takers, impression upon the olfactory nerve is wanting, and
the fifth nerve alone feels the mechanical and chemical stimulus of the
snuff". It is well known that the expiration which accompanies sneez-
ing is preceded by a spasmodic closure of the air-passages. We may
therefore correctly assume, that the expiration of sneezing is not
excited directly through stimulation of the nose, but secondarily,
or by reflex motion from the larynx, in the same manner as cough
arises through the contraction of the bronchi upon the matter to be
expelled, causing, by combination of motor and sensitive nervous
activity, a tickling sensation in the larynx, which then induces thie
peculiar expiration called cough. In sneezing, therefore, the jeflex
activity of the vagus, as motor nerve in the larynx, through
excitation of the trigeminus, as sensitive nerve, must be taken into
consideration. The reactions between the nerves of the nasal
cavities and the nervous vagus, are numerous. Many odours
produce uncomfortable feelings in very susceptible individuals — for
instance, the odour of rhubarb: other odorous articles diminish
already-existing indisposition — for example, acetic sether, or spirits
of hartshorn. Morbid perceptions of odorous materials are produced
most frequently by affections of the stomach. If olfaction be inti-
mately connected with any of the respiratory nerves, we must
TOUCH. 131
decide that it is with the vagus, in its office of motor nerve. The
importance of this connexion of the sensorial nerves of the nasal
cavities with the motor parts of the vagus, is evinced by the diffi-
culty of respiring during closure or obstruction of the nostrils; for,
in a mechanical point of view, respiration ought to be effected as
readily by the mouth as through the nostrils. Infants not unfre-
quently pass sleepless nights merely through the nose being ob-
structed by desiccated mucus.
Touch. — In order to examine an object by the touch, we usually
perform certain motions which, besides a manifold investigation of
the surface, inform us, by the degree of resistance experienced by
the finger, concerning the hardness or softness of the object. Active
movements of the feeling organ are nevertheless not indispensably
necessary to enable us to judge of the nature of the surface of a
body, for we can also feel the body which touches us, but much
more distinctly that which we ourselves touch. Our attention
concentrates itself more upon the finger we move. Thus, let a
person take a large coin, and gently rub its inscription or portrait
upon the tip and anterior surface of a finger, in a manner similar to
that in which he would have moved the finger over it. The majority
of persons upon whom I have observed this experiment could not
distinguish the head from the inscription. Some said it seemed as
if they could not feel with the finger. This may be explained,
it is true, through the unaccustomed mode of application of the
sense of touch. The cause of it may, however, lie deeper, and the
concentration of the attention upon one finger may depend upon the
operation of the will upon the muscles. I have met with some
individuals who, in the above-mentioned manner, could feel very
distinctly; the experiment therefore leads to varying results. But
this must not surprise us, for nobody will deny that our will may
act upon the muscles without causing visible motions; for in en-
deavouring to hold any part (a finger for example) in a given
position, we a
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It would seem that the mortality of the whole English population
between theages of 20 and 40, was higher than in Belgium and Sweden,
The mortality of children, under five years of age, has materially
decreased in England within the last century — a fact h priori pro-
bable, and not at all inexplicable. In London, the bills of mortality
VITAL STATISTICS. 211
prove that, in the 20 years, 1730-49, out of 100 born, 74-5 died
under the age of 5 years, while, in the 20 years, 1810-29, only 31-8
died out of the same number.
2. Influence of Sex on Mortality. Professors of statistics
would seem to commit blunders like less exact folks, or at all events
to disagree to a considerable extent. Nay, there is among them not
a little of that spirit which distinguishes carpenters, tailors, m.embers
of trades, two of whom are said to be never capable of a very lively
friendship. Thus, Mr. Edmonds abuses Mr. Rickman and Mr.
Finlaison, and Mr. Farr would appear to cleave to Mr. Edmonds.
But this by the way.
If any point was considered established it was the superiority of
female over male life. Nay, a Life Assurance Company in London
has, within these few months, acted publicly on that conclusion, and
lowered the premium on female insurers. But this would appear
to be a delusion, and the Assurance Company would seem likely to
make a sorry bargain.*
Contrary, says Mr, Farr, to the Swedish observations, the morta-
lity of females, between the ages of 10 and 40, is higher than that of
males ; it is only in childhood and after the 50th year, that the
mortality of females is lower than that of males.
3. Differences of Mortality in the counties, towns, ^c. of Eng-
land. Some of the counties of England are much less healthy than
others are. Cornwall and Devon are the healthiest — Cambridge,
Kent, Surrey and Middlesex the reverse. The counties in which
the greatest number of inhabitants are congregated in towns, are
generally the most unhealthy.
Mr. Edmonds, whom Mr. Farr copies, divides the English coun-
ties into eight classes. In class 1, are Cornwall and Devon. — In
class 2, Wales and Monmouth. — Li class 3, Dorset, Somerset, Wilts,
Gloucester, Hereford, Northumberland, and Cumberland. — Ii class
4, Westmoreland, North York, Rutland, Norfolk, Suffolk and Hert-
ford. In class 5, Durham, East York, West York, Leicester and
Lincoln. — In class 6, Salop, Derby, Northampton, Huntingdon,
Essex, Bedford, Bucks, Oxford, Berks, Southampton, Sussex. In
* We can state as a fact, that a large and ably-conducted Life Assurance
Company in London, has met with its greatest losses on its female lives. It has
had no inducement to lower the rate of insurance on those lives. On the con-
trary, it would willingly reject all insurances on women; and, but for the loss
of business and the odium which such a singularity might entail on it, it is far
from impossible that such a step would be taken. It is probable that many cir-
cumstances contribute to diminish the value of insured female lives. The pre-
liminary examinations of a woman's state of health can seldom be so searching,
or at least so accurate, as those of a man's. Women do not scruple to deceive,
and a practical acquaintance with their habits and their conduct establishes the
conviction that, in all classes, they possess a feebler sense of the obligation of
truth, in the ordinary business of life, than men have. Why this should be, we
leave to causists to determine. Assurance Companies have discovered that it
is so.
212
VITAL STATISTICS.
class 7, Lancaster, Chester, Nottingham, Stafford, Warwick, Wor-
cester, Cambridge, and Kent. In class 8, Surrey and Middlesex.
The mortality of the inhabitants of the counties, thus arranged, is
displayed by Mr. Edmonds in the following table.
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VITAL STATISTICS. 213
The mortality of cities is highly interesting, not only to their
inhabitants, but to the whole nation. The grandeur of a people
depends on their multiplication, their wealth, and populousness. If
the marts of commerce are, as Dr. Price has designated them, the
" graves of men," we must first deplore — then attempt to remedy
the evil. A necessary evil, to some extent, it probably must ever
be ; yet the history of London is sufficient to prove that much has
been done, and to render it probable that more may be done still, to
augment the salubrity of cities.
A table is given for the purpose of showingthe increasing mortality
in Glasgow. It shows, too, the lesser mortality of females in that
city — a fact treated by Mr. Farr as a gross .blunder on the part of
Mr. Finlaison. It appears from the table, that between the ages
of 30 and 60, the mortality of each sex has increased 20 per cent,
every five years between 1821 and 1835. This is attributed in part
to the augmented influx of the Irish, who introduce their national
habits and national fevers. By a report of the Glasgow Infirmary
it seems that, in 1835, out of 3,260 patients treated, 1,258 had fevers,
and of these 125 died.
The relative mortality of England, Scotland, and Ireland cannot
at present be determined. But the following calculation may lead
to an approximation to the truth. The number above the age of 60
years' alive, for every 100 living between the ages of 30 and 60,
was, in —
England and Wales . (Females) 27'5
Scotland (Females) 28-0
Ireland . . . (Males and Females) . . . 15-7
Belgium. . . . (Males and Females) . . . 30*3.
4. Influence of Foreign Stations on our Army. This is shown
in a table compiled by the diligence of Mr. Marshall, a highly intelli-
gent surgeon.
The mortality of the native troops in the Madras Presidency was
only 1-4 per cent. ; that of the European troops was quadrupelled
in Bengal. At home 1-5, in Bengal 5*7 per cent, of the European
troops died. The climate of the East Indies is, therefore, congenial
to the Hindoos, and only extraordinarily fatal to foreigners.
The mortality of the French infantry is greater than that of our
own army on the home station. Its mean annual rate per cent, is, for
the troops of the line, 2-00 — for the Garde Royale, 1-47 — for the
whole army, 1-94.
20^
214
VITAL STATISTICS.
Table of the Mortality of the British Army, showing the mean
Number of Annual Deaths out of 100 living at each Station men-
tioned.
Time and Place of
Observation.
English Army.
Extent of Ob-
servations.
Annual Rate of
Mortality per cent.
Average
Force.
Years.
Maxi-
mum.
Mean.
Mini-
mum.
*The United Kingdom . .
*Ireland, 1797-1828 ....
Mediterranean.
*Malta, 1824-31
*Gibraltar
British Army . . . .
Ditto
The garrison ....
Ditto
The troops
(1) European troops
Native troops . . . .
(2) European troops
1796-1805, ditto . .
1810-28, ditto
Ditto
Colonial troops, \
(Blacks) \
46,460
36,921
2,226
3,267
3,467
11,820
69,550
8,700
13,610
5,768
■ 2,528
2,733
10
32
8
17
13
4
4
7
10
19
19
19
"i-Q
2-8
13-4
3-6
71
1-6
9-7
27-7
23-4
47-2
8-4
1-5
1-5
1-5
2-0
2-6
4-8
1-4
5-7
18-3
11-3
15-5
5-5
11
1-0
0-7
1-4
3-2
1-0
3-8
8-0
4-7
7-8
1-8
*Ionian Islands
East Indies.
*Fort St. George Presid. )
*Madras, 1827-30 C
*Bengal, 1826-32
West Indies.
*Windward Islands . . . )
*Leeward Islands . . . . ^
* Jamaica Honduras, }
1810-28 \
^Jamaica, Honduras, ^
Windward and Lee- >
ward Islands )
Mortality is usually the result of sickness. The former has been
reduced by the formulae of calculation to something approaching to
certainty and rule. Will sickness submit to similar calculations ?
At first sight it might appear difficult, if not impossible, to procure
adequate data ; nay, ci priori, it does not seem to follow, that because
death observes an appreciable ratio to age and sex, sickness will do
so too. It is certain that the laws of sickness can never be deter-
mined with anything like the same precision as are those of death
— because death is chronicled in all classes, and sickness is not. It
is only under peculiar circumstances, that attacks of sickness are
regularly, or may be regularly registered — amongst official employes
whose absence is felt, and whpse illness must be certified. This
is one obstacle to accuracy. But the very term sickness is indefinite.
One person will lie upon the sofa for a cold — the mechanic, affected
with the same complaint, will pursue his unceasing and laborious
occupation. Some persons, of weak habits and infirm health, may
be said to be always labouring under sickness — that is, they suffer
ailments which would utterly disable from active employments,
but which yet suffer them to engage in sedentary or light occupa-
tions. A diligent pursuit of the details of sickness — a careful
observation of the habits of individuals and of classes, would enable
the inquirer to ascertain and to point out the numerous sources of
VITAL STATISTICS.
315
fallacy and of doubt, that must surround the attempt to enunciate a
law of sickness.
The benefit societies, whose necessities have forced, and whose
circumstances have enabled them to calculate, to some extent, the
liabilities to sickness, arrange that under three heads — Bedfast
sickness, when the individual is absolutely incapable of exertion —
walking sickness, when the patient is incapable of entire attention
to his concerns, as he is in many chronic diseases, after reduced dis-
locations, and so forth — and permanent sickness, as is the case of
the paralytic, the maimed, the incurables.
From a table showing the proportion of sick out of 100 living at
each interval of age, in friendly societies, it appears that, between
the ages of 30 and 40, 1-32 are constantly sick in the Scotch benefit
societies, and 1-83 in the English. Between the ages of 60 and 70,
10-80 are ill in the former, and 11-26 in the latter. Thus, the sick-
ness increases with the age. The time for all ages is 2*45 in the
Scotch societies — 2-76 in the English.
In the parish of Methven, in Perthshire, it was ascertained that
35 out of 743, or 4*7 per cent, of the male population, above 15,
would not, from bodily or mental infirmity, have been admitted as
members of the friendly societies at all.
Bad health, however, and sickness are not, in the poorer classes,
equivalent terms. Thus, Dr. Forbes ascertained, by personal exam-
ination of 120 Cornish miners, in actual employment, that only 63
had good health ; of the remaining half, 2Q had difficulty of breath-
ing, 14 pain of chest, 10 pain of stomach and bowels, 5 lumbago,
pain of shoulder, palpitation, scrofula, or fits. Out of 115 children
below 18 years of age. Dr. Bisset Hawkins states, that 84 had good
health ; 25 middling health ; 6 bad health. Of the miners at work,
only 53 — of the factory children only 73, per cent, enjoyed good health.
A return has been made from the various dockyards, of the num-
bers of workmen sick in the years 1830, 1831, and 1832, and the
following table exhibits a condensed view of the facts that they
convey.
Table presenting a condensed View of the above Facts.
Years.
Average
Number
of Men.
Number of Cases.
Days of Sickness
from Spon-
taneous Disease.
Days of Sick-
ness from
Injuries.
Total days
of Sick-
ness.
•Diseases.
Hurts.
1830
1831
1832
2,079
2,002
1,867
697
888
665
357
325
329
9,188
9,605
8,617
5,884
4,620
5,086
15,072
14,225
13,703
3 yearsi 5,939
2,250
1,011
27,410
15,590
43,000
This table furnishes, as the mean of the three years, the following
interesting results. In the year, 1 man in 6 is seriously hurt ; 2 in
216
VITAL STATISTICS.
5 fall ill. Each man, on an average, has an attack of illness, either
spontaneous or caused by external injury, every 2 years ; and, at
an average, each disease lasts 14 days. Mr. Farr goes on to observe,
that it may safely be assumed that, of the 21,000 labours employed
in the dockyards, 2 per cent., or more than 420, are constantly
kept at home by diseases, two-thirds of which are independent of
accidents.
The most accurate report which has been yet published would
seem to be that of the state of health among the men employed by
the East India Company in London. It is contained in a supple-
mentary report, by Dr. Mitchell, to that of the Factory Commis-
sioners. It was " in the form of a large volume, containing a list
of 2,461 labourers, employed in the month of April, 1823, with a
statement of the number of days' illness experienced by these la-
bourers, one by one, year by year, for the ten succeeding years ; also
the date of every death, and the date when any labourer ceased to
be employed, by being superannuated and pensioned, dismissed, or
by voluntarily leaving the service of the Company."
Ever}"" labourer put upon the sick list is allowed Is. 6d. a day,
Sundays included ; he is also seen every day by the surgeon, and,
therefore, remains no longer absent than the case requires.
During the 10 years, 496 died, 248 were pensioned, and 208 left
the service or were dismissed. The reporter. Dr. Mitchell, has cal-
culated a table of the duration of sickness per annum for every age,
from 16 to 81, which we subjoin: —
Age.
Average dura-
tion of Sick-
ness per ann.
for every Man
employed.
Average dura-
tion of Sick-
ness for every
Man sick.
Age.
51 to 61
61 — 71
71 — 81
Average dura-
tion of Sick-
ness per ann.
for every Man
employed.
Average dura-
tion of Sick-
ness for every
Man sick.
Under 21
21 to 31
31 — 41
41 — 51
Days.
. 4-02
4-94
5-06
5-31
Days.
1396
18-70
22-63
23-21
Days.
7-00
10-08
11-63
Days.
28-60
29-07
31-77
From other calculations and another table, it appears that the
annual rate of mortality was 3-13 per cent. Notwithstanding the
selection of healthy men as labourers, the deaths between the ages of
40 and 60, agree very nearly with the general mortality of males in
London, between the years 1813 and 1830. Amongst the labourers,
from 40 to 50, the annual mortality was 2-43 ; amongst the male
inhabitants of London, it was 2*54 — amongst the males inStockholm,
from 1755 to 1763, it was 4-67. Between the ages of 50 and 60,
the mortality of the labourers was 427 — of males in London, 4-04
— of males in Stockholm, 6-46.
The mortality under 40, observes Mr. Farr, is not so high among
the labourers, because the greater part of them are selected healthy
VITAL STATISTICS. 217
men, received into the service between the age of 20 and 35 ; after
50 it is higher than the general mortality in London. These men
were well supplied with food and clothing ; their work without
being hard insured regular muscular exercise ; in sickness they had
rest and proper medical attendance ; yet between 40 and 50 the
mortality was 67 per cent, between 50 and 60 as much as 82 per
cent, higher than the mortality at the same ages in all England.
Such facts as these annihilate the supposition, that the increased
mortality in cities is due to want of food and greater misery ; nor,
although these men drank freely, can we admit that their moral
habits differed so greatly from those of country labourers as to account
for their greater mortality.
Of the 2,461 labourers, 10 per cent, were pensioned in the course
of ten years ; 8 per cent, were discharged, or quitted the service ;
1 man in 81 working a year was pensioned ; 1 in 4 had an attack
of sickness ; 1 in 60 was constantly on the sick list ; 1 in 21 (4*79
per cent.) of the labourers was a pensioner ; and 1 in 6 of the pen-
sioners died annually. Some other observations on this head we
pass over. They merit the attention of benefit societies, but do not
require our's.
Two tables are given of the sickness of factory labourers in Lan-
cashire and Glasgow. But it seems that they are open to objection,
and we therefore pass them by. So far as they go, they exhibit a
greater amount of sickness in the females than in the males, both
in Lancashire and Glasgow.
The mortality of the English army is higher than the mortality
of the general population ; and the sickness, including every class
of disease, is more than twice as great as that recorded in the pre-
ceding tables, at the ages 20-35, which correspond nearly with the
ages of the troops. The mean proportion sick per cent, in Ireland
(1797-1828), observed on an average force of 36,921 men, amounted
to 5*1 ; but a certain proportion of the sickness in the army is from
syphilis, and this is not included in the other observations. In the
English army — cavalry, foot-guards, and infantry — Mr. Finlaison
has estimated the numbers of sick, in the years 1823-4, as somewhat
more than 4 per cent.
The sick time in Madras, remarks Mr. Farr, in 1808-9 was 12*4
per cent, of the lifetime. Annesley considered 10 per cent, in that
climate unhealthy ; and this appears to be near the mean proportion
of European troops constantly sick in the East Indies. In places
where the mortality is high, the rate of sickness fluctuates very much
from year to year ; and, exclusive of losses in battle, the mortality
and sickness are tripled or quadrupled in a campaign. This kind
of knowledge is still imperfect, although indispensable to those who
would employ masses of men with effect in different circumstances.
5. Morhility of the Population. Passing over some tables, we
introduce a rather lengthened extract, which contains the results of
many different inquiries.
218 VITAL STATISTICS.
"The attacks of disease vary in frequency to a great extent in
unhealthy and salubrious situations : but the experience of the East
India Company's labourers, of the children belonging to theBennet-
street School, which has the best-regulated sick society of any in
Manchester, and of the artisans of the Trades Club in Wurzburg, all
receiving pay during sickness, and only falling on the funds in
cases of some duration and severity, tends to show that 100 of the
efficient male population of this country are not liable to more than 25
severe attacks of disease in the year. Each man is liable to a pro-
tracted disease, disabling him from work,every fouryears : this forms
one great section of the sickness af the country ; but it does not in-
clude syphilis, accidents from fighting and drunkenness, or the many
ailments which make men apply for medical advice, while they carry
on their occupation, comprising, perhaps, as many more cases of a
slighter character, which raise to 50 per cent, the proportion of the
population attacked annually. In the Portsmouth dockyard 37-8
per cent, of the men fall ill, 16 per cent, meet with accidents in the
year : besides accidents, the attacks of sickness in Sheerness amount-
ed to 43-7 per cent. The reported attacks of sickness in Sheerness
are exclusive of accidents ; and if, as is probable, the same exclusioa
was made in the other returns, the spontaneous cases amounted to
nearly 50 per cent, in Chatham and Pembroke. By excluding the
slighter cases the attacks of sickness may be reduced near the level
of the preceding series : in the healthiest dockyard, Plymouth for
example, out of 2,147 cases, 635 did not exceed three days' duration ;
and by subtracting these, the proportion attacked in 100 will be re-
duced from 34-7 to 24-4. Accidents, although excepted here, ought
not to be excluded, because they occur as common inevitable causes
of disease among all classes of the people, and raise the sickness to
a considerable, although varying, extent ; in Portsmouth, the increase
of cases from this cause was 42 per cent. Except Plymouth, the
dockyards appear to fall somewhat below the national standard of
health ; more than 50 in 100 of the men are attacked by sickness of
one sort or other annually. In Sheerness, out of 1,422 cases of
sickness, 263 were agues, 142 rheumatisms, 68 colics and cholera.
The report of the Liverpool Society, by the surgeon, Mr. Parr,
shows that 57'2 per cent, of the members receive medical advice in
the year. Mr. Parr makes a useful distinction between the patients
attended at their own houses and those seen at his surgery : the first,
not quite comprehending all disabled for work, were 17*8 per cent.,
nearly a third of all the patients treated. Among 100 members,
8-6 met with accidents in the year. The return from the Deanston
Cotton works, in Scotland, after deducting cases of less than three
days' duration, makes the annual attacks of sickness among males
20, among females 448 per cent. . This difference between males
and females deserves attention ; it is produced by rheumatisms,
diarrhceas, and even wounds, but more particularly by catarrh and
headach. The female cases approach the nearest to the total attacks ;
as the wages of women are lower, and they give over working abroad
VITAL STATISTICS. 219
on slighter occasions than males. Almost an equal difierence is
visible in the Lancashire 'cotton works ; in Glasgow the difference
is trifling. Females leave off work, and apply for medical advice,
more frequently than males ; but as the mortality between 15 and
40 is but a little higher, the same must hold respecting severe ill-
nesses. The cases observed in factories, only reported on the recol-
lection of the workmen, would very likely include nearly all the
serious diseases, and a varying proportion of the slighter distempers
which detained them from work. The attacks of sickness among
paupers — the feeble, crippled, maimed, idiotic, crazy,miserable, dirty,
dissolute, vicious, unfortunate — rejected as refuse from all the fore-
going classes, are more numerous than the attacks to which select
labourers are liable ; and medical men, in undertaking to attend
paupers, should bear this in recollection. For the facts relating to
English prisoners we are indebted to a highly interesting paper of
Mr. Ghadwick, in which, by collating the dietaries of 60 prisons in
England and Wales, he has rendered it probable that the lowest
prison diet does not increase sickness. An accurate return of the
average population of the prisons, the ages of the prisoners, the
diseases and deaths, the amount of labour performed, and information
concerning the ventilation of the cells, will, in a few years, settle
this question : the average population in this table was assumed
to be furnished by the numbers remaining at five times in each of
the 60 prisons.
"We are unacquainted with any data from which the absolute mor-
bility of the British population can be deduced, any more than the
mean duration of each case and the mortality of the sick, with which
it is intimately connected. Several interesting observations on
distinct classes, and on the morbility and duration of sickness at dif-
ferent ages, however exist. At the age of 20-50, the duration of each
attack among the East India Company's labourers was 22-2 days, and
with the pension time 36 days : 7'8 in 100 cases died, or 7*4 exclusive
of pensioners. The duration of these cases approaches very near
the term of treatment in 14 Paris hospitals, where patients are ad-
mitted indiscriminately, and continue till they recover or die ; in
1819-1S25, the mean number, 3,947 patients, remained 35 days. In
the hospitals of this country, where adults and more chronic cases
are received, but at the same time are often sent out before death
occurs, the patients continue longer under treatment ; in the county
hospitals (31) of Ireland, 38-3 days ; of England, 39-4 days ; of the
metropolis, 42 days. Where slighter and ephemeral cases are
counted, and organic diseases are excluded, the duration of cases
among adults does not, according to the returns from the dockyards,
exceed 12 days. In Corfu, 1816-1821, the mean duration of all the
diseases (14,098) was 16*1 days.
" It is of great importance for medical men to know the average
number of deaths in all the cases that come under their care, in order
to judge of the remedial influence of medical appliances. The
hospitals furnish some, although inadequate information on this head.
220
VITAL STATISTICS.
The sanability of the sick appears to decrease in the large cities ;
partly, it may be, because more serious accidents are admitted."
Hospitals.
In-patients
treated in
1 Year.
Mean
Number
of In-Pa-
tients.
Deaths.
Deaths
out of
100 Pa-
tients.
Deaths in
36-5 days
out of 100
Patients.
Salop, 4 years (1830-33) . . .
Winchester, 1 year (1833-4)
Salisbury, 1 year (1833-4) . .
Chester, 2 years (1833-5) . .
Manchester, 1 year (1831-2)
Liverpool, 1 year (1831) . . .
Bristol, 1 year (1828-9) . . .
London, 7 hospitals
955
798
894
489
1,784
1,960
1,483
18.740
92
83
88
45
128
220
195
2,191
34
31
27
20
128
109
160
1,605
3-7
3-8
31
4-2
7-2
5-6
9-5
9-0
3-6
3-7
31
4-5
100
50
8-2
7-6
Men placed under the same circumstances, appear equally liable
to an attack of sickness between 11 and 60 years of age ; 100 of the
London labourers, in each of the decennial periods between 20 and
60, had nearly 23-5 attacks of sickness annually.
Two other positions are laid down : — 1. That the mean duration
of each case increases as age advances ; 2, that the mortality among
the attacked augments with age, at the same rate as the mortality
among the entire number living.
"The sick time increases with age in a geometrical progression.
If, therefore, the number of attacks, at each age be the same, the
duration of each attack will increase in the same ratio ; and con-
versely, if the duration of the cases and the sick time augment at
the same rate, the number of attacks at every age will be equal.
Any two of the elements being given, the third may always be
deduced from them. Again, if the mortality of the attacked increase
at the same rate as the mortality of the entire population, the
proportion attacked at every age will be the same. Amopg the
London labourers, the mortality between 30-40, 40-50, was 1'48
in 100 living ; the mortality among 100 attacked was 6'5, 10"4. 2-43,
Now 1*48 is to 2 43 very nearly as 6'5 is to 10"4 ; and it results
from this that the attacks, whatever their absolute number may be,
whether 22 or 52, were the same in both periods."
6. Diseases. There is not much in the observations upon these
to give us pause. The writer enters into a calculation to show that
if the same number of persons died by ordinary chronic diseases
who at times die from short and epidemic ones, a vast deal of misery
and a great deal of inconvenience would ensue. As this may readily
be granted, we pass on. Has insanity increased ? The returns are
yet unequal to the solution of this question, for an obvious source
of fallacy sticks to them. Formerly, the gross ill-treatment of
lunatics must have shortened their existence. Now they live longer,
and consequently, more will be alive at a given time, independently
of an increase of numbers relatively to the populatioxi. The same
fallacy applies to the present estimates, between the numbers of
VITAL STATISTICS. ' 221
insane in town and country. The superior longevity of the latter
may similarly and deceptively swell their numbers. Sir A. Halli-
day calculated that, in England, 1 in 1000 of the population is
insane — in Wales, 1 in 800 — and, in Scotland, 1 in 574. But a
calculation, more exact in its data, of the mad amongst the Quakers,
makes them amount to 3"4 in 1000 — and perhaps this is an approach
to what obtains among the more opulent classes in England.
In the paper of Mr. Palmer, we find some further observations
on insanity, which we may here introduce. The points to which
we shall advert are, the diminished mortality of lunatic asylums,
and the compai-ative. frequency of the disease in men and women.
It appears (says Mr. P.) by nearly all the returns of Europe,
excepting France, that men are more prone to insanity than females
in the proportion of 100 to 77 : but this apparent discrepancy may,
perhaps, be referred to the delicate feelings of relatives, who object
to the idea of placing the female branches of their families in
public asylums, especially as they are more easily controlled at
their own homes or in private families. The proportion of females
cured at the Bethlem Hospital, during the last 15 years, has been
47'0 per cent. ; and at St. Luke's, 44*8 per cent ; the respective
numbers for males being 39"6 and 41'3. — Of 997 curable patients,
admitted at the former, from 1830 to 1834 (inclusive), considera-
bly more than half were between the ages of 20 and 40, or pre-
cisely at that period of life when the passions acquire their greatest
ascendency. The mortality, during the same period, was a little
less than 1 in 25, which is surprisingly small, when we consider
that many of these labour under actual organic disease of a vital
part. Of the recoveries, nearly one-half took place within the first
six months.
In connexion with insanity, we may not unnaturally glance at
the suicide. Is he more frequently an Englishman than a foreigner ?
Popular credulity, Continental -abhorrence of our customs and our
manners, and our own paradoxical love- and abuse of our country,
our climate, and ourselves, have stamped self-destruction as a national
characteristic, and 'as the peculiar offspring of the gloom and fogs of
November. Exact investigations absolve us from this national
weakness or crime, and prove that we are less suicidally inclined
than the German or the Frenchman.
About 100 instances only of suicide annually occur in the metro-
polis. From 1812 to 1824, continues Mr. Palmer, the total number
of suicides for the city of Westminster was only 290, or 1 in 8000
— a proportion at least three times inferior to that for any of the
great cities of France or Germany ; and if allowance is made for
the extreme dissipation of many parts of this city, we shall not be
far wrong in considering 1 in 10,000 a medium proportion. In
Prussia, the civic cases are to the rural as 14 to 4. The propensity
is stronger in the male, than in the female, as 5 to 2, in this country,
and 2 to 1 in France. Many curious exam.ples are recorded of the
influence of imitation, in determining the thoughts to suicide, espe-
' m 31
222 VITAL STATISTIC©.
cially of those who are predisposed. The shocking recital of hor-
rible cases in the newspapers, is attended with this eflfect. It has
occasionally become necessary for the public authorities to interfere,
and either to deny the rites of Christian burial, or to expose the
corpse to some indignity, in order to arrest the progress of a suicidal
contagion. Dr. Caspar relates the existence of a suicidal club in
Prussia, consisting of six persons, all of whom accomplished their
purpose ; and a similar club is said to have existed in Paris not long
since, the members of which bound themselves by a regulation that,
every year, one of their number should be selected to destroy him-
self as a testimony of their sincerity. Among the causes of suicide,
sheer misery holds a prominent place ; next to that, domestic unhap-
piness ; then reverses of fortune, disappointed love, and gambling.
A great number of attempted suicides arise from the loss of female
honour, accompanied by the prospect of pregnancy. It is remarka-
ble, that this disposition is far more predominant in Protestant than
in Catholic communities. In Spain it is so extremely rare, that for
the whole of 1826, only 16 instances were officially reported. From
1812 to 1824, the suicides committed in Westminster, in the
months of June, were 34, and those in the months of November,
22. In 1812, 1815, 1820, and 1824, the months of November did
not afford a single case.
We are next presented with tables, exhibiting the fatal dis-
eases of London for the last two centuries. They are distributed
in six columns, and embrace the following periods of time. Column
A is deduced from 65,706 observations, made in the seven years,
1629-35. Col. B from 426,253 diseases, recorded in the twenty
years, 1660-79. Col. C from 732,873 deaths, occurring in the thirty
years, 1728-57. Cols. D and E each embrace periods of ten years,
1771-80 and 1801-10. Col. F presents the results of the five last
bills of mortality, 1831-5, and the actual fatal diseases of London,
so far as they are shown by the present system of registration. The
table containing these six cblumns, exhibits the relative fatality of
a vast number of existing, and of many forgotten diseases. Thus,
the "chrisomes," "overlaid," " mold-shot head," "liver-grown,"
"griping of the guts," "rising of the lights and mother," "jaw-
fallen," "planet-struck," raise their grisly and portentous fronts in
the old bills, but, pressed in modern science and nomenclature, slink
out of the new.
This table is too long for us ; but there is another, equal in inter-
est, and superior in conciseness, which displays the fatality of the
principal diseases in the several periods we have mentioned. The
observations are made on 100,000 living in each period, and the
whole mortality, as well as the particular, are shown.
VITAL STATISTICS.
223
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