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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

^ <X l^riij^^vl^ar 1836. By Professor Muller, of Berlin. . .229

[From tl^ British and Foreign Medical Review.]

PREFACE.

[BY THE EDITOR.]

In looking over tlio British Medical Journals, expe-
rimental essays of a decidedly original cast, and re-
views, being a digested summary of multifarious facts
and opinions, are met with. Several of these have been
transferred by the editor to successive numbers of
"The Eclectic Journal of Medicine.'^ But others
remained which were too voluminous for insertion in
this manner. Of late it has iso happened that in one
department alone. Physiology, papers of great value
have appeared in the British Journals, and which it is
highly desirable to place before American readers. Ex-
tracts and partial analyses would have exhibited an
imperfect view of their nature and merits, though it is a
plan which reviewers in many instances pursue with
advantage. From this dilemma, insurmountable in com-
mon Journals, the peculiar nature of our's enables us to
extricate ourselves. We have but to collect and arrange
the essays which seemed to us of most interest, .and intro-
duce them into the "Library." This we have accord-
ingly done. The selection is such that our readers will
be placed in possession of a body of experimental facts
and important deductions, of a novel and attractive
character, relating both to the ultimate structare and
organization of the nervous system, the functions of some
of its chief divisions, and the mode in which these func-
tions are combined and alternated.

The essays by Dr. Reid, Professors Ehrenberg and
Stromeyer, and the excellent digests on Vegetable Phy-

4 PREFACE.

siology, and of the labours of Professor Muller and Dr.
DucHATELET, are fit company to the classical work of
Dr. Edwards, also published in the "Library;" and, to-
gether with it, will constitute a body of important physiolo-
gical problems and discoveries, and of principles in hy-
giene, which it would be impossible to find, in the same
compass, in any volume extant.

The present brief preface ought not to be concluded
without an acknowledgment of the liberality with which
the editor, in making his selections, has been seconded by
the publishers and proprietors of the Library, on the score
of the numerous illustrative engravings which they
have so cheerfully furnished. If these, on the plea of
justifiable economy, had been withheld, the valuable and
original paper of Ehrenberg could not have appeared,
and would probably have been lost to a very great ma-
jority of the medical public.

AN

EXPERIMENTAL INVESTIGATION

INTO

THE FUNCTIONS OF THE EIGHTH PAIR OF NERVES,

OR

THE GLOSSO-PHARYNGEAL, PNEUMOGASTRIC,
AND SPINAL ACCESSORY.

BY JOHN REID, M.D.,

Fellow of the Royal College of Physicians of Edinburgh, Lecturer on the Institutes of Medicine,
formerly Demonstrator of Anatomy, &c.

The Eighth Pair are undoubtedly the most interesting and im-
portant of all the nerves of the body, both in a practical and theo-
retical point of view. Their lesions are attended by the most
serious derangement of the respiratory and digestive processes, and
bear in a prominent manner upon some of the principal doctrines
in physiology. The functions of these nerves have, therefore,
commanded a more than ordinary degree of attention, and the in-
dustry and talent of numerous observers have been directed to-
wards their elueidation. In entering upon an experimental inves-
tigation into the functions of the three divisions of this pair of
nerves, I was fully aware of the numerous difficulties attending
such an undertaking, and have endeavoured to approach it with
all the circumspection and assiduity which its importance and in-
herent intricacies require. I, nevertheless, feel very considerable
diffidence in presenting the first results of this inquiry to the pub-
lic, since the data which I have obtained will necessarily lead me
to draw several important inferences regarding the functions of
these nerves, at variance with those entertained by many of the
most celebrated and experienced practical physiologists. And
most persons feel disposed to receive with caution or even dis-
trust the observations and opinions of one who can scarcely be
said to have finished his novitiate in the difficult task of unravel-
ling the operations of the complicated machinery of the higher
organized bodies, and the more especially when a considerable part
both of his premises and inferences are in opposition to those pro-
mulgated by physiologists, whose years and well-earned fame, ac-
quired by their long and laborious exertions in the extension of this
m 2

6 KEID ON THE EIGHTH PAIR OF NERVES.

science, entitle their opinions to the highest credit. Being con"
fident, however, from my previous pursuits, and from the great
care with which I conducted, after their death, the dissections of
all the animals operated upon, that I could not possibly be mis-
taken as to the particular nerves upon which the experiments had
been made ; profiting largely from the recorded errors and instruc-
tions of those who have preceded me in this field of inquiry j and
taking the very necessary precaution of making a careful repeti-
tion of the experiments under varied circumstances, so as to avoid
as much as possible any accidental sources of error, I have been
encouraged to publish the results thus obtained, — being satisfied
that the facts will be found, upon actual examination, such, or at
least nearly such, as I represent them. In entering upon this in-
vestigation I had no favourite theory to defend, stood committed
to no preconceived notions, or shackled by any slavish deference
to authorities, but was ready and willing to give up any of my
former opinions as soon as they appeared to be inconsistent with
the phenomena which presented themselves ; and I sincerely hope
that I am not chargeable with the opposite and equally dangerous
fault of seeking and hankering after novelties.

In stating the experiments, I shall enter more fully into the
details than many may think necessary, as it appears to me that
it is an object of essential moment to mention all the circumstances
under which any important experiment is performed in physiolo-
gical investigations, where so many extraneous circumstances are
apt to interfere with the results ; and I am convinced that if this
plan had been more fully followed, many a controversy might have
been avoided, as well as much animal suffering spared, and the
science would this day have presented fewer discordant statements,
and less unfortunate collision of opinions. It may appear to some
that I have repeated many of those experiments with unnecessary
frequency, and a wanton sacrifice of animals. But I naturally felt
diffidence and distrust in the accuracy of the results which I obtained
when opposed to those of more experienced observers, and it was
only after repeated and careful examination of the phenomena, that
I could feel myself justified in calling these in question. It is also
sufficiently obvious, that nothing is more injurious to the progress
of science than hasty and partial observations; and I was anxious
to avoid, as far as I possibly could, adding to that mass of conflicting
evidence, which there is already so much reason to deplore. Be-
sides, as every false observation requires additional experiments for
its refutation, I felt that, with less extended opportunities of wit-
nessing the phenomena under examination, I must incur a greater
risk, not only of throwing obstacles in the way of the progress of
truth, but also of occasioning a useless infliction of animal pain.

In detailing the following experiments, and the conclusions which
I feel inclined to draw from them, I shall follow the order in which
the nerves, generall}^ included under the eighth pair, are enumerated,
and therefore commence with the Glosso-pharyngeal.

GLOSSO-PHARYNGEAL NERVE. 7

PART I.

Glosso-Pharyngeal Nerve.

The experiments on this nerve were all performed upon dogs,
and were twenty-seven in number. Seventeen of these were for
the purpose of ascertaining if it were to be considered a nerve
both of sensation and motion ; and what are the effects of its
section upon the associated movement of deglutition, and on
i\\Q sense of taste. The other ten were performed upon animals,
immediately after they had been deprived of sensation, with the
view of satisfying myself more thoroughly, how far it is to be con-
sidered a motor nerve. In cutting down upon this nerve in the
living animal, the following plan was adopted after a careful ex-
amination of the anatomy of the parts. An incision, varying in
length, in proportion to the size and species <5f the dog, was made
nearly parallel to the back part of the base of the inferior max-
illa ; its posterior termination always extending a short distance
over the anterior margin of the sterno-mastoid muscle. After
-eutting through the skin and platysma myoides or cutaneous
muscle, the two large veins which go to form the external jugu-
lar were each secured in a double ligature, and cut across between
the points tied. The glands at the angle of the jaw were removed
or dissected aside, and the carotid artery exposed. The artery
was generally first secured in a ligature below the hypoglossal
nerve, and before it had given off any of its large branches ; it was
then exposed above the hypoglossal, included in a double ligature
and cut across. This was found to be the most effectual method of
preventing the troublesome hemorrhage, which otherwise is apt to
occur from wounding the large arteries, arising from the carotid at
this point. After this, by a little dissection, the nerve was exposed
as it lies upon the lower margin of the stylo-pharyngeus muscle,
near its origin from the styloid process. One of the best guides in
displaying the nerve, is the osseous expansion connected with the
tympanic cavity of the temporal bone, which is always readilj^
felt after the carotid has been exposed. In dissecting the nerve
back to iho, foramen lacerum posterius, great care must be taken
to separate it from ihe pharyngeal branch of the par vagum, which
lies sometimes in immediate contact with it, at other times one or
two lines below, and is frequently united to it by a considerable
communicating branch, so that it may readily be mistaken for a
large pharyngeal branch of the glosso-pharyngeal. I am afraid, for
reasons to be afterwards stated, that sufficient precautions have not
been taken by other experimenters to separate these from each other.
This is the more necessary, as I am confident that these two nerves
differ very materially in function, and this must consequently have
seriously affected the results. The superior laryngeal branch of the
par vagum is placed a short distance below these two nerves, but

8 REID ON THE EIGHTH PAIR OF NERVES.

was rarely seen except when exposed designedly. I have observed
very considerable differences in the manner in which the glosso-
pharyngeal gives off its branches to the pharynx and fauces; some-
times it begins to give off small filaments soon after it has emerged
from the base of the cranium, and continues to give off a number of
small branches in succession, until it has furnished all the filaments
to the pharynx and fauces ; more commonly the nerve forms a sud-
den enlargement upon the lower margin of the osseous expansion of
the tympanic cavity, from which the principal branches to the
pharynx and fauces are given off, one or two of which are much
larger than the others. It is almost needless to add, that in all the
animals kept alive, after section of these nerves for subsequent obser-
vations, a considerable portion of the trunk of each nerve was re-
moved. The first point connected with the function of the nerve
to which I directed my attention was the disputed question, whether
or not it is to be considered both a motor and sensitive nerve. In
investigating this it has occurred to me, that the discordant results
obtained in late experiments may be explained. It is with this
object, as well as with the view of pointing out the difficulties I
encountered at the outset, that I have here given the details of the
first experiments, as they are put down in my notes taken at the
time. These may serve as guides to those who may afterwards wish
to turn their attention to this subject.

Is the glosso-pharyngeal a nerve both of motion and sensation ?
Exp. I. June 3, 1837. — The glosso-pharyngeal nerve was exposed
on one side in a middle-sized terrier, and irritated by pinching it
with the forceps, but no satisfactory evidence either of sensation or
motion was observed, even when tied tightly in a ligature and cut
across. When the same nerve was exposed on the opposite side,
a powerful and sudden convulsive movement of the muscles of the
throat and lower part of the face, followed the first pinch of the
forceps. . After I had satisfied myself that this could be readily
renewed by irritating the nerve, these muscular twitchings of the
face appeared to me to resemble so closely those produced by pinch-
ing a branch of the portio dura, that though confident that the nerve
exposed occupied the position of the glosso-pharyngeal, and that no
branch oi ihQ portio dura lay along the lower margin of the stylo-
pharyngeus muscle, yet I could not divest myself of the idea
that some unusual distribution, or some other cause, had thrown a
branch of the portio dura in our way. Another nerve, lying
immediately below this, and of somewhat smaller size, was exposed,
(which was afterwards ascertained to be the pharyngeal branch
oi W\e par vagum,) and experimented on under the supposition that
it was the glosso-pharyngeal. When this nerve was irritated, no
distinct contractions of the muscles of the throat were visible ; and
though the animal appeared to give some indications of suffering
when the nerve was included firmly in a ligature and cut on its
proximal side, yet these were far from being decisive.

Exp. II. — On exposing the glosso-pharyngeal nerve on one side

GLOSSO-PHARYNGEAL NERVE. 9

in a young dog, the same convulsive movements of the throat and
face were observed as in the preceding experiment. Being again
considerably perplexed whether this could be the glosso-pharyn-
geal or not, since most of the numerous muscles thus thrown into
convulsive action do certainly not receive any filaments from this
nerve ; while irritation of a branch of the portio dura, though
sufficient to account for the convulsive movements of the face,
could not, however, explain the extensive movements of the
muscles of the throat, I tied a ligature loosely around it, to enable
me to recognize it readily again, and exposed the nerve lying
immediately below, (pharyngeal branch o( par vagum,) as in the
preceding experiment. No convulsive movements were seen on
irritating this last nerve, and the indications of suffering were not
distinctly marked. The animal was then killed by blowing air
into one of the exposed veins, and the anatomy of the nerves
experimented on carefully examined, when we were satisfied be-
yond the shadow of a doubt, that the nerve, the irritation of which
vyas followed by such distinct convulsive movement in this experi-
ment, was the glosso-pharyngeal. On exposing the pharyngeal
branch of W\q par vagum and the glosso-pharyngeal on the opposite
side in this animal, as soon as it had ceased to breathe, and when
the constrictor muscles of the pharynx were much more fully
displayed than during the operation upon the animal when alive,
distinct contractions of these constrictor muscles were observed
after each pinch of the pharyngeal branch of Xho, par vagum with
the forceps : while the same irritation applied to the glosso-pha-
ryngeal immediately afterwards, was followed by no visible muscular
movement. Being now satisfied that in the preceding experiment
we had in the second operation divided the pharyngeal branch
of the par vagum instead of the glosso-pharyngeal, the animal
was killed, and the dissection proved that we were right in our
conjecture.

Exp. III. — The nerve was exposed on one side in a small cocker
dog affected with the distemper, but no satisfactory evidences of
sensation or muscular movements were observed. This might
arise from the sickly condition of the animal, or, as we shall imme-
diately show, from the nerve being only irritated anterior to, or on
the distal side of that part of the trunk where the pharyngeal
branches leave it.

Exp. IV. — The glosso-pharyngeal nerve was first exposed on
one side, and then on the other, in a middle-sized terrier. Very
forcible convulsive movements of the muscles of the throat and
lower part of the face, but more especially of the throat, were
observed on pinching these nerves with the forceps. On cutting
the nerve across, the same convulsive movements and indications
of suffering were noticed on pinching the nerve on the proximal
end, or that part of the nerve which retained its natural connection
with the medulla oblongata. These convulsive movements were
exactly similar to those observed when the nerve was entire.

2*

10 REID ON THE EIGHTH PAIR OF NERVES.

There were no convulsive movements on irritating the lower end
by the forceps.

Exp. V. — The nerve was exposed on one side in a middle-sized
full-grown pointer. When irritated by pinching it firmly with the
forceps, only very feeble convulsive movements of the throat were
excited, and such as would readily have escaped notice, had we not
been in search of them. Professor Sharpey of the London Uni-
versity College, was present from the commencement of this
experiment, and as we were proceeding to expose the nerve of the
opposite side, we were joined by Professor Alison. On irritating
the opposite nerve by pinching it with the forceps, the convulsive
movements of the muscles of the throat were distinctly marked, but
still in a less decisive manner than in some of the preceding expe-
riments. The nerve was then included firmly in a ligature. On
irritating the nerve on the proximal side of the ligature, the same
convulsive movements followed ; while no effect was observed from
the irritation of the nerve on the distal side, or that in connection
with the tongue and pharynx. The same difference in the results
was also obtained from the irritation of the two ends of the nerve
when cut across. We had in this dog an opportunity of contrasting
the manner in which muscular movements are induced through the
stimulation of a motor nerve, such as the hypoglossal, or the spinal
accessory, with that motion which results from the excitation of a
sensation, as appears to be the case when the glosso-pharyngeal is-
irritated. For while the stimulation of the hypoglossal and spinal
accessory on the distal side of the ligature was followed by con-
vulsive movements of the muscles to which they are distributed,
and of these only, the stimulation of the glosso-pharyngeal on the
same side of the ligature produced no visible effect. On the other
hand, irritation of the hypoglossal and spinal accessory on the
proximal side of the ligature excited no muscular movements
whatever, while excitation of the glosso-pharyngeal on this side
was followed by extensive movements in muscles, to the greater
part of which it sends no filaments. When the glosso-pharyngeal
was pricked with the forceps, the indications of suffering were
distinctly but not strongly manifested, but the application of a tight
ligature was evidently attended by intense pain, — an effect which
we were somewhat surprised to find also attended the application
of a tight ligature to the hypoglossal.* A fatal dose of prussic acid
was given, and the muscles of the throat more fully exposed, when
distinct convulsive movements of the constrictors of the pharynx
were observed each time that the pharyngeal branch of thejoar
vagum was pricked.

In dissecting the nerves after death, I was anxious to ascertain if
any possible explanation could be given, why the convulsive
movements attending the stimulation of the nerve should have

* Mayer has described a small ganglion on the root of this nerve in the dog.
and ox. He has seen it once in the human subject* — See Edia, Med., and Surg,
Jour., Vol. xliii. p. 486.

GLOSSO-PHARYNGEAL NERVE. 11

been so feebly manifested on the side first operated on, and I as-
certained that we had been experimenting on the nerve of this side
beyond or on the distal side of the origin of nearly all its pharyngeal
branches; while in the second operation we had been experiment-
ing on the trunk of the nerve prior to, or on the proximal side of
the origin of its pharyngeal branches. Dr. Sharpey examined these
dissections, and expressed himself satisfied with the accuracy of the
statements here given.

Exp. VI. — The nerve was first exposed on the left side in a
middle-sized terrier. On pinching the nerve the convulsive move-
ments of the throat were rather feeble, though perfectly distinct.
When proceeding to display the nerve on the right side we were
joined by Professor Sharpey. We first pricked the lingual branch,
by which I here mean the continuation of the trunk of the nerve
proceeding to the tongue after giving off its pliaryngeal branches,
(under the belief that we were operating on the entire trunk) and
neither convulsive movements, nor indications of suffering followed.
On dissecting the trunk of the nerve backwards towards the fo-
ramen laceruTU, and beyond the origin of the pharyngeal branches,
distinct convulsive movements of the muscles of the face and throat,
and decided indications of suffering were observed. On pricking
the nerve during the moaning of the animal, it was several times
remarked that the voluntary actions of the muscles of the throat
were interrupted by these convulsive starts.

This animal was killed a few days after, and it was ascertained
that while the nerve had been satisfactorily divided on one side,
one pretty large pharyngeal branch had been left on the other.
Dr. Sharpey also examined this dissection, and was fully satisfied
of its accuracy. The impression on my mind is, that this pha-
ryngeal twig was found on the left side, (the side first operated on,)
but as it is not expressly stated in my notes, I cannot positively
affirm it.

Exp. VII. — On exposing the glosso-pharyngeal nerve in a stout
terrier bitch, we found that irritation of the lingual branch was
attended by no visible muscular movements, and no decided indi-
cation of suffering; while on irritating some of the small pharyn-
geal filaments individually, which leave the trunk of the nerve
soon after it leaves the foramen lacerum, convulsive movements
of the muscles of the throat and face, and marked indications of
suffering followed.

It will be unnecessary to detail the results of the other ten
experiments which were performed to ascertain the effects of
irritating this nerve, as far as the indications of muscular move-
ments and common sensation are concerned. I may state, however,
that the facts detailed in the above experiments were amply con-
firmed by those which were subsequently performed. It was found
that the muscular movements excited by pinching this nerve varied
in degree in different animals, but were always distinctly marked
when the precaution was taken to irritate the nerve before it had

12 REID ON THE EIGHTH PAIR OF NERVES.

given off its pharyngeal branches. It was also repeatedly observed,
that when the nerve was cut across, irritation of the lower end, or
that in connection with the muscles, was followed by no move-
ment; while, on the other hand, irritation of the cranial end, even
when the nerve was divided before it had given off a single twig,
was followed by as powerful convulsive twitches as when the nerve
was entire. We also remarked more than once, that while the
pinching of the lingual branch caused no muscular movements,
irritation of one of the small pharyngeal twigs was followed by
very strong convulsive twitches of the throat and lower part of the
face. The capability of this nerve to transmit those impressions
which excite sensation, was amply proved by the severe and un-
doubted indications of suffering which in many cases followed the
pinching of it with the forceps. In several cases, however, the
indications of suffering were much less strongly marked than in
others, but that this nerve possesses common sensation, in the
usual acceptation of that term, I am fully convinced, not only from
the results of these seventeen experiments expressly made upon
these nerves, but from five others, where they were exposed in
displaying the pharyngeal branches of the par vagum. That
irritation of the trunk of the glosso-pharyngeal nerve is attended
by convulsive muscular movements and indications of suffering, is
in direct opposition to the statements of Panizza,^ Dr. M. Hall,
and the late Mr. Broughton,t and is in accordance with those of
Dr. Alcockf of Dublin. I was at first fully convinced that these
experimenters had been operating on different nerves, though it
was difficult to conceive how such mistakes could arise in the hands
of those so much accustomed to researches upon the nervous system.
The details of Exps. V. VI. and VII. will, I think, however, ex-
plain how such discrepancies should arise, without seriously im-
pugning the anatomical knowledge or aculeness of observation of
either party. For though I do not mean to affirm that pinching
the lingual portion of the nerve is never followed by indications of
suffering, (for from the irregularity in the origin of the pharyngeal
twigs, and the difficulty of judging at the bottom of a deep wound,
at what particular part these are all given off, it is generally im-
possible to decide when the lingual portion of the nerve may be
said to begin,) yet I have no hesitation in saying, that if in these
three experiments, and in others not detailed here, we had operated
on that part of the trunk of the nerve which first presented itself,
and not proceeded to dissect it back towards its place of exit from
the cranium, we should have gone away with the impression that
the irritation of this nerve was followed by no muscular movement,
and little if any indications of suffering. Dr. Alcock§ suggests that

* Edinburgh Medical and Surgical Journal, Vol. xlv. p. 86.
t Dr. M. Hall and Mr. Broughton in Vol. iv. p. 679, of British S. Association,
also Mr. Broughton in Vol. xlv. of Edin. Medical and Surgical Journal, p. 429.
ij: Dublin Journal of Medical Science, Vol. x. p. 260.
§ Op. cit. p. 266.

GLOSSO-PHARYNGEAL NERVE. 13

Panizza may have experimented upon the superior laryngeal branch
of the par vagum, instead of the glosso-pharyngeal ; but we can
scarcely believe that an accurate anatomist like Panizza could
commit such an error. Besides, in repeated experiments upon the
laryngeal nerves (as we shall afterwards more particularly mention,)
we found, in all the animals operated on, except two dogs which
appeared considerably exhausted by great previous suffering, ample
grounds for dissenting from the statements of Dr. Alcock, that this
nerve is devoid both of sensibility and of muscular influence.
With the exceptions mentioned, very severe indications of suffering,
and in a few cases also distinct muscular twitching of the neck and
face attended the pinching and cutting of this nerve. These
muscular twitchings, however, were certainly not so frequently
observed nor so well marked as those we witnessed from pinching
the glosso-pharyngeal.

Can these muscular movements attending the irritation of the
trunk of the glosso-pharyngeal nerve arise partly or wholly from
the development of one of those impressions which, when conveyed
by the sensitive filaments to the central organs of the nervous sys-
tem cause some influence to be transmitted along certain other motor
nerves, by which particular muscles are called into action, — in the
same manner as irritation of the trunk of the optic nerve causes
contraction of the iris, and compression of the trunk of the par
vagum in the neck not unfrequently produces violent movements
of the respiratory muscles? Or can it be that these muscular move-
ments depend partly or wholly upon the irritation of the nerve
acting directly through its motor filaments upon the muscular
bundles to which they are distributed, — in the same manner as
pinching of the hypoglossal causes convulsive movements in the
muscles of the tongue ? Dr. Alcock is doubtful on this point.
Though "disposed to regard the result in question as the effect of a
sentient impression excited through the nerve, and referred to the
interior of the pharynx," from the fact, that this movement extends
to muscles not supplied by this nerve, and forms an associated
action, he yet admits, " that the circumstance may be as well ex-
plained by an exalted degree of muscular excitement, or by a higher
one than that necessary to produce the simple starting."* In the
experiments which I have detailed above, we have, however, suf-
ficient evidence to decide that these muscular movements can only
be explained on the supposition that they depend upon some influ-
ence transmitted along other nerves distributed to these muscles,
and through the intervention of the central organs of the nervous
system. We there find, and the facts were still farther confirmed
by what we observed in other experiments, that irritation of a
single pharyngeal twig, or, what is still more conclusive, of the
upper or cranial end of the cut nerve before it had yet given off any
of its branches, was attended by as powerful convulsive movements

* Oper. cit. p. 265.

14 KEID ON THE EIGHTH PAIR OF NERVES.

as when the trunk of the nerve and all its branches were entire and
uninjured.

Is this nerve, then, entirely a nerve of sensation, or is it partly-
motor and partly sensitive?

Mr. Mayo,* and Professor Mullert of Berlin, maintain that it is
both a nerve of sensation and motion, — the former on physiological,
the latter on anatomical grounds. "When the glosso-pharyngeal
nerve," says Mr. Mayo, " is pinched in an ass recently killed, a
distinct convulsive action ensues, apparently including and limited
to the stylo-pharyngeits muscle, and the muscular fibres about the
upper part of the pharynx.'^ I have already stated in the above
experiments that no muscular movements were observed on irri-
tating the lower end of this nerve, when cut across. I attach,
however, little weight to this observation, since it was but rarely
possible to see distinctly the contractions of the constrictors of the
pharynx, from the imperfect manner in which these muscles were
exposed in operating on the living animal. As it is agreed, that
when a motor nerve is irritated immediately after death, and while
the muscular contractility is still vigorous, the muscles to which it
is distributed are thrown into contraction, I proceeded, therefore, as
in the above experiment by Mr. Mayo, to satisfy myself on this
point. These experiments were made upon ten dogs, the nerves
being exposed immediately after death, and the irritation of the
pharyngeal branch of the par vaguTU was always taken as a test
that the muscular contractility was still in sufficient vigour to be
readily excited through the motor nerves, and also a standard of
comparison. I cannot say that the results of these experiments
were uniform, but I am convinced that in none of them was there
any satisfactory evidence to lead us to believe that the glosso-pha-
ryngeal is a nerve of motion ; and I am perfectly satisfied, that in
all of them, which were quite accurately performed, no muscular
movements were seen on irritating this nerve. As the experiment
is one which requires great care in its performance, and is liable to
a marked source of fallacy from the intimate connection of the
nerve with another, viz. the pharyngeal branch of ih^ par vagum,
which is undoubtedly a nerve of motion, I shall relate some of the
experiments which illustrate this. Before doing this I may again
more particularly refer to the relative position of these two nerves
to each other, since this is not mentioned, as far as I am aware, by
any previous experimenter. The trunk of ihe pharyi^geal branch
of the par vagum lies, as we have already stated, quite close to
that of the glosso-pharyngeal. It divides into ascending and
descending branches, the ascending branch (or branches) which
passes to the superior constrictor and muscles about the isthmus of
the fauces, runs generally immediately behind the trunk of the
glosso-pharyngeal for a short distance, and may remain merely in

* Anatomical and Physiological Commentaries, No. ii. p. 11.

t Archives fiir Anatoraie, Physiologie, &c, No. ii. p. 275. 1837, Von Dr. J.

Miiller.

GLOSSO-PHARYNGEAL NERVE. 15

close apposition, or form a free anastomosis vvith it. Very fre-
quently the trunks of the two nerves anastomose by a short branch
a little anterior to iheforame?! lacerum, in which case it generally
requires a careful dissection to show that the large descending
twig of the pharyngeal branch of the par vagum is not a part of
the glosso-pharyngeal nerve. In one case which I dissected lately,
a communicating branch connected the trunk of the two nerves
before they had fairly cleared the foramen lacerum. It is abso-
lutely necessary to have these facts impressed upon the mind,
before any satisfactory experiments can be made upon the glosso-
pharyngeal, with the view of ascertaining whether it is a motor
nerve or not.

Exp. VIII. — T\\e glosso-pharyngeal nej've, pharyngeal branch
of the par vagum, and constrictor muscles of \\\q pharynx, were
exposed in a middle-sized mongrel, immediately after it had been
deprived of sensation by a dose of prussic acid. On pinching the
trunk of the glosso-pharyngeal nerve no muscular movements were
observed; while on pinching the pharyngeal branch of the par
vagum, immediate and powerful convulsive movements of the
constrictor muscles of i\\Q pharynx followed. This was repeated
several times on both sides with the same results.

The same phenomena were witnessed in two other dogs, with
this additional observation in one of them in which the anterior
part of the pharynx was opened, that the muscles about the isthmus
of the fauces as well as the constrictors of the pharynx were
thrown into action on pinching \k\^ pharyngeal branch of the />«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.

<A short view of the knowledge hitherto obtained of the nervous
substance, and of its relation to the organism.

The brain and nerves, which form the organic sensitive system,
or the substance of the nerves, have been, as the peculiar organs of
intellectual energy, early and frequently the subject of deep thought
and careful inquiry. On the one hand, the most acute conjectures
upon the structure and function have been attempted to be made
available ; on the other hand, inquirers have laboured with un-
wearied zeal to unravel by the analytical method the constitution of
this most mysterious of all organs. But the result of all the researches

* Elements of General and Pathological Anatomy. Edin. 1828. Chap. xiii. p. 369.

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 69

hitherto made forms a remarkable contrast between the highly com-
plicated functions, and the remarkable simplicity of the organ. As
we hav^e succeeded in demonstrating in this the existence of a spe-
cies of structure which has been in several respects entirely un-
known, and which is evidently well founded, I think it peculiarly
proper to submit to the Academy a communication thereon, so far
as the subject has been hitherto investigated.

In order to communicate clear ideas on the knowledge and pro-
gress hitherto made, it is requisite to premise a short view of the
previous essential inquiries and opinions. A very valuable history
of the subject in its different departments is given from the more
ancient period, in the fourth volume o( HAWev's Elementa Physio-
logise Humanse ', and in modern times Sprengel's and Hecker's
History of Medicine, and the Biology of Treviranus, as also the
special modern works on the Anatomy of the Brain, by Soemmer-
ing, Cams, Burdach, and others, have given general approximations
of the early and more recent knowledge.*

It is remarkable that the most modern notions upon the nature
of the substance of the brain and nerves have reverted and ap-
proximated to those of the most ancient periods. Already, 500
years before the Christian era, and no historical record ascends to a
higher antiquity than this period, did Pythagoras, to whom the
existence of the nerves, as part of the body, was still unknown, main-
tain the opinion that the brain is the chief seat of the soul, and the
seat of the intellect,! and forms at the same time the reproductive
seminal matter, f which he believed to be a sort of froth from the
noblest parts of the blood. The soul was, according to him, a part
of the sether.

However natural it might seem for every one to consider the
head as the casement of the noblest organ, the Egyptians at that
time held the brain in no estimation, since, as Herodotus shows, in
the process of embalming the dead, it was extracted piecemeal
through the nostrils, and was not treated with attention as the other
organs, and, after being embalmed, replaced in the body. Similar
ideas were at a later period formed among the Hippocratic physicians
of Greece §

These early practical anatomists and physicians recognized in the
brain a body, which they described as cold, spongy, glandular, and
mucous. Hence they formed the medical ideas that the brain serves
to draw to itself the moisture of the economy, and the discharge in
dysentery was regarded as an excretion from the brain by the spinal
marrow. In the treatise of Hipprocrates on Epilepsy, which is

* [It may not be improper to mention, that Prochaska gives, at the commence-
ment of his two treatises, dt Structura Nervorum, and de Functionibus systematis
Nervosi, the best account extant, both as to clearness and accuracy, of the
doctrines entertained from the most ancient periods down to his own times.]

f Diogenes Laert. viii, 30.

X Plutarch, Placit Philosopi, 5, 3. 4.

§ Hippocrates de Glandulis, c. iv.

70 EHRENBERG ON THE BRAIN AND NERVES.

probably spurious, the brain is nevertheless so far recognized as the
organ of the soul, that it is represented to draw to itself the vital
air from the atmosphere.* Perfectly distinct traces of a knowledge
of the true nerves before the time of Aristotle are found in the cir-
cumstance, that it is stated in the treatise mii nim o-ct^a^ one of the
doubtful writings of Hippocrates, that with the two veins, which go
from the brain through the scull to both eyes, the most slender of
the nerves issues from the tough cerebral matter, — thereby indicating
the two optic nerves.t

Plato followed in his view of the brain the doctrine of Pythagoras ;
but, like a poetical philosopher, he embellished it with wonderful
and fanciful appendages.^ From small, triangular, incompressible
smooth atoms the Divinity created the four elements, — fire, air,
water, and earth. By mixing and regulating these last was com-
posed the marrow (^usao?), by which the different sorts of solids of
organic bodies were connected. The marrow of all the bones he
regards as a prolongation from the cerebral medulla^ and the osseous
tissue as the rough covering of the soul, which, for greater security,
are further invested with a soft covering, viz. the flesh. The nobler
part of the marrow, viz. the brain, [to iyMP'XKov\i whose capsule is
the head [xs?*^*)], and in which the divine seed [to fiaov o-jTsp/^t:*]?
should be as in a repository, the Divinity has formed of a globular
shape. The marrow receiving the other mortal intellectual power,
God has created cylindrical and elongated [c^s^^^/xa »«/ Tpof^mn']- The
whole he named marrow, and he so framed the body, that the soul
is attached to it at the same time with hooks, by which he under-
stands the marrow of the bones of the extremities. With the proper
nerves Plato was not acquainted ; and he designates by the word nvgu,
{nervi,) sinews and ligaments.

* Hippocrates. [In this reference Professor Ehrenberg has not stated the
sentiments of the Hippocratic school on the brain so clearly or pointedly as the
text in the treatise warranted him to do. The author of the treatise on epilepsy
says expressly, that the air which is received by the veins or air-vessels is con-
veyed into the cavities and the brain, and in this manner furnishes intelligence
to the head, and motion to the limbs. In the subsequent course of the same
treatise, it is quite clear that the Hippocratic school believed the brain to be
necessary to all the mental functions. To its healthy state the author ascribes
the perception of pleasure, happiness, and mirth, and pain, grief, and distress.
By the brain, he adds, we think and perceive, see and hear, and distinguish the
base from the honourable, and bad from good. And afterwards he adds, that
disorder of the organ produces frightful dreams, panic terrors, and even mental
derangement. In a subsequent passage he expresses a clear opinion that the
brain, by the admission of vital air to the blood is the organ of sensation and
intellect. It is indeed remarkable that it has escaped the notice of medical
archaeologists, that this author has rectified several .popular errors at that early
period prevalent. He, immediately after the passage now quoted, states that it
is quite unreasonable and erroneous to regard the diaphragm as the seat
of thought, and throughout the whole treatise he repeatedly expresses his disap-
probation of the term sacred or divine disease applied to epilepsy.]

f Hippocrates, c. vi.

ij: Plato. Timaeus Editio Bekker. Londini, 1826. Vol. vii. p. 338. The
views of Plato are given at the 48th, 49th, 50th, and 51st sections of this edition.

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 71

' More definite and quite unequivocal knowledge of three nerves
is found first in the writings of Aristotle, the most eminent of
philosophers, and the knowledge of these was also the result of
specific inquiry.* He describes very skilfully the three nerves
of the eye of the fish as three canals of the brain, — a smaller one
lying next the nose, the nervus patheticus of the upper optic hole,
a middle one, which is connected and confounded with that of the
other eye, viz. the proper optic nerve with the Chiasma, and the
longest or largest, which is evidently the superior maxillary
nerve lying in the inferior orbital hole, — the second branch of the
fifth pair. In other respects, Aristotle was aware of the vagueness
of the Platonic doctrine on the organism with regard to the nerves.
He was convinced that the marrow of the bones in the extremities
had no connection with the brain, and that the unciform character
ascribed by Plato to the organ of the soul was a mere fanciful
creation. But the idea, that the soul, if not fire itself, required
nevertheless the influence of fire or warmth to rouse its energy in
the economy, led him also to entertain some doubt on the nobler
active functions of the cold, moist brain. He regarded the heart
as the centre of life, and explained the relation of the brain, the im-
portance of which in the economy was, according to him, self-evident,
by the contrast which Nature herself made known. The heart and
brain, indeed, were, in his estimation, the chief organs of the body ;
but the proper seat of sensation and mental energy he believed to be in
the heart as the centre of animal heat, from which canals proceeded
to all the organs of sense. The brain he believed to possess a cool-
ing property, and to exercise a moderating or tempering influence
on the economy. The spinal marrow he held to be similar to the
marrow of the other hollow bones, and entirely different from the
brain, even opposite to that organ, in so far as it was hot while the
brain was cold. Aristotle also distinguished by the term neura, the
sinews and ligaments, as Hippocrates and JPlato had previously
done.

Though the existence of some nerves as productions of the brain
was at that time unquestionably known, and though their important
influence on the organism was also known, they were not, however,
regarded as organs of sensation. According to the testimony of
Galen, and Ruff'us, the Ephesian,t the discovery of this remarkable
property was first made by the ancient anatomist and physician of

* Aristot. Hist. Animalium.

f The passage of RufFus, the Ephesiati, who probably flourished towards the
end of ihe first century after the birth of Christ, and wrote before Galen, is as
follows. " Secundum Erasistratum quidem et Herophilum sensorii nervi sunt.
Asclepiades autena ipsos sensu vacare testatus est. Casterum secundum Erasis-
tatumcum gemina nervorum {jieuron) naturasit, sensoriorum {aisthetikon) videlicet
atque moventium (kinetikon), sensorii qui cavi sunt, in cerebri membranis
originem habent, moventes in cerebro ac cerebello. Dixit autem Herophilus
aliquos esse voluntate obedientes nervos, qui a cerebro et a spinali medulla
oriuntur, aliquos qui ab osse orientes in os inseruntur, aliquos in musculo in
musculum transeuentes quit articulos etiam copulant.

72 EHRENBEKG ON THE BRAIN AND NERVES.

the Alexandrian school, Herophilus of Chalcedon, by means of ex-
periment. He observed that certain neura communicated sensations,
and others motions. Erasistratus, who flourished at the same period
in Syria, established or made at the same time the same discovery.
It is remarkable that Eudemus of Rhodes is mentioned among the
discoverers ; so that it appears that all those Greek physicians had
derived their information from the same oriental source. Herophilus
found that the sensitive neura always proceeded from the brain or
spinalmarrowjbut the 726 wra of motion went from the bones or muscles,
and were again united to similar bones or muscles. He also believed,
according to Galenas account, the posterior curvature of the upper
ventricle to be the seat of sensation. According to the same author,
indeed, Praxagoras, the instructor of Herophilus, must have known
the final terminations of the arteries as the organs of sensation, but
not for genuine nerves. The same Praxagoras had also represented
the brain to be a useless appendage to the spinal marrow,* and con-
sequently had no clear conception of its true function. That Erasis-
tratus had distinguished the true nerves into nerves of sensation and
nerves of motion is also ascertained, and he further taught that the
nerves of sensation were hollow, and arose from the membranes of
the brain, while the nerves of motion issued from the substance of
the brain and cerebellum.

At that ancient period the poetical hypotheses of the philosophers
were already abandoned, and some proportion of detailed knowledge
of the nature of this new and important organic system was already
developed by the physicians with considerable rapidity.

Galen had, in the second century after Jesus Christ, a very
comprehensive knowledge of the brain, t He maintained with great
certainty the brain to be the probable seat of the intellect, particu-
larly for this reason, because it is a simple and likewise a more
organic elementary body ; and the nerves he represented to be the
seat of the soul. He taught that the nerves issuing from the brain
are soft and nerves of sensation, and those issuing from the cere-
bellum, are firm and devoted to motion. The pairs of nerves pro-
ceeding from the brain and spinal marrow he describes accurately
and circumstantially. He distinguishes in each cerebral nerve,
though this is true only as to the optic nerves, three substances, — an
internal medullary matter, a delicate investing membrane, and a
thick external membrane. The action of the brain he believed to
be an inspiration and expiration of the vital spirit. Fibrous structure
he designated as a predominant character of the nerves, and the
nervous fibres he regarded as hollow.

After the time of Galen, with whose death began the dark ages,
anatomists had indeed occupied themselves eagerly, especially during
the fruitful sixteenth century, with the investigation into many
individual and yet unknown nerves, and their connection with the

* Galenus, ed. Kuhne, iii. 625, 671.
t Galenus, ed. Kuhne, Vol. xiv. p. 710.

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 73

brain and the diffeaent organs, and also with a more particular
topographical description of the brain ; but the opinions of the more
accurate anatomists began to be divided upon the several views
entertained on the nervous structure. Berenger of Carpi discovered
in 1520 that the cerebellum furnished no nerves of motion, but even
no nerves, and that all the cerebral nerves issue from the brain.
Vesalius at the same time drew the distinction between the medullary
and the cortical part of the brain, Volcher Koyter* observed in
1573, that the nerves consist of fibriform medullary fibres {fibrse
capillares,) in the brain from the j»ea mater, which, at their emer-
gence from the cranial holes, are covered with the dura mateVy
and thought that the fibres of each nerve were originally invested
in so many thick bundles, as in their course branches went off from
it. No nerve consists of one individual filament. Fallopius con-
tradicted in 1600 the statement, that all the nerves are covered by
the dura mater, which is peculiar only to the optic nerves. Du
Laurens of Montpellier ascertained at the same time that no cavity
can be distinguished in the nerves, and that the division of the
nerves into those of sensitive and motific is not applicable to the
sixth pair, viz. the nerves of voice, which exercise both functions.
The absence of manifest cavity in the nerves, Vesling also established
in the year 1647, but still regarded the nerves as vessels and canals,
which were filled with whitish medullary matter.

These and many other researches on the more correct knowledge
of the substance of the brain and nerves continued in the state of
uncertain opinions and conjectures, till the discovery of the micro-
scope furnished inquirers with a new organ, as it were, by which
they were enabled to penetrate more deeply into the nature of their
structure.

Leeuwenhoek, whom zeal and keenness of apprehension entitle
to the character of the founder of microscopical anatomy, was oc-
cupied most eagerly towards the close of the seventeenth century,
with the investigation into the true structure of the substance of the
nerves in their various forms. His observations, indeed, are not
made with such circumspection that they could be employed as a
basis for physiological deductions, because the requisite previous
knowledge was wanting ; but they do not deviate so far from truth
as the predominant representations of the most modern times.
What Ruysch had discovered by delicate injection of the cerebral
vesselSjLeeuwenhoekestablished by directmicroscopical observation,
namely, that the cortical matter of the brain consists only of blood-
vessels,

" Between the brains of large and small animals," says this
accurate and laborious micrographer, " there is no other difference,
unless that the large mass of the for.mer is composed of a greateir
number of parts. And when I examine most carefully the vitreous
or cortical substance of the brain, that appears to me in general to

* Coster, Observat. Anatom. p. 107.

74 EHRENBERG ON THE BRAIN AND NERVES.

consist of no other parts than an incomprehensible multitude of
minute vessels."

" Proceeding to the parts of the brain which are called medullary,
I lighted there on some irregular globules of different sizes, almost
equalling the globules of the blood, and which consisted mostly of
thin translucent and oily matter. These globules seem to constitute
the greatest part of the brain. They communicate the white colour,
and appear to be interwoven by threads in the manner of net-work.
Between each mesh of the net-work lay a body in the shape of a
ball ; and I regard the net as the vessels of the medullary matter,
and the balls as globules. The remaining medullary parts consist
of an infinite multitude of most minute globules, and a sort of a clear
thin substance ; and the last 1 conjectured had exuded from rup-
tured vessels, and also that certain vessels had coalesced into the
aqueous matter."

" Upon advancing further, I detected in the cortical parts of the
brain an immense numbei" of very slender blood-vessels. Each of
these almost I observed to open again into minute branches ; and I
observed besides a great multitude of globules, the size of which
was one-sixth part of one globule of the blood. I fancied to myself
the globules now mentioned, encountering vessels so small that
passage through them was resisted, to be necessarily divided into
other parts still smaller, and that such vessels were void of colour."*

From these passages, it appears that in the medullary substance
of the brain, Leeuwenhoek further found, besides the vessels, also
large oily globules of the size of the globules of the blood, which
formed almost the whole of its substance, and of which he inferred
that the colour was white, from their refracting the light. These
globules or vesicles he saw connected as a net by means of threads,

* Leeuwenhoek De Structura Cerebri epist. Deltae, 1684. Op. ii. p. 38. Inter
cerebri grandium et parvorum animalium nullum intercfedit aliud discrimen — nisi
quod magnitude illorum conflata est ex majori numero partium. Et cum accura-
tissime examino vitream (corticosam) substantiara cerebri, videtur ilia mihi in
universum constare ex nuUis partibas aliis, quam ea ineomprehensibili multitudine
minimorum vasculorum.

Perductus ad cerebri partes quae raedullosae audiunt, incidi ibi in quosdam
irregulares globulos diversarum magnitudinum — (sanguinis globulum fere
asquantes) — quique — maximam partem constabant ex tenui translucida et oleosa
materia. Hi globuli — videntur maximam cerebi partem constituere. Caussantur
colorem album— apparentque mihi per fila retis modo esse contexta — Inter quodlibet
foramen retis corporis — pilae forma adjacebat. Reti comparo vasa medullos8&
substantiee — pilae globulos. — Restantes medullosee partes constabunt ex infinita
multitudine minutissimorum globulorum et quadam clara ac tenui materia, quam
ultimam conjiciebam ex ruptis vasculis manasse, necnon quaedam vasa quoqu©
in aqueam materiam confluxisse. — P. 34.

Ukerius progressus — deprehendi in corticosis partibus ingentem numerum
tenuissimorum vasculorum sanguiferorum. — Videbam singula fere vascula iterura
dehiscere in ramulos : praeterea notabam magnam multitudinem globulorum,
quorum magnitudo erat 1-6 pars unius globuli sanguinis. — Imaginabar mihi
modo memoratos globulos vasculis tam angustis, ut transitus iis negitur, oc-
currentes, in alias minores partes dividi necesse habere et talia vascula colore
carere, &c. — P. 34 and 35.

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 75

and in the meshes of the net the globules now mentioned. The
rest of the medullary substance was further many very small globules,
with a scanty transparent matter, which he regarded as exuded from
the small vessels, as he also believed that some vessels terminated
in it.

Leeuwenhoek further recognized in the cortical matter ramified
blood-vessels, which were subdivided into vessels still more minute,
and besides, globules one-sixth of the diameter of the globules of the
blood, and he concluded that the blood-globules, when they arrived
at a smaller branch of the vessel than their diameter, were divided.
He recognized vessels which were still too narrow for the s-^ot^i
part of a blood-globule in the fowl, and the ^^jth part of a blood-
globule in the sheep, and calculated that if a grain of sand were
divided into 64 million parts, still such a minutely divided atom
would be too large for the finest vessels of tlie brain.

These earliest observations of Leeuwenhoek were made on recent
brains, and are in many circumstances in unison with the observa-
tions which I propose to communicate. Upon the direct connection,
nevertheless, observed by him between the ramified canals convey-
ing red blood, and the colourless and unramified canals of the brain,
Leeuwenhoek has been very much deceived, and by obscure and
erroneous theories upon the blood and the mode of ramification of
the blood-vessels, he has been led into a wrong route, in which he
has continued to wander more remotely from the true exposition of
the structure of this substance.

Thirty years after, viz. in 1717, when an old man, as he says
himself, Leeuwenhoek repeated these researches on the substance
of the brain.* But his communications at this period are less
valuable. His observations also were made not on the recent brain,
but on the dried substance and thin slices of dried cerebral matters-
According to these, quite unnatural and distorted phenomena of his
designs are given by a painter. What he took for blood-vessels
may as well be mere folds, ridges, and furrows, which had been
formed by the coagulation of the cerebral substance. — Op. I.
Epistolse Physiolog. p. 309. et seq.

Leeuwenhoek was, however, more fortunate with the micro-
scopical examination of some of the individual nerves than with
that of the cerebral substance. Already had he in 1674 described
the structure of the optic nerve in the eye of the ox. He found no
optic canal in its centre, but saw that it consisted of a fibrous
vascular substance. These fibrous vessels he saw filled with slowly
moving globules. In the optic nerve of the horse he found the
same transparent large globules which the brain presents in the
vicinity of the spinal marrow. He first mentions, in the year 1715,
that he had observed some days previously, that the muscular nerves
in animals are composed of 4 — 20 threads. Though not only in-

* Leeuwenhoek says, " Ita ut mihi jam imaginer nervum hunc opticum copiam
vasorum globulis completorum in se continere," Opera iv. p. 103.

76 EHRENBERG ON THE BRAIN AND NERVES.

dividual nervous threads are hollow, but all are provided with many
cavities, still it may be proper, he admits, to repeat these observa-
tions. He does not well perceive how so much fluid as the nerves
are wont to furnish can be propelled through them. In the year
1717, he mentions that he had observed directly the cavities of the
nerves in a cow, but he could show them to no one, as they at once
dried. There might be about 100 vessels which formed a single
nerve, and although their cavities were very small, he had seen still
smaller living animals in water, [not in the canals themselves,]
which easily moved therein ; (the figure of the transverse section
which he gives is ideal.) A regular motion of fluid or circulation
is not manifest in the nerves. In the nervous threads he saw some-
times also blood-vessels, — veins and arteries (?), the most delicate of
which no longer conveyed blood. The spinal marrow he found in
various points agreeing with the nerves in structure, but always
very confused. In the nerves of a lion, like a ha.ir in thickness, he
calculated the number of canals at 1000. Since the time of Leeu-
wenhoek, the observations of Delia Torre, Monro, and Fontana
attracted to the structure of the nervous substance particular attention,
which was so m.uch the greater, as these observations were more
laboriously, more circumstantially, and evidently more carefully
performed. But unfortunately, all the three observers, as they
examined with similar apparatus quite the same substances, and yet
announced quite opposite and completely irreconcilable results,
essentially obstructed the progress of this species of knowledge.

The observations of Delia Torre by the microscope, which con-
sisted of small self-formed glass-globules, and embraced a very
narrow field, propagated the erroneous representation that the brain
is a pulpy mass, which consists of granules mutually united in rows,
floating in a tough transparent fluid. These granules vary in size
in the different parts of the brain and nerves. The establishment of
this viev/ was long powerfully aided by the confirmation afforded
by the intelligent Prochaska, who only differed in this respect, that
he represented the nervous globules as of the same size everywhere.
This representationwasotherwiseveryfavourable to the philosophical
idea afterwards propagated, in which the great object of search was
one material simple fundamental substance, of which the organic
substances might be composed; and exactly in this central point
of the organ of the soul did that simple substance most closely con-
nected with the mind agree with the ancient Platonic principles.
It was recognized as such in the embryo, and in the lower animals
it was believed to be the only simple substance met with. To these
views recent observations have furnished insurmountable obstacles.
With equal detriment did the observations of Monrooperate, who
taught that he had seen in the brain by the microscope, by transmitted
light, serpentine, twisted, solid fibres, which composed the whole
substance not only of the brain but of all the other parts of the body.
The observations were quite correct ; but instead of inferring from
them that the solar light when it passes through any delicate tissue,

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 77

always occasions the appearance of contorted fibres, he rather con-
cluded, from want of dexterity in the art of observing with the
microscope, that the nervous matter, with which he accidentally
began his observations, is the individual fundamental element of all
organs, viz. skin, nails, hair, plants, and even the metals, earths, and
salts. He subsequently discovered his mistake, and regarded the
phenomena as the result of optical illusion. (A. Monro, Observa-
tions on the Structure of the Nervous System.)

Much more circumspect, though not more fruitful in results,
were the observations of Fontana, which were first published in his
work on the Poison of the Viper. Felix Fontana, the meritorious
naturalist, and Director of the Natural History Museum in Florence,
was in England in 1779, at the time at which the celebrated
Alexander Monro explained orally and taught publicly his views
and observations, and requested of Dr. Monro, in writing, a more
circumstantial statement of his important discovery, as he himself
had the idea of making known certain results of his own. But he
received no answer. Forthwith this conduct accelerated the publi-
cation of Fontana's observations, of which the chief results were the
following.

First he demonstrated that the banded external appearance is a
general character of all nerves, and a phenomenon produced only
by the undulatory disposition of the parallel fibres of the nervous
investment or neurilema. In the interior of the nerves he saw the
matter consist of parallel threads, which he denominates Primitive
Nervous Fibres, {Cylindres Nerveux Primitifs.) The parallel
fibres of the superficial layer which serve for the covering of the
nervous fibres he names tOrtuous cylinders, or spiral fibres, and
ascribes to them a thickness of y^^^^ part of an inch, or about the
ToV^ V^^^ °^ ^ line, (p. 206.) In the rabbit he discovered quite dis-
tinctly that the primitive fibres of the nerves were delicate cylinders,
which appeared to be formed of a thin membrane, and partly to be
filled with a transparent yellowish fluid, and small globules or dis-
similar corpuscles. His figure, nevertheless, corresponds so little
with the clearness of his language, that the observation may itself
not have been clear. Farther, by subsequent researches, as he at
the same time mentions, upon these observations, he had again
become doubtful, and although he very distinctly and accurately de-
scribes the nervous fibres as small tubes with contents, yet the final
description of the same is again incorrect, in so far as he states that
each individual primary canal of the nerves is enveloped in a sheath
by numberless spiral fibres. Lastly, when we inspect the figures
to distinguish in them solid cylinders, no trace of a cavity and
medullary matter is observed.

The medullary matter of the brain consists, according to Fontana,
of a vascular substance, which lies in convolutions like the intestines,
and is surrounded by globules ; and in this bowel-looking substance
there appear several round or obtuse-looking corpuscula. Some
portions of the bowel-like substance, he says, particularly the
m 8

78 EHRENBEKG ON THE BRAIN AND NERVES.

thicker portions, appear ramified, others seem to terminate in round
bodies. In every case he had ascertained that the medullary substance
consists not simply of blood-vessels, and also that it is not composed
of mere globules, but that it is a substance formed of intestine-like,
incurvated canals.

The same structure, though still more delicate, he distinguished
in the cortical matter of the brain, and surrounded with still more
globules also in the retina of the rabbit. All these intestine-like
tubes described by Fontana are evidently the elastic, contracted,
articulated canals of which I am afterwards to speak.

The magnifying powers employed by Fontana were very great.
He employed a magnifying power, which increased the object from
700 to 800 diameters. If his eighth figure, which magnifies the
object 800 times, and is represented 6 lines thick, is rightly taken,
the primitive fibres of the nerves, as observed by him, must have
been ^^3 part of a line thick, which corresponds with the fact very
well.

Though the observations of Fontana were, generally speaking,
correct, yet, as none of the four substances examined by him were
known in their true shape, this prevented other philosophers from
taking the same view, and these laborious researches were not
received, and the discordant results of the observers already named
had thrown suspicion on the use of the microscope, and had con-
tributed to the discovery of a fact now first known, but which
should long before have been known and applied to practice, as it
was now a century since mankind were in possession of the powers
of the microscope.-

G. V. Cuvier, Soemmering, Gall and Spurzheim, Reil, Treviranus,
Meckel, Tiedemann, Cams, Burdach, Mascagni, and many other
celebrated men, had indeed evinced a sufficiently lively interest in
the study of the minute structure of the brain ; but Treviranus
declared that he never took up without apprehension that instrument
which had already imposed upon so many observers. In this
distrust of their own powers by these meritorious observers, it may
be important to know, that after a long-continued use of this im-
portant instrument, which alone can bring us to a S37stem of physio-
logical knowledge of the human body, in some degree satisfactory,
only now for the first have I been able to arrive, through trials
cautiously pursued with increasing confidence, at an entirely new
representation of these subjects.

The most recent period, instead -of contemplating methodically
on a solid basis the organic processes of the mental energy, continues
to advocate two contrary opinions upon the cerebral structure, both
of which are nevertheless erroneous. Barba, and with him many
distinguished modern observers, continue to sanction anew the view
given by Delia Torre and Prochaska of granules in a viscid fluid ;
while, on the other hand, equally celebrated and meritorious inquirers
maintain, that they have recognized no granules, but merely fibres,
as the fundamental substance even to the cortical part of the brain.

KNOWLEDGE HITHERTO OF THE NERVOUS SUBSTANCE. 79

Some others hesitate between the two opinions. Here then we find
in general established in physiological writings, among the simplest
organic parts of the body, either cerebral globules, or cerebral fibres,
or a cerebral tissue or web. Those who maintain the fibrous structure
have been contented mostly with examining the substance of the
brain after induration by spirit of wine and similar agents. Others
have contemplated the radiating and streaked fibres here and there
visible by the naked eye, and feeble magnifying glasses ; and dis-
regarding the idea of Plattner and Soemmering, that the nerves
consist only of solid threads, which are surrounded and filled with
vital fluid by the arteries, exactly as a silk cord is rendered electrical,
anatomists have agreed much in this, that the cerebral substance
which forms the internal part of the brain, is enveloped in the nerves
by membranous cylindrical canals, and that further ^ contents
of the cylindrical canals is connected with, and is one he same

with the brain. In consequence of these recent results of the
researches of Treviranus, the whole brain ought to consist of nervous
medullary matter.

[The most recent microscopical observations on the minute
structure of the brain and nerves are those by Mr. Bauer, and of
which Sir Everard Home has given a sujOficiently minute account in
two Croonian lectures, — one read to the Royal Society on the 7th
December 1820, and published in the Philosophical Transactions
for 1821, the other read to the same body on the 20th November
1823, and published in the Transactions for 1824.

The first object in the nervous system submitted by Mr. Bauer to
the field of his powerful microscopes was the optic nerve and retina,
the latter principally because it was regarded by Sir Everard
Home as " the only expansion," that is, the only expanded form
" of medullary substance in the body." Mr. Bauer found the optic
nerve to consist of many bundles of extremely delicate fibres con-
nected together by means of a jelly-like, transparent, semi-fluid,
viscid substance, easily soluble in water. The dimensions of the
globules measured by the micrometer are from -a^g-W to toVo parts
of an inch, with a few of ^^'•^^, the latter being the size of the red
globules of the blood deprived of their colouring matter.

The retina appeared like a continuation of the bundles composing
the optic nerve, consisting entirely of the same-sized globules con-
nected into fibrous lines, and forming bundles which radiate from
the end of the nerve towards the circumference where they almost
disappear, and terminate in smooth membrane.

Besides the jelly-like substance connecting the component glo-
bules, Mr. Bauer found the whole retina interwoven with innumer-
able blood-vessels, both arteries and veins ; and when the membrane
and part of the nerve was soaked in water for three or four days,
the soluble jelly-like matter disappeared, leaving the globules and
the blood-vessels, which, when separated, formed a delicate net-work
by the free mutual anastomosis of their branches.

This jelly-like, viscid, colourless, transparent matter, which Mr.

80 EHRENBERG ON THE BRAIN AND NERVES.

Bauer found in the optic nerve and retina, he also recognized in
the brain and nerves in general, in which it also forms the means
of connection of the globules, or a sort of basis to the organization
of the nervous system. Its colourless transparency renders it in-
visible, while the substance of the brain is recent, or if it be immersed
in water ; but if the water evaporate and the substance becomes
dry, the jelly-like matter collects round the globules and fibres in
considerable quantity, or forms irregular flakes of various sizes in
the glass, to which it adheres firmly. It issaid to be highly elastic,
and it is coagulated, and becomes opaque on immersion of a portion
of brain in alcohol, — a circumstance from which it may be inferred
that it is albuminous in chemical constitution.

If a portion of brain is cut off" quite fresh, and before being put
in water laid on a dry glass plate covered by another hollow plate
to pi^event evaporation, there exudes a colourless aqueous fluid, which
evaporates on exposure to air, leaving hardly any stain on the glass.
This seems to be merely the watery part of the albuminous connect-
ing jelly.

Mr. Bauer found by placing thin slices of the medullary part of
the brain on a glass plate previously ijioistened with water, and
allowing water to run over it when held obliquely, that the medullary
matter became broken, and there were brought into view innumer-
able loose globules, many fragments of fibres consisting of single
rows of globules, and bundles of fibres, in some instances of con-
siderable length. The globules now mentioned, which are accord-
ing to the figures perfectly spherical, vary from 24*00 to 40V0 part of
an inch in diameter, but the predominant size is rioo part of an inch.
They are semitransparent, of a white colour, arranged in rows so as
to form long threads or fibres, which are aggregated into bundles.
They are held together by the elastic transparent albuminous jelly.

In the gray or cortical matter of the brain, besides the two con-
stituents now mentioned, Mr. Bauer found a fluid resembling the
serum of the blood, of a yellower tint than the fluids in the medullary
substance or any other part of the brain, and when dried assuming
the glassy appearance, and cracking as serum does when dried on
glass. From these facts it may be inferred that this is also an
albuminous fluid, but containing a fawn or buff'-coloured colouring
matter.

The parts now mentioned, 1. elastic transparent viscid jelly, 2.
globules, and 3. aqueous albuminous fluid, colourless, or of a fawn-
coloured tint, are with blood-vessels the essential or fundamental
constituents of cerebral and nervous matter ; and the chief differences
presented by the different divisions of the nervous system depend
on the different proportions in which these constituents are combined
in each.

Thus the cortical or gray-coloured substance of the brain and
cerehellum, that is, the convoluted matter of the former, and the
laminated or foliated of the latter, consists chiefly of globules from
33V0 to 40V0 part of an inch in diameter, the smaller globules being

KNOWLEDGE HITHERTO OP THE NERVOUS SUBSTANCE. 81

most numerous, of a large proportion of the jelly-like elastic viscid
substance, and the yellow or tawny-coloured albuminous fluid, while
the blood-vessels are small but numerous. In the white cerebral
matter, on the contrary, the large globules from jrgo to Woo of an
inch predominate ; the connecting jelly is more tenacious but less
abundant in proportion to the globules ; and the latter are more
distinctly arranged in rows, so as to constitute fibres and form a
fibrous-looking structure ; while the arterial and venous branches are
larger than in the cortical or gray matter.

The mesolobe or corpus callosutn contains the greatest proportion
of the large globules, (24V0 of an inch,) and the viscid jelly is said
to be at least equal to the globules in quantity. In the crura cerebri
and peduncles of the cerebellum the jelly is said to be in greater
proportion than the globules, and the fluid part generally is more
abundant. The annular protuberance {Pons Varolii) is composed
chiefly of globules of the average size 32V0) with abundant viscid
matter, and with the fibrlform arrangement less distinct than in the
medulla oblongata. In the restiform processes, the pyramidal
bodies and the olivary eminences which form the part so denomi-
nated, the fibrous structure consists chiefly of the large globules,
(■20V0 to 2Wo of an inch) with abundant viscid jelly, which is rapidly
soluble in water.

In the spinal chord itself, [medulla spinalis,) Mr. Bauer found
the globules of from 24V0 to 32V0 of an inch predominate, and the jelly-
like basis and fluid to be less tenacious, but more copious than in
any other part of the brain. To this circumstance Sir Everard
Home ascribes the difiiculty of discovering the globular structure
in the spinal marrow : for if the part be not sufiiciently soaked in
water, the fibres cannot be separated ; and if macerated too much,
the whole is dissolved In a mass like cream.

When the brain by immersion in alcohol is hardened, the elastic
viscid jelly is coagulated, and rendered opaque, and the appearance
of globules is no longer perceptible.

Whatever may be the ultimate fate of these observations, having
been marie by an observer, both skilful, expert, and of great re-
sources, they deserve assuredly to be more generally known to
physiologists than the memoir of Professor Ehrenberg would allow
us to believe they are. They do not accord in all their details with
the results obtained by Professor Ehrenberg. But they approach to
them in two circumstances, ^r5/, in the general fact of a globuliform
or bead-like arrangement In the cerebral and nervous fibres, and
secondly, in assigning to the globules a size varying from 20V0 to
30*00 part of an inch. The existence of the interior cavity is the
chief point of difference ; and that, so far as the description of Mr,
Bauer goes, is rather a negative than a positive circumstance.]

82 EHRENBERG ON THE BRAIN AND NERVES.

SECTION II.

Observations on the articulated tubular structure of the brain
and spinal marrow of man and animals, and on the absence
of nervous medullary matter in both.

Certain of the observations here communicated I have already
made for a series of years. But as the results were very different
from the views hitherto taught, and a clear connected account of the
tubularcerebral structurehad not been given, I refrained from publish-
ing them, that I might not, by precipitate and confused statements,
impair the confidence in the aid of the microscope. Recently,
however, as the philosophical views of very meritorious persons,
who still recognize in the brain a primary animal substance, in
connection with my own desires to trace the boundaries of the
organization in the bodies of Mammalia and Man, have recalled me
to the study of this subject, and led me to investigate at the same
time the structure of the whole elementary tissues of the body, I
have thought it preferable to confine my present attention to a full
and minute account of the most important of these tissues, though I
have collected upon several of the other subjects various interesting
experiments.

a. VIEW OF THE MODE OF PROCEDURE.

The results now submitted are not derived from one or a few
observations, but embrace nearly the whole range of the nervous
system, both as a direct inquiry into the structure of many individual
parts of one and the same nervous system, — and as an analogical
comparison of the same structure in the different classes and orders
of organic bodies. The materials from which the conclusions were
drawn were the following.

1. In the human subject 21 representations of the nervous matter
from of an equal number of different places.

2. Of twelve different mammiferous animals 84 representations,
namely, from the dog, horse, hare, rabbit, mole, hog, sheep, roe,
bat, calf, porpoise, and squirrel.

3. Of seven kinds of birds 39 representations, namely, the com-
mon fowl, the crow, the goose, the pigeon, the little bittern, the
kite, and the starling.

4. Offour kinds of amphibious animals 17 representations, namely,
the gray frog, the green frog, the water-newt, and the adder.

5. From eleven fishes 43 representations, namely, from the torsk
(Gadus Callarias), the viviparous blenny, the Gobius niger, the
herring, the Labrus lineatus, the sixQWohd^ck {Gasterosteus pun-
gitius), — all from the North Sea ; further, from the pike {Esox
Lucius), the eel, the karausch, the river perch, and the red-eyed
carp {Cyprinus erythrophthalmus .

STRUCTURE OF THE BRAIN. 83

6. From the class of crustaceous animals 14 figures, viz. from
the river-crab, the lobster, and the crab of the Baltic.

7. From the Mollusca class 5 figures, viz. the red-necked garden
snail, and the marsh snail.

8. Prom the insect tribe 3 figures, from the rhinoceros beetle ;
and

9. Among the annulose animals 12 figures from the leech.

' The whole of the figures were made immediately after the animals
were dead, and while they were still quite fresh ; and in those from
the human body I have examined the parts as little changed as
possible in frosty weather during winter.

With regard to the further and particular method of examination,
the following information is requisite :

I possessed, in 1833, a microscope manufactured by Chevalier of
Paris, and augmented in power at the establishment of Pistor and
Schick of Berlin, — which, indeed, did not furnish the greatest
attainable magnifying power, but equalled the magnifying power of
that used by Fontana. I had also frequent opportunities of com-
paring the greatest attainable magnifying powers, and have employed
the same to the extent of about 3000 diameters. The greatest
magnifying powers, however, and all great magnifying powers, I
have never employed, for the purpose of tracing the figures. All
the present observations I have preferred making, by magnifying
powers from 350 to 360 diameters, a degree of enlargement which
approaches that which Treviranus had already employed in 1816.
(Trev. p. 131.) My reason for excluding the more highly magnify-
ing powers is the inferior degree of clearness and definiteness of the
inner figure in the same. These, however, I have frequently em-
ployed as means of testing the accuracy of the observations.

For making sections of the brain, I employ a two-edged, very
flat, broad, sharp knife, and draw it in making the motion of cutting.
In this manner are formed the thinnest slices, particularly of quite
recent brains. The thinnest slices thus cut off I thrust with the
needle or the point of the knife on a glass-plate, and cut off per-
pendicularly that part of its finest edge which was least changed.
Should this fail in the first incision, I patiently repeat the attempt
till it succeeds. This most delicate edge of the thinnest slice of
brain I examine immediately with the microscope, without water
and without pressure ; and then place on it a very thin small glass-
plate, from four to five lines broad, and one-third of a line thick, or
a plate of mica, in order to expand the parts somewhat without
serious change in pressure, and to bring them to the same level.
For this purpose, after trying and comparing the effect of both, I
find mica less suitable than glass. I then urge the glass-plate with
slight but increasing pressure, and compare the operation of the
process. Manifold experience has taught me that the tenacious
cerebral matter adhei-es firmly to the glass in its finest parts, and
that on slight pressure the parts in immediate contact with the glass
are not detached on being impelled forwards, but the middle ara

84 EHRENBERG ON THE BRAIN AND NERVES.

displaced between the touching objects, which effects a most im-
portant disturbing change in the natural arrangement of fibrous
parts, as impulsive pressure by two glutinous plates brings the
parallel threads of a twine or yarn like texture into opposite crossing,
and converts them into a tissue, which furnishes a very different
appearance from the original condition, and leads to erroneous
results. I have therefore also surrounded the section of brain with
water, and remarked that this not only does not derange the ob-
servation, but that it allows us to distinguish the object more clear-
ly, and in a more natural position of the parts, since the water does
not sensiblv dissolve the nervous substance. The same result ensued
with albumen, the water of the anterior chamber of the eye, and
serum. The pressure of the medullary slices sometimes thick,
sometimes the most slender practicable, I have increased even to
laceration ; and at the spots so burst, where all the constituent parts
are wont to lie quite separately, and at the edges, with and without
water, shortly before bursting, generally the most distinct views
of all were obtained. But it is easy to make the pressure too great,
and this crushes the organic structure. Wherever irregular globules
and granules are seen, the organic constitution has been destroyed
by excessive pressure ; and hence it happened that Leeuwenhoek,
and Fontana, and Allen, observed granules and globules. The
gentlest shoving of the glass-plates on each other by very slight
pressure is very particularly destructive. To obviate this incon-
venience, I had already, in the year 1831, proposed an apparatus
for applying pressure without the shoving movement, which at my
request was constructed by Messrs. Pistor and Schick, and which I
mention in my second contribution on the structure of the infusory
animals.*

In the examination of thick nervous chords, as the muscular
nerves, &c., I have alvvaj's previously prepared the recent nerve by
dissecting it clean, and with the scissors cut off a portion fi'om both
ends without tearing. This portion I next divide in the long
direction with perpendicular pressure, without tearing, either by the
sharp knife or with scissors, in order to meet the neurilema more

* This apparatus was subsequently, in 1833, added to the Berlin microscopes".
It consists of a small round brass-box, which maybe screwed on and unscrewed.
In the lower part lies a thick piece of ground glass, which fits with a notch in
one of the edges of a prominent brass pin. On the glass is laid a piece of very
thin ground glass, which in like manner rests with a notch on the same pin, and
projects witti its thickness over the edge of the lower capsule part. When a
slender object is placed between the two glasses, and the upper part of the capsule
is unscrewed, it presses together with its edge the two glasses simultaneously,
with a screwing force easily regulated at will, and without admitting of the glasses
gliding on each other. Somewhat larger is the very similar microscopical press
contrived by Purkinje and Valentin in the year 1834. The best apparatus of
this kind known to me is one lately manufactured by Pistor and Schiek. This
admits of being increased and diminished during the time of making the observa-
tion with two fingers of one hand, an improvement which insures great advantage,
and enahles us to render the microscope perfect by the more secure method of
fixing its parts.

STRUCTURE OF THE BRAIN. 85

easily, and then separate the parts from each other by means of two
fine steel needles, avoiding, with the greatest possible caution, all
laceration, and treat them without water. Similar preparations I
have placed with a glass spatula, and treated with progressively
increased pressure. The same I have then examined under water,
and I have never found that the water had effected the slightest
change on the structure ; but I beheld all more clearly in a more
isolated manner with the water, and, on the other hand, without,
€very thing lying together partly adhering and distorted.

To recognize in a satisfactory manner the nervous medulla in the
nervous tubuli, and the shape of the tubuli, it is necessary to
expand the tubuli by a little pressure, till the mass of tubules to be
examined meet in the simplest possible order. It would be pedantic,
if it be wished to understand the parallel manifest disposition of all
the nervous tubuli, to expect that they should observe the mathe-
tnatieal parallel. They run under and athwart each other ; and the
fibres which at one moment are parallel, are, by the action of the
muscles and the neurilema, not so the next moment, and alternate
the ensuing instant. The pressure of a lint chord is the most
parallel of all to bring into net-like crossings the threads when they
are not stretched. Hence we see much more frequently by the
pressure slightly crossing them '^perfectly parallel nervous tubes,
though the knowledge of the circumstances leaves no doubt, that
we may and must speak of parallelism of the fibres.

To examine the spinal marrow sufficiently I broke off the osseous
canal, and within the canal I cut off at once by scissors, without
laceration, the portions for examination ; or, in the more delicate
animals, as young frogs, &c., I treated the spinal marrow as a muscular
nerve.

[It may perhaps facilitate the understanding of the following
description, if it be mentioned that Professor Ehrenberg describes,
as discovered by him, the following forms of organic structure in
the brain or its parts, the spinal chord or nerves.

1. A set of tubes which present at definite intervals globular or
spheroidal expansions, so as to resemble a string of beads, which do
not touch each other, but have a short communicating space inter-
posed between each bead. To these tubes he has given the name
of varicose, from their resemblance to the varices of a vein, — and
jointed or articulated tubes, because of the slight resemblance to a
set of joints. These tubes, which present to the microscope the
appearance of parallel fibres, he shows by various proofs to have an
internal cavity, and to contain a peculiar matter, to which he assigns
the name and qualities of nervous fluid. They are confined chiefly
to the white matter of the brain.

2. A set of tubes, straight and uniform, without the alternate
spheroidal enlargements, also hollow, and to which he applies the
name of simple cylindrical tubes. These are found chiefly in the
nervous trunks and chords. These are generally larger and coarser
than the articulated tubes ; but in certain points the latter are found

86 EHRENBERG ON THE BRAIN AND NERVES.

to pass into the former, by gradually losing their bead-like enlarge-
ments. These tubes he represents to be distinguished from the
cerebral jointed tubes, by containing in their interior a viscid, white,
but less transparent matter, to which he applies the name of
Medullary.

3. A substance consisting partly of very minute, fine grains, with
some coarser grained matter, disseminated, as is said in the language
of mineralogy, through the fine-grained matter. The latter is entirely
confined to the gray matter of the convoluted surface of the brain,
or the laminated surface of the cerebellum.]

b. STRUCTURE OF THE BRAIN.
a.. The Cortical Matter.

The substance of the brain has been distinguished into a reddish
external cortical matter, already known by the physicians of the
middle ages, — and a white medullary matter placed internally.
The substance of the circumference, or the convoluted part of the
brain, or the cortical matter, consists of a thick, very delicate vascular
net-work, often conveying numerous blood globules, as Ruysch
first observed, but which at its surface is covered with a vascular
net-work, with serpentine tendinous fibres. Besides the thick and
delicate vascular net of the first substance, I saw in the same, next
its outmost edge, and in its most remote circumference, a very fine-
grained soft substance, in which here and there are deposited larger
grains, nestled and imbedded, as is the case for instance in the
capsule of the thymus gland. The large grains are free, and consist
of small granules, which appear to be connected in rows by means
of slender threads to the very fine small grains of the substance,
singly, and wherever their small size, softness, and transparency
allows the observer to be convinced of this disposition. In the
neighbourhood of the medullary substance the fibrous character of
the cortical matter always appears more distinctly, and in the same
substance the blood-vessels are something larger and less numerous.

I have recently taken much pains to trace the final terminations
of the cortical vessels, and ascertained only so much that they become
invisible in a thick vascular net-work. Anastomotic unions I have
not been able to discover, though I have employed the most perfect
means of modern times. But I have ever intuitively observed a
direct relation of the same apparently sheathless, detached granulated
blood-grains (not blood globules) to the nervous matter. If the
smallest ends of the articulated tubes have open mouths, to these,
accordingly, were the smallest granules of the blood-grains fitted
for the purpose of receiving them directly, and serving for the dis-
tillation or preparation of the nervous substance. By what means
the blood-grains escape from the vessels is still uncertain ; but to
find a reason against their exit in the circumstance of no opening
being visible, appears to me not to be a more weighty objection,
than that all organic pores should open and shut periodically, ac-

STRUCTURE OF THE BRAIN. 87

cording to necessity. It is easy to mistake the anastomoses of the
vascular system for those of the cerebral tubes.

/2. The Medullary Matter.

The white or medullary matter of the brain shows still more dis-
tinctly the arrangement of fibres, which pass in the form of direct
and enlarging continuations of the more delicate cortical fibres, which
especially are directed from certain eminences, that is, the linear or
band-like origins of the convoluted surface of the brain, which chiefly
lie in the long direction of the convolutions, — in a radiated manner
toward the basis. These are not simple cylindrical fibres, but rather
resemble, according to numerous careful observations by me, hollow
strings of pearls, the pearls of which are not in contact, but are
united by a canal for a small interval, or they resemble exactly tubes
or canals dilated at intervals into minute bladders. These bladders
or ampullulse of the tubes were known to Leeuwenhoek, who
regarded them as globules of fat, which constituted the greatest part
of the brain. The connecting canals also he has obscurely indicated.
These tubes, uniformly straight, which appear, only in consequence
of the matter being crushed, and the subsequent removal of the
pressure, to be convoluted like the intestines and variously incur-
vated, as Fontana saw, are generally parallel in direction, sometimes
crossing each other. I have four times recognized, in almost num-
berless individual experiments, a ramification in such individual
canals ; but anastomosis I have never observed. In the neighbour-
hood of the base of the brain there are always found between these
bundles of nodulated tubes, individual tubes much thicker than the
rest, as is also the case in the surrounding matter of the ventricles.
In these thicker tubes it is often possible to recognize distinctly an
external and internal boundary of their wall, or they present, besides
their two external boundary lines, other two inner ones, which
enable us easily to distinguish the width of the area of the internal
cavity of the canals. Hence these nodulated linear parts of the
brain can no longer be named either fibres or threads ; but they are

ALTERNATELY ENLARGED, THAT IS, VARICOSE ARTICULATED TUBES

OR CANALS. All doubt upon this arrangement and structure is
removed by the direct transition of the cylindrical tubes of the
muscular nerves into these articulated tubes.

y. Particular structure of the articulated cerebral tubes, their contents and radiation.

The interior of the varicose or articulated cerebral tubes is every-
where perfectly diaphanous, so that they must be regarded as con-
veying only vapour, water, or clear jelly. The milk-white colour
which they present to the naked eye is favourable, therefore, to the
idea that something is contained in the canals ; but the walls present
not only a milk-white colour but a slight degree of turbidity, while
this colour is wanting in the cortical substance, into which the
same walls extend. I have, nevertheless, not been able, though

88 EHRENBERG ON THE BRAIN AND NERVES.

with a 3000 power of linear magnifying to distinguish the agenrt
causing the turbidity, as something granular or peculiar ; and with
the greatest magnifying power! oftener saw no turbidity.* As
the colourless or transparent articulated fibresof the cortical substance
evidently constitute the tips or apices of the fibres of the medullary
matter, and consequently have parietes entirely similar, yet may
have a small internal cavity and scanty contents, — it appears to be
a just conclusion, that the white colour is inherent, not in the
parietes of the tubes, but in their contents. Tearing individual
cerebral tubes, especially the larger, is followed by elastic contraction
of their free ends, which causes chiefly at the nodulated ends the
irregular intestinal-looking aspect, which has imposed on many
observers. Though no discharge is perceptible, this does not afford
proof against the existence of an internal fluid. If a leech, especially
a young one, be cut in two pieces, both cut surfaces contract at once
so forcibly, that in general not a drop of fluid escapes, although there
be enough in the body and the cut surfaces are rounded by it. Like
phenomena of contraction are by no means unusual with practised
comparative anatomists. It is also difficult to recognize|a discharge,
if the fluid be tough and transparent, as this appears to be in the
interior of the tubes. It is also certain that these tubes do not
contain air, because in pressure under water no air-bells escape from
their extremities ; and as the calibre of the inner cavities is seen in
the thicker tubes, the substance which distends them, being very
transparent and tough, is difficult to be distinguished. If that
medullary substance, which is distinctly perceptible in the cylindrical
tubules of the muscular nerves, be denominated nervous medulla^
no trace of such matter is to be recognized in the articulated tubes
of the brain, and only very rarely can a doubtful trace of it be ob-
served in the thicker articulated tubes of the spinal marrow, ar-
ranged at their emergence into the motiferous nerves. The clear
tough fluid, which distends these tubes, is, in consistence, transparency,
and evolution, as different from the nervous medulla of the cylindri-
cal tubes, as chyle or lymph is from blood. I would propose,
therefore, for this transparent, evidently homogeneous, least defined,
much finer, tough fluid of the cerebral tubercles, the peculiar name
of nervous fluid {liquor nerveus, liquor nervosus of Haller,
naphtha in the sense of the fanciful chemical physicians) ; while the
term nervous medulla, medulla nervea is left for the medullary
matter of the tubular nerves, and the medullary substance of the
brain, if it be not more eligible to name it white substance, since
it does not, like the marrow of the bones, lie in a cavity, and in the
spinal marrow it even forms the exterior covering.

If any one still deem the direct course of the articulated tubes
uncertain, because Leeuwenhoek and Fontana saw and delineated

* Care must be taken not to mistake for jointed tubes, the cylindrical tubes,
■which, accidental!}' or shortly after their emergence from the brain or spinal
marrow, have still dissimilar margins. In the former we easily distinguish the
granular medullary matter, which I have never seen in the latter.

STRUCTURE OF THE SPINAL MARROW. 89

the cerebral tubules as convoluted like intestines, such may be
almost completely convinced of the fact without the aid of the micro-
scope, by simple observation with the naked eye, in the fact, that
they behold white streaked lines only, which pass into the gray
substance. These perfectly straight streaks in the brain are often
very distinct, and very strongly marked at certain spots. Upon
the importance of further investigation into this form of structure
for determining the condition of mental energy, no doubt can be
entertained, and much has already been said on this subject in the
writings of speculative anatomists, as Gall had already devoted to
it great attention. But there is still wanting a much more acute
and precise microscopical examination, as a view of the knowledge
hitherto acquired, and its application to physiology.

The larger cerebral tubules of the medullary matter converge
towards, and pass immediately into, the parts of the base of the brain,
where the peripheral nerves arise. Some of the larger jointed-tube
matter appears to terminate in the cerebral cavities, in the walls of
which I found it well developed. Many pass into the spinal marrow,
and thence immediately proceed into spinal nerves. What I have
collected upon this important species of structure, I propose to com-
municate at a subsequent occasion with greater circumspection, and
more multiplied proofs of its certainty. The investigation may be
at once easy and very difficult, — the former by a hasty desultory
glance, — the latter by careful microscopical comprehension. The
subject is the most important in the whole range of physiology.

C. STRUCTURE OF THE SPINAL MARROW.

The spinal marrow has been sometimes compared to an inverted
brain, and the microscopical structure shows that this is well founded.
In the brain, the most vascular, more delicate part lies externally,
as cortex ; the less vascular more nervous part interiorly, as tnedaUa.
This arrangement is reversed in the spinal marrow\ The more
vascular and more delicate part of the latter lies in the centre, and
the coarse medullary matter covers it externally. Both substances
are quite like those in the brain. From the external medullary
matter consisting of coarse-jointed tubes, the spinal nerves im-
mediately proceed ; and the observer may be easily and distinctly
convinced, that the jointed tubes, where they emerge from the
investing dura mater, assume so suddenly the form of nerve-tubes,
that they become thicker, and with less prominent swelling pass
into the pure cylindrical form. These transitions are pretty easily
recognized in the posterior part of the spinal marrow ; and even
there we find in them, though never distinctly, traces of the proper
nervous medulla. Among all the animals examined by me, the
spinal marrow showed most inclined to the tubular form, and to the
medullary structure in the fishes. Yet in them the medullary
matter, and the cylindrical form was found associated with greater
consistence and tension, far more distinctly in the muscular nerves,
m 9

90 EHRENBERG ON THE BRAIN AND NERVES.

SO that an essential difference in structure of the external parts of
the spinal marrow towards the latter is always very clearly manifest.

SECTION III.

Observations on the cylindrical-tubular structure of the nerves,
as different from that of the brain, and upon the nervous
medulla.

a.. Nervous Chords,

The optic, the auditory, and the olfactory nerves, as the three
noblest nerves of sense, are, as has been already justly inferred from
other phenomena, their colour, and their softness, also shown by
microscopical results to be immediate continuations of the un-
changed varicose medullary matter of the brain. All other nerves,
exceptingthe sympathetic in the middleof its course, differ essentially
from the cerebral matter. They contain the fine tubes considerably
strengthened in an altered shape and energy.

All the nerves examined by me, excepting the three above
specified, and the great sympathetic, consist only of cylindrical
parallel-running tubes, normally never anastomosing, about -li-gth
part of a line thick in the middle, — which are the elementary nerve-
tubes or the pi'oper nerve-tubes, which united in fasciculi or bundles
again form larger bundles, which are denominated nerve-chords.
Each individual bundle and the entire chords, but, as I have satisfied
myself, by no means the individual tubes, are surrounded with a
ligamentous vascular covering {pia mater, neurilema). Very
frequently different nervous bundles of one and the same nerve are
connected by means of false anastomoses, because the tubes pass
from one bundle, and run forwards into another adjoining without
coalescence of the individual tubes. These are the plexuses, which
the nervous roots most resemble, and of which the retina in part
forms one. In a very different manner are arranged the ganglia
or nerve-knots, which are by no means simple plexuses of the tubes.
In the divided roots of the majority of nerves, where they issue
from the surface of the brain and spinal marrow, 1 have recognized
between the cylindrical tubes almost equally strong varicose or
jointed tubes ; but the same also I beheld filled with nervous
Tnedulla. Whether these nerves, mixed in the manner specified,
be the sensiferous nerves, and the pure cylindrical tubed ones be the
motiferous nerves, forms a very interesting subject of future inquiry.
Perhaps on this point the microscopical structure may furnish new
means of attaining to satisfactory knowledge ; but I have hitherto
not been able to convince myself that definite tubular nerves, at
greater distance from their origin, are mingled in their course with

CYLINDRICAL-TUBULAR STRUCTURE OF THE NERVES. 91

jointed or articulated tubes. In the sympathetic trunk, I every-
where see fine articulated tubes void of medulla mixed with coarse
cylindrical tubes.

The simple cylindrical unjointed nervous tubes present an essential
difference from the articulated cerebral tubes, especially in this
respect, that their internal cavity is much larger, and they contain
within it a very distinct, less transparent medullary-like matter,
which appears to have been often before observed, but with less
certainty. In recent living nerves, as I have satisfied myself on
the frog, this content of the simple nervous tubes appears like a
medullary, almost coagulated substance, divided in a net-like or
striated manner, consisting of small, sometimes roundish, not quite
regular particles, which by slight pressure may be visibly extruded
from the tubes. On the transverse section of each nerve, this is
forced out of the individual tube by the proper contraction of its
ligamentous sheath, and forms the surface of the thickening of the
end of the nerve which then takes place. This medullary substance,
which is of a white colour, is that which Treviranus, in his pro-
found researches, named nervous medulla, while earlier authors,
as Reil, discriminating less nicely, regard the content of the whole
fine nervous tubules together, as nervous medulla, though, they
still reckoned the general coverings of the last medullary substance
as neurilema. Reil appears not to have known this peculiar nervous
substance. To remove all doubt on this matter, it is good to con-
trast the substance of the optic nerves with that of the other nerves,
which is still very different. Solution of this substance in caustic
alkali gives very incorrect results, since not only the actual nervous
medulla, but also the tubes and all the finer parts, however different,
appear embraced under the microscope. The tubes and fibres de-
veloped in this manner are consequently of as little physiological
importance as those of Bogros, (Ann. des Scien. Nat. 1825, p. 5,)
or the hollow cerebral fibres of Galen and Des Cartes, which were
hypothetical,

[It may be observed that Prochaska has represented, with great
clearness and accuracy, in the 6th figure of his seventh plate, the
divided end of the sciatic nerve, and the projecting roundish tumour
formed by the exclusion of the nervous matter from the nervous
canals by the elastic pressure of the neurilema. This appearance
Prochaska describes as "the medullary matter of that funiculus, or
nervous thread forced out by the elasticity of the sheath, viewed
laterally, and which manifestly consists of mere globules, which
globules, however, are so arranged that they not imperfectly resem-
ble straight lines or filaments composed of globules placed in straight
lines or rows."

Injustice to Prochaska, I think it is requisite to give his descrip-
tion, which certainly I can testify, from frequent personal trials,
comes as closely to the natural appearances observed by the eye
and good glasses, short of the microscope, as it is practicable to do.
" Another investment of the nerves situate without the cavity of

92 EHRENBERG ON THE BRAIN AND NERVES.

the cranium and the vertebral canal may be justly derived from the
]na Tnater, and extends more deeply than the first, as it is given to
the nerves at their emergence from the brain and spinal marrow,
and appears to be continued to their final terminations. This in-
vestment encloses not only the 'medulla oblongata and spinal
marrow, but even each of the separate threads {funiculi) of nerves
thence issuing, as may be seen in the cerebral and spinal nerves with-
out dissection, and externally on removing their cellular tissue. This
covering is so strong in tissue, elastic, yet little expansive, that it
retains with no feeble compression the medullary matter contained
within it, as is showm by wounding a nervous chord in the spinal
marrow itself, when the medullary substance is extruded by the
opening, as the burst resisting from it, like a mushroom." * * *
" Further, not only each of the nervous chords are closely invested
by this covering, but even within their medullary substance are
transmitted many membranous septa or partitions, by which they
are divided into various fasciculi. From this it may be easily
understood that the greater or less firmness of the nerves depends
principally on that greater or less density of investment, and the
greater or smaller number of the sejita insinuated between the
medullary substance."*

Lastly, it is not unseasonable to remark, that Prochaska, among
his queries of points to be still determined, contained at the end of
the fifth and last chapter, sect. ii. of his treatise, places first the
question, "Who can assign the reason why the globular pulp of the
nerves require to be so forcibly compressed within the sheaths
continued from i\\e. pia mater, Xhzi upon cutting across the nervous
chord it should be immediately extruded by the opening, and form
a small prominence \nionticulumque efficiat V^ This shows that
he had repeatedly observed the fact, though he was unable to assign
the reason of it.]

Of the fact that these fibres are hollow, I have in manifold modes
completely convinced myself. In the first place, there may be
distinguished in each tube four parallel lines, two of which form the
external boundary lines, while the inner indicate the boundaries of
the interior cavity. Secondly, it is easy to obtain a view of the
tubes distended with medullary matter, when it is expanded without
any or without strong pressure, — that is, drawn asunder by two
needles. A glass plate is placed on it, and gentle pressure applied,
and we observe the tubes previously filled with medulla quite
empty, while the medullary matter forms at each end a slight swell-
ing. In the third place, I have, by progressive gentle pressure,
during the process of observing itself, been able to distinguish the
progress of the inner substance; ^^nA fourthly, \ have on transverse
sections more frequently- most distinctly recognized the areas of the
individual tubes. Each of these reasons individually, and, ^fortiori,
all taken together, prove incontrovertibly the hollowness of the
nervous tubes.

* Georgii Prochaska de Structura Nervorum Tractatus Anatomicus, Sect. II.
Cap. II. apud Op. Anatom. p. 329. Viennae. 1800.

CYLINDRICAL-TUBULAR STRUCTURE OF THE NERVES. 93

I have further traced with great care the cylindrical tubes of the
motiferous nerves into the cerebral substance, and I have convinced
myself that they are immediate continuations of the varicose or
jointed cerebral tubes, which, at their emergence from the spinal
marrow,gradually lose the varicose shape, by the connecting portions
of the spheroidal or egg-like joints becoming larger, and the whole
at length forming a uniform cylinder. Of this result I have obtained
convincing proofs by great labour, and have at length found that it
is easy to be satisfied of the fact, by the individual articulated threads,
quite similar to the cerebral tubes, being met in their transition into
the simple cylindrical shape in the roots of the nerves without the
substance of the brain. The evidence of this formation was im-
portant, since it determined this point, that the substance contained
within the nervous tubes then first assumes the appearance of dis-
tinct NERVOUS MEDULLARY MATTER, whcu the nervous tubes are
already separated from the brain or spinal chord, but that these
same 7nedulla-heav'ms, tubes, so long as they form part of the brain,
and are distinctly jointed or varicose, present a perfectly translucent
limpid interior without medullary matter. This also shows that
the jelly-like, milk-coloured granular content of the ultimate nerve-
tubes is not the cerebral matter invested by a neurilematic canal, as
Treviranus represents in his valuable Treatise, but it is a peculiar
nervous medulla, which is either entirely different from the brain,
the fine tubes of which are completely translucent, or is present in
it in another far more transparent form than vapour, or of a tough
homogeneous viscid fluid, as Fontana already regarded it. Conse-
quently, the brain is manifestly comparable to a system of capil-
lary VESSELS FOR THE PROPER NERVES.

. In consequence of these results, I have been at some pains to
inquire, whether the apparently coagulated substance, which is
medullary after death, accumulated in certain spots, and wanting in
others, does not form in the nervous tubes during life a continuous
granular fluid, and, like the blood, is subjected to circulation, the
hypothetical assumjjtion of which appeared necessary to physicians
for a long period, till Alexander von Humboldt's intelligent and
delicate experiments confirmed Rail's h)'pothesis of nervous atmo-
spheres, and supplanted these notions. My experiments, so far as
they have gone, on the nerves of living animals, have proved to me
the existence of no circulation ; and it was equally denied by Leeu-
wenhoek. But whether Leeuwenhoek had observed obscure traces
of a circulation, when he speaks of seeing motions in the canals of
the optic nerve of the eye, is uncertain. This subject, as a physio-
logical one of the greatest importance, and quite within reach, I re-
commend to thejoint labours of scientific inquirers for determination,
especially as it is not very easy to bring under evidence the results
of my observations. The mere precipitate affirmation for or against
these is of no avail. The doctrine of nervous atmospheres, admitted
also by Meckel, may naturally be compatible with the circulation,

9*

94 EHRENBERG ON THE BRAIN AND NERVES.

as this still does not alone elucidate the phenomena of mental energy.
Circulation is not directly necessary.

Among the three jointed-tubed nerves of Sense, the auditory
nerve deserves especial mention. Almost everywhere I have found
the simple tubes of this nerve considerably thicker than those of
the others, and also the spheroidal enlargements, though they were
everywheredistinctly seen, were flatter andsomethinglessprominent.
In other respects it was like the other two. I am, from this re-
markable circumstance, therefore, enabled to distinguish the sense
of hearing from those of smell and sight, because it presents several
remarkable phenomena. Thus sometimes in asphyxia it preserves
its energy, while the whole of the other vital functions are extinct,
and its impressions are far less generally defined, nay, it is the
coarsest of the three. With the detailed observations on to the
nerves of taste I am still in arrear, and will not speak with con-
fidence. The knotted or jointed arrangement appears indistinct.
In the hypoglossal and glosso-pharyngeal nerves I observed only
cylindrical tubes.

b. TERMINATIONS OF THE NERVES.

With regard to the terminations of the nerves, I may be permitted
to direct attention to what appears to me an observation not unim-
portant. I have already mentioned that I have observed in the
cortical substance of the brain, (gray matter of the .convoluted
surface,) with the vascular net-work and the delicate cerebral tubes,
next the surface, an irregular free layer of colourless large globules,
which probably also Leeuwenhoek distinguished, but which has
been passed over by recent observers. Quite similar large granule?
have been long known as constituent parts of the retina, and here,
in connection with a very thick net-work as the division of the
arteria and vena centralis, while the retina itself is the free end of
the optic nerve. Of the existence of similar globules, also, at the
expansion of the olfactory nerves in the nose, I have satisfied my-
self. Comparative anatomy observations taught me that in Sala-
manders {Triton,) frogs, and toads^ the grains of those parts of the
peripheral cerebral terminations are considerably larger than in the
other vertebrated animals, and in man. Since, then, these reptiles
differ from the other vertebrated animals, and from man also, in a
far more considerable size of the blood globules, while the cerebral
substance is constituted quite similarly, a direct relation is thus
closely established between the granules of the retina, &c. and the
magnitude of the globules of the blood. In frogs I have further
remarked, that the blood-globules found in the blood-vessels in the
brain and the retina, frequently in single rows, appear much smaller
and paler than those of the rest of the vascular system, and have
actually lost a part of their wing-like coverings. I am therefore of
opinion, that the perfectly decolorized globules of the retina and
other similar parts may be excreted from the vascular system —

CYLINDRICAL-TUBULAR STRUCTURE OF THE NERVES. 95

probably" as grains immediately emancipated from the blood-
globules, to whose relative size, and whose composition from still
smaller globules, they come very near. The surface of the cerebral
terminations is probably, therefore, the single point in the whole
organic system in which we may recognize with some definiteness
the depositions of globules of the blood. Whether a further internal
development of these blood granules, presumed to be deposited
from the cerebral tubes, which constitutes the condition of their
difference in magnitude, contributes to the perfection and enlarge-
ment of the cerebral matter, or to the preparation of the liquor
nerveus and nervous medulla, and the like, may be subjects of
further research ; but it is already proved with sufficient clearness,
and especially very prominently established by Reil and Soemmer-
ing,* that EVERYWHERE THE NERVOUS TERMINATIONS ARE CLOSELY

SURROUNDED WITH THICK VASCULAR NET-WORKS, the alternate ratio
of which to the nerves has hitherto remained in complete obscurity.
Not at all at variance with such a view I find, in embryos and
young frogs, the easily observed development of the cerebral sub-
stance of a large or coarse-grained form, from which, at a later
period, the cylindrical tubes are first formed.

Several nervous terminations are further distinguished from the
peripheral most delicate parts of the brain, by interspersed mace-
like or even staff-like bodies, the relation of which to the nervous
substance I do not comprehend, though they here and there appear
as terminations of nervous tubes. Staff-like something prismatic
bodies are found in the retina of the frog and fish, club-like bodies
in the Schneiderian membrane of the nose. The largest bodies of
this kind, however, I found in the interior of the ganglions, in
leeches and similar animals ; and I also saw them in the inferior
cerebral tubercles in the snake. If they be detached by pressure,
a similitude in shape to certain forms of seminal animalcules cannot
be distinguished in these bodies ; yet other observations forcibly
withhold me from making a ludicrous resemblance equivalent to a
serious likeness, and I rather avoid it.

I have beien at much pains to trace the ultimate structure of the
peripheral articulated tubes to the vascular system ; but the retrac-
tion of the vascular net-works forms so powerful a source of decep-

* The economy of the larger animals with more powerful vitality presents an
organ left hitherto in obscurity, which in its formation shows structure which
came into my recollection in the course of these observations. It is the thymus
gland of young Mammalia and infants. Draughts which I had sketched at an
early period corroborated my idea, and I have therefore both in man, the calf,
and the cat, observed it again. The resemblance or perfect likeness even of the
granules, which the lobulated thymus-substance, — otherwise formed of the inter-
woven elementary filaments and blood-vessels, — presents to granules of blood of
the same organism, 'is remarkable. Does the thymus gland also remain so long
a receptacle for the grains of the blood-atoms till the nervous system has attained
its full strength and energy ] The similitude of the milk of the calf with the
brain of the calf in colour, consistence, and also in taste, may be also regarded
in the account, as the latter is well known to epicures.

96 EIIRENBERG ON THE BRAIN AND NERVES.

tion, that I feel myself unable to determine the matter. I have
so far, indeed, become convinced that the ultimate anastomosing
vascular branches are considerably larger than the articulated tubes,
still cognizable among them. Numerous branches of blood-vessels
appear further to terminate abruptly without anastomosis, or at least
to withdraw their ends gradually from the power of vision. It ap-
pears that the present instruments, even of the best construction,
form here a limit, which it may be the happiness of futurity to
pass ; but upon this it will not do to judge precipitately. That in
injections no extravasation takes place through the open discharg-
ing branches, forms, indeed, no very important objection which I
suggested, since the anastomoses of the vascular net-work, before
their final terminations, might easily set limits at once to the pro-
pulsive power of the blood, and the injected matter in the net-work,
which the periodical action of the vital economy with instinctive
energy overleaps ; — as the pylorus allows the food to pass periodi-
cally from the stomach into the intestines, or stops it, and then is
considerably dilated and againclosed ; asinblushingand inflammation,
bloodless vessels are alternately filled with blood and discharge it;
and as bile, urine, &c. may be secreted in large quantity, scantily, or
not at all.

(c.) The ganglions and the sympathetic nerve.

The nerve-knots or ganglia vary in their structure. All almost
have this in common, that they consist of accumulations of articulated
or bead-like cerebral tubes, which, either as in the chiasma of the
optic nerves, alone form the tubercle or knot ; — or, as in all the
knots of the sympathetic which I examined, are mingled with large
cylindrical nervous tubules, which are inclosed within a slender
dense vascular net-work, between the meshes of which organ appear
those granules which cover the retina, and meet the ends of the
cerebral nerves. In the ganglions of the spinal nerves 1 saw in
birds, however, only tubular nerves, and very large, almost globular,
irregular bodies, about -5V of a line thick, forming the peculiar en-
largement, which are very similar to a glandular substance, and
which I am almost inclined to -compare to the calcareous sacs of the
frog, which furnish crystals. [These effervesce briskly with acids,
and hence, though the prismatic form of the crystals is strongly in
favour of such a notion, they cannot be phosphate of lime.] I could
very distinctly observe the articulated cerebral tubes of the ganglia,
in tracing their course, to become progressively thicker, and in size
at length to equal almost the nerve-tubes ; yet, so far as I traced
them, they presented always, with more or less distinct articulation,
a peculiar structure, and never attained in size the diameter of the
other cylindrical nerve-tubes. The idea, that the ganglia may be
compared to small brains, is favoured by the knowledge of their
structure ; but the doctrine generally taught, that they were similar
only to the cortical substance of the brain, requires rectification in
this circumstance, that, though the colour is similar, the substance

DIFFERENCE IN THE VIEWS OF OBSERVERS. 97

consists of a mixture of vessels and very slender, scarcely distinguish-
able articulated tubes, [apparently fine-grained medullary matter,]
with true cortical substance, and an excessive quantity of large
articulated tubes with true medullary substance. This cerebral
matter is deposited in round cylindrical nerve-tubes, which are not
changed, but are strengthened by intermixture with the articulated
tubes in ihe'iY fasciculi.

SECTION IV.

Critical remarks on the causes of the difference in the views of

observers.

As we often hear the microscope, that important instrument for
increasing the powers of human vision, blamed and rendered sus-
pected, I have thought it advantageous to subjoin some remarks
upon the probable causes of the discordance in the views given by
observers on the structure of the nerves.

The first observations of Malpighi on the brain previous to Leeu-
wenhoek were very inaccurate on this account, that this great
anatomist of his day raised a great systematic theory on facts im-
perfectly known. His observations also were confined to the boiled
cerebral substance, probably because it was difficult to procure for
investigation the soft natural matter of the brain. He compared
the boiled brain to a pomegranate full of grains, and found in it
glands and vascular sacculi, because he sought for them ; and he
further had the idea, that all the viscera possessed a glandular
structure. I have hence in the introduction not spoken of Malpighi
as a theoretical anatomist.

The difference between the results given by Leeuwenhoek and
those obtained by myself is apparently great : but when accurately
considered, it turns out that he has expressed the fundamental
features of the recent views. He observed in the brain, vessels,
tube-like fibres, and diaphanous globules, though not in their true
connection, but evidently crushed by strong pressure. The sub-
sequent observations made in advanced age, were performed without
sound judgment on the selection of the subject — an objection charge-
able to the observer only. Keeuwenhoek's diaphanous globules,
which were believed to constitute the chief part of the brain, and
to give it colour, which also propagated the notion still prevalent,
that the brain contained many oleaginous drops, which is not the
case, are no deception, but the globular contracted fragments of the
destroyed articulated tubes, and have hence all, as a sure character,
a double boundary line.

Monro was mistaken, when he, without having previously become
conversant with microscopical observation, regarded at once as

98 EHRENBERG ON THE BRAIN AND NERVES.

established the first impression of the nervous substance in bright
solar light. But these statements he retracted, after he had attained
more correct views.

Fontana was mistaken in his inquiries on the structure of the
nerves, when he employed a magnifying power greatly too high,
and hence deficient in light, and which showed him dark tubes, which
he represented as solid cylinders, the outer roughness of which, or
rather indefiniteness of figure, deceived him much.

In examination of the brain Fontana was mistaken, when he ex-
amined portions of the organ not sufficiently finely cut, and not
expanded, or in small contracted portions. It is easy in this manner,
by great magnifying power, to procure the same figures.

The mistake of Delia Torre and Barba consisted in crushing the
cerebral substance between mica and glass-plates, which destroyed
all organic texture, and hence showed only mucus and granules, as
Leeuwenhoek already had seen, similar, but something better.
[Barba, Observat. Microscop. in Cerebr. 1819,]

Observers have recently seen fibrous structure or striated arrange-
ment in the substance of the brain or retina, but have over-looked
the remarkable varicose form of the tubes. The reason of this
mistake I have also been at pains to discover ; and it appears to me
to be in the too low magnifying power, which allows to recognize
in the retina and cortical substance, as more delicate parts, a fine
tissue of solid smooth fibres. Want of light, also in great magnify-
ing power, and want of adequate magnifying power in the case of
much light, operate in this case in like manner in producing the
optical impression of solid fibres.

To quiet the minds of several persons, who, I have learned, en-
tertain doubts on the correctness of the varicose tubes, which they
might regard as an unintentional artificial product of pressure or
water, or any other source of fallacy, I further add, that I saw this
articulated or jointed appearance first without water and without
pressure, and I can allow no influence to either of these two condi-
tions. I remained sometime in doubt on account of the elastic
tension. A tense silk thread falls into wrinkles when its ends are
detached, and the tension ceases. Similar wrinkles might also
appear here, as joints or knots. But increased pressure on the
varicose tubes does not attenuate them to cylinders, though the
slice of brain is thrust completely asunder, and is often entirely
isolated. On tearing the cerebral substance beneath the microscope,
at certain spots, by pressure, very often individual varicose fibres
remain as connecting media of the rent portions, and are stretched
to the lacerating point without losing their articulated form. Second-
ly, we evidently see a totally different effect from elastic contraction
in the same articulated tubes. If they are first extended by pressure,
and then left under the pressure, the articulated tubes, which were
previously rectilineal and smooth, appear incurvated, bent, folded,
and irregularly convoluted like intestines, which is evidently the
peculiar effect of their elastic contraction. It may be further ob-

DIFFERENCE IN THE VIEWS OF OBSERVERS. 99.

served, that the cylindrical tubes of the muscular nerves are equally-
elastic ; but in these the rosary or bead-like form never comes into
view, however small be the portions employed, — any more than in
any other elementary substance in the body ; they are merely
curled at the edges and incurvated, but are still distinctly the con-
tinuations of those which are curled also in fragments.

I formed to myself the idea that the liquor nerveus by the elastic
contraction after the excision of the medullary portions, collects in
knots, and accidentally dilates those places, which constitutes also
their irregularity. This circumstance would then betoken a greater
degree of contractility or elasticity in the more delicate nervous
tubes, the cerebral tubes, than in the coarse, the tube-nerves. But
this also is without foundation. Their pressure does not cause that
presumed accumulated content to change its place ; and in the coarser
canals the dilatations are, in proportion to the diameter, often so flat,
and where the articulated tubes in their transition sometimes contain
distinctly medulla and grains, sometimes equally distinctly are
quite empty, while the narrow canal is filled, that the form of the
tubes, according to my conviction, must be peculiar. But, in what-
ever mode the matter be viewed, the peculiar capacity of the arti-
culated nerves, viz. the cerebral tubes, &c. to present the rosary or
bead-like arrangement continues to form in every circumstance, a
very essential difference from the nervous canals, which seldom or
never appear so.

Some recent observers have been disposed, by circumstances, dif-
ferent from all those specified, to assign to the nervous substance the
character of a granular matter, because they distinctly and correctly
observed actual granules. They have been particularly deceived
by the granular covering of the retina, the atoms of which the
meritorious Meckel names medullary scales. This granular layer,
most anatomists, and recently Arnold, in his instructive Treatise on
the Eye, regarded as the retina itself, which it is not. Generally
the aspect of the retina is perceptibly wonderfully different, and
several observers recognize it by no means as a continuation and
expansion of the optic nerve, which it, however, truly is. That not
the granular layer, but the membrane lying behind it, named serous,
which Ti'eviranus has circumstantially examined, is the proper
retina, is demonstrated in the recent eye of the rabbit, where this
membrane quite distinctly and readily presents the varicose or
bead-like cerebral tubes of the optic nerve. The same appearance
I have at least once recognized in the human eye little changed. In
many other animals I have repeatedly found distinctly the same
structure as in the eye of the rabbit. In fishes we see frequently
these join'^ed tubes of the expansion of the optic nerve running
backward at once in all directions, like white rays, from the place
of entrance of the optic nerve through the sclerotica. In the eyes
of many other animals, this radiation is, as in man, less distinct to
the naked eye ; but in the rabbit, the hare, and some other animals
they are prevalent in two directions. The fine-jointed tubes, which

100 EHRENBERG ON THE BRAIN AND NERVES.

cause the radiating streaks are, however, arranged otherwise,
arranged as striae or streaks. They are not all equally divergent
from the centre, as the radii of a circle, but they form everywhere,
as is most easily seen in the rabbit, a nervous plexus, in which the
articulated tubes run obliquely to the circumference, intercrossing
each other obliquely.

In short, though the retina requires to be investigated still more
accurately than it hitherto has been, my view of its structure is at
present the following. The retina is a cerebral substance, formed
principally by expansion of the optic nerve, — which is covered and
penetrated by a thick vascular net-work, in the meshes of which
is found anteriorly a thick layer of free grains, which consist of still
smaller granules, and have the greatest similitude with the granules
of the blood. In some eyes, for instance in those of the frog and
fishes, but not in the human eye, I further recognized staff-like, or
mace-shape corpuscula, in the circumference of the retina (not in
the centre), the connexion of which with the nerves and vessels
continued obscure. Whether the nerve-tubes themselves end in
this, it is impossible to determine.

The articulated substance of the retina only, as I understand,
consists, like the brain itself, of two parts, — one a very fine gray
substance, articulated, so far as is known (cortical substance), and
the other a more distinctly articulated white substance (medullary
matter). The latter is close to the optic nerve itself, and its fibres
are distinct continuations of the same. These forms of structure
can be distinguished onl}^ in quite recent eyes, not kept beyond a
single night.

Arnold gave in 1832 a very different explanation of the structure
of the retina, in so far as that which I term retina or reticular mem-
brane, he considers as a mucilaginous layer, and a cellular tissue
connecting the granules, as nervous matter. My discovery of the
connexion of the jointed tubes of the retina, with the perfectly
similar tubes of the optic nerve, has further corroborated the above
view. Particular chords of the sympathetic nerve, which, accord-
ing to Ribes, are wont to enter with the central artery and its
branches, and to be distributed with it, which he infers from noso-
logical grounds, I have not been able to distinguish, without dis-
covering impediments to its practicability.

[As Professor Ehrenberg has made no reference to the observa-
tions of Mr. Bauer, as described by Sir Everard Home, it is proper
to mention the following circumstances.

In the second figure of Plate 6, is represented the arrangement
of globules passing without interruption across the cortical into the
medullary part of the brain ; and in this figure there is something
of the jointed or articulated appearance so much insisted on by
Ehrenberg, as characteristic of the jointed cerebral tubes.

In the third figure of Plate 5, the globular structure arranged in
rows, gives the multiform appearance bead-like, though the beads
touch each other, and are not separated so widely from each other as

ESTABLISHED RESULTS. 101

Ehrenberg represents. In this instance, the globules are magnified
two hundred times. It seems therefore not unreasonable to con-
clude, that the chains of globules seen by Mr. Bauer are the same
objects which Professor Ehrenberg viewed as bead-like or uniform
tubes. The intervals given by the latter author are certainly very
large compared with the globules ; but the general character is not
so widely diflferent as at first sight appears.

It is further to be observed, that though in the figures of Plate 4,
the globules are represented as large and touching each other, yet
in figure third. Sir Everard represents a jointed or knotted tube,
which he terms a vein with valves, and which, from its winding
tortuous course, was probably a vein, but which, nevertheless,
bears a close resemblance to the jointed or articulated tubes of
Ehrenberg.

Lastly, with regard to the microscopical examination of the
structure of the retina, it seems impossible to doubt the fact, that
Sir Everard and Mr. Bauer did give a view of that membrane, which
was new at the time, and approaches very closely to the account of
its structure given by Ehrenberg. Sir Everard represents Mr.
Bauer to have found its globules disposed in rows, so as to form
globular chains of fibres, and these arranged in the intervals or
meshes of the vascular net-work, formed by the divarication and
anastomosis of its minute branches.]

SECTION V.

General view of the results of these communications^ with some

consequences.

a. ESTABLISHED RESULTS.
The Microscope.

The compound microscope shows, according to the history, to
all careful observers, the same fact unfolding itself in one and the
same mode, and furnishes the knowledge of substantial facts, which
may be entirely or partly employed as the foundation of further
researches. Of erroneous representations of the objects seen, thougli
these may also be ascribed to the prevailing notions of the time, the
observer, and not the microscope, must always bear the manifest
blame ; and if persons otherwise meritorious have been thereby
misled, the cause, as the history distinctly proves, equally lies not
in the microscope, but in this, that before its employment in research
so minute and intricate organic structure, they did not prepare
generally, and labour urgently to render themselves confident in
the use of instruments ; that they built superstructures on a base
m 10

102 EHRENBERG ON THE BRAIN AND NERVES.

whose foundations were notfixed with sufficient stability ; or that they
wished to recognize the structure of the delicate living brain in the
boiled or indurated or dried organ. The most important assistance
in acquiring more intimate knowledge of the phenomena of organic
life is the compound microscope in the hand of the cautious practised
observer ; and though we frequently continue to recommend and
prefer the simple lens before the compound one, in much stronger
magnifying powers, on account of the transparency, this is because
the advantage of the latter is still not sufficiently generally known,
and not rightly appreciated.

No one who comprehends the extent and intricacy of Nature
will expect that the first observation should give a complete know-
ledge of any one organic structure ; but what the good observer
ascertains by repeated circumspect trial and just exposition, may
then, and ever after be used by his successors as a basis on which
sure steps may afterwards be made. Leeuwenhoek was therefore
a meritorious observer, because the elements of his observations
with very imperfect instruments are at present in many respects
valuable, however incomplete they were. Treviranus was on the
same account the best observer on the subject under present con-
sideration, between the time of Leeuwenhoek and the present.
Uncertainty and want of truth in communication are speedily de-
tected, when the employment of powerful instruments is in general
use, and are much less detrimental than neglect of the application
of means of assistance so important. I trust that the communications
here made, so far as they have gone, may enable us to predict what
is yet to be expected, and to recommend a further cautious use o^
these means of discovery.

THE STRUCTURE OF THE BRAIN.

1. The substance of the brain consists neither of granules nor of
simple fibres, and is in its larger proportion formed after the model
of no other texture, but consists of parallel tubules or cylindrical
canals lying fasciculated upon each other, not altogether alternating,
but with remarkably regular dilatations (varicose or articulated),
from -gV to -joVo pai^t of a line in diameter, which converge from the
circumference to the cerebral chambers and base of the brain, becom-
ing stronger, are united by no peculiar perceptible cement or cellular
tissue, and pass into the spinal marrow, the greater part of which
they constitute.

2. The brain, which in its function is evidently a central organ,
is in its structure, as Gall already knew, a peripheral organ, and
cannot be compared with the heart or stomach as a central organ.

3. The spinal marrow of man and of all the large divisions of the
vertebrated animals consists of articulated, jointed, or geniculated
canals, entirely as the brain. The finest tubules lie internally, the
larger externally, and all the tubules have to each other a predominant
parallel disposition. The outer large tubules are immediately con-

STRUCTURE OF THE BRAIN. 103

tinuous with the cylindrical tubules of the nerves of the spinal
marrow. This constitutes animal marrow {Myeloneura, Medul-
lar ia).

4. The three soft nerves, or those of proper sensation, and the
sympathetic nerves, consist of articulated cerebral canals, which are
surrounded in a fasciculated manner by neurilematic canals (liga-
mentous fibres and blood-vessels) ; and the first of those are immediate
continuations of the medullary matter of the brain. Of the latter
the substance is mixed. This form I designate articulated or jointed
nerves (Gliedernerven).

5. In the articulated tubules of the brain, the spinal marrow and
the nerves of the extremities is found a perfectly transparent tough
fluid, never distinctly granular, the succus nerveus, liquor nerveus,
which differs from the nervous medulla, as chyle does from blood.
A manifest motion of the same is not certainly observed, but a tardy
progress is probable.

6. All other nervous trunks (I examined the whole of the parent
stems) consist not of articulated cerebral matter, but they are
CYLINDRICAL TAscicuLi inclosed by tendinous or ligamentous par-
titions and vascular nets, of somewhat larger tubules, which are
the immediate but suddenly changed continuations, altogether or
almost unarticulated, of the articulated cerebral tubules, and as such
are first surrounded by tendinous neurilema. These cylindrical
tubules, which are known for the largest and most delicate among
the vertebrated animals, are from the ^V P^'^t to the iroo part of a
line in diameter. In the vertebrated animals they are frequently
from -j-i^ to "1^0 part of a line in diameter. They appear under
various forms and in various functions, since they contain in their
interior a peculiar interrupted, granular, as if coagulated medullary
substance, which by moderate pressure mat be visibly forced

OUT OP THEM, AFTER WHICH THEY REMAIN EVIDENTLY AS EMPTY

cases, with INNER AND OUTER BOUNDARY WALLS. These forms
I denominate tubulated nerves (Rohrennerven).

7. The nervous matter as well as the brain consists consequently
everywhere of articulated tubules, void of marrow, conveying
nervous fluid, and cylindrical tubules conveying true nervous
medulla.

8. The brain contains no nervous medulla.

9. A spinal chord of articulated tubules of consistent nervous
matter without medulla is wanting to the invertebrated animals.

Or the INVERTEBRATED ANIMALS HAVE NO SPINAL CHORD, thoUgh

the chain of abdominal ganglions distinctly conveying nervous
medullary matter, and consisting chiefly of cylindrical tubes, may
perform the function of spinal marrow.

10. In the invertebrated animals, which I might denominate
spinal-marrowless {Ganglioneura, Emedullaria), articulated cere-
bral tubes and globules of blood, are cognizable in a smaller pro-
portion.

11. The articulated nerve-tubes void of medulla, according to

104 EHRENBERG ON THE BRAIN AND NERVES.

their proportion to the human organism, and their distribution in
the animal kingdom, constitute the more important and noble part
of the nervous system, ministering directly to sensation.

12. Generally all the cerebral terminations, though in less degree
in the organ of hearing, are interwoven and enclosed with a vascular
net-work increasing in thickness, and contain large disseminated
globules, the size of which bears a definite proportion to the size of
the globules of the blood in one and the same genus of organism,
abstracting from this, that in some animals several elementary parts
are somewhat larger than in others.

13. The structure of the retina has even in man been hitherto
very erroneously described. The granular medullary layer of the
anterior surface of the retina is interwoven with a vascular net-work
from the central vessels, and behind these two lies the expansion of
the optic nerve, which consists of articulated tubes, and is parted
into a peripheral or cortical, and central or medullary substance.
Separate disseminated mace-like bodies and rods appear between
them often to soften the impression of the light. Their connexion
with the articulated tubes of the nerves I have not clearly ascer-
tained.

b. SOME BEFLECTIONS AND CONCLUSIONS.

1. To the brain, according to the estimates of Malpighi and Haller,
uniformly a third part of the whole blood of the body is sent. As
the brain has been hitherto viewed as a pulp of globules, arranged
in the form of solid fibres, it was by no means of consequence to
ascertain this remarkable quantity of blood. Agreeably to the con-
stitution of the more delicate anatomical structures, it is more than
probable that the blood is applied immediately to a principal deter-
minate organic purpose.

2. The blood consists of a tough almost colourless fluid {serum),
and numerous reddish bodies swimming in it. [By this Ehrenberg
seems to understand the Liquor sanguinis of Babington.] Not-
withstanding manifold researches, it has been hitherto impracticable
to assign any admissible purpose to the atoms of the blood, only the
uninterrupted current of the globules of chyle and lymph, and their
wasting rendered necessary a conversion of the former into the
latter, and a consumption of the atoms of the blood. That these
atoms hold the vascular parietes asunder like peas, in order to pave
a free path to the plastic serum, or arrange themselves with care
for the muscular fibres, or remain stationary in certain points (in
the capillary vessels, which cannot terminate, but must be perfectly
retiform), or by arising and ending in vessels without other apparent
object than that of a constant transformation, should simply maintain
an energy therein, are historical opinions on which I touched some-
thing more particularly in the essay read at the Hufeland meeting,
De glohulorum sanguinis usu, in July 1833.

3. The globules of the blood consist, in the vertebrated animals

REFLECTIONS AND CONCLUSIONS. 105

as in man, as Hewson correctly said, of central colourless white
grains, quite similar to globules of chyle, not always of uniform
size, and reddish homogeneous coats. To inclose the grains of
lymph in these coats seems to be one object of the vascular system,
and indeed of respiration. In none of the vertebrated animals, but
in many, probably the majority, of the invertebrated animals, the
coat is detached from the blood-granules.

The grains of the globules of blood consist of still smaller granules
of almost uniform size, which I discovered in the mammalia to be
10^0 part of a line in diameter, but which in the invertebrated animals
are often much larger. These three constituent parts of the globules
of the blood are in the reptiles easily seen, in man with greater
difficulty ; and the grains are less easily dissolved in water than the
coats, — a fact also distinctly taught by the important researches of
John Miiller. The coats of the grains of blood are large in the
reptiles, fishes, and birds, but in the mammalia, especially man,
they are small.

The granular layer of the retina and the nest-like depositions in
the cortical substance of the brain are, according to my views, similar
to the granules of the blood, and by their free situation are a little
more moveable.

4. The quantity of the globules of blood is in the different forms
of organized bodies in a distinctly direct proportion to the quantity
of the articulate tube substance in the nervous system, — great where
the latter is most abundant, and small where the latter is little, —
most in the mammalia and in the human body.

5. A consumption of the grains of the blood globules for the pre-
paration of the liquor nerveus of the articulated tubes in the brain,
&c. is in the vascular system of the terminations not improbable.

6. The nether layer of such medullary grains which resemble the
blood grains is remarkable in the thymus capsule, [which has the
shape of a many-celled many-lobed purse,] previous to the mental
individuality of the child and young animal, and its wasting cor-
responds with the development of the latter. To this analogy I
have been led by the comparison of the cerebral granules. Similar
granules are presented by medullary sarcoma. Is this an anomalous
formation of thymous structure, consequently injuring the organic
life ? [Deposition of grains of blood with subsequent tubes.]

7. According to my most recent direct inquiries into the state of
the living uninjured nerve in the frog, no rapid remarkable motion
of fluid takes place in the tubes ; and there is rather a deposition of
a material very important, as appears, not destined to undergo
further transformation, the white nervous medulla or the colourless
tubes.

8. Investigation on the state of the final termination of the
cutaneous and muscular nerves, which also are inclosed by vessels,
shows no deposition of granules in their vicinity. From this it
may be concluded that there is an absorption of nervous medulla at
the terminal ends of the cylindrical tubes.

10*

106 EHRENBERG ON THE BRAIN AND NERVES.

The ideal figure of an individual nerve-canal is, in my coneeption,
so far as direct observation permits to go, fusiform, with great
slenderness and incipient division beyond the middle, swelling
cylindrically, and carrying medullary matter, then diminishing,
always simple, and losing itself probably among vessels.

I here observe, that I have long recognized the muscular fibres
also, though I do not find them hollow, to be fusiform, because each
separate cross-plaited muscular thread at both ends passes into a
separate slender spiral-shaped tendinous thread. Hence the frequent
fusiform shape, and by reason of the dissimilar length of the muscular
fibres, the tendinous margins of the bellies of the muscles. To
isolate these textures is a very difficult task ; and I give the result
of four years' inquisitive consideration. Whether a similar structure
takes place, as was in the nerves, and also in the canals, it is not
allowed to determine by the present means of inquiry ; and at an
earlier period it must have been still less practicable.

9. Would not therefore, seemingly the nervous energy be a
secretion from the blood of a material, and especially of these
grains ; which first, in the form of tough fluid, is collected in the
articulated tubes, and gradually in that of nervous medulla is ac-
cumulated in the cylindrical tubes, advancing tardily and imper-
ceptibly, till at their ends, it again, as excreted matter, passes into
the general absorption.

The distillation of the nervous medulla from the blood appears
then to be immediately the development of that mysterious mental
process which indicates itself, as sensation, and which, growing
with the growth of the body, augments to complete consciousness.
The circumstance that man, by reason of the extent and the con-
voluted disposition of the largest surface of the brain, presents
consequently the most extensive secretion of nervous fluid, may
bear a direct relation to his mental energy.

SUPPLEMENT.

The foregoing results of my researches were communicated, on
the 23d April 1833, to the Academy, at a meeting of the physical-
mathematical class ; and in order to accelerate the useful application of
the facts communicated, an abstract of it was published in Poggendorfi'^s
Annalen der Physik, Band, xxxviii. 1833. I then extended the
observations in many directions, and wrote a Latin congratulatory
letter to Hufeland, on occasion of his Jubilee, on the 24th July
1833, De globulorum sanguinis usu. A detailed report upon the
same subject, with the above named figures, I communicated to the
general meeting of the Academy, on the 24th October of the same
year. These communications have found many partizans ; and I
think it may be useful to add a few remarks thereon.

Those friends and anatomists who witnessed the phenomena,
forthwith expressed their persuasion, that these phenomena appeared
to them exactly as I represented them. With Professor John

SUPPLEMENT. 107

Miiller, I soon examined the nervous roots in the frog of the separate
sensiferous and motiferous nerves, and the examination furnished
no essential difference in their microscopical structure, as I already
knew. But Professor Krause, in Hanover, speedily added some
other circumstances to the subject. He represented the cerebral
fibres as solid fibrils, and as soluble as water, and the dilated swell-
ings which he also recognized, he regarded as peculiar globules,
which he denominated nerve-globules. I stated the grounds of my
dissent from these views at the same time in the 31st volume of
Poggendorff's Annalen, 1834. Not less different from my repre-
sentation of the matter were also the statements of Professor Berres
in Vienna, which appeared in the Medical Annals of the Austrian
States for 1834. Professor John Mi'iller, however, soon expressed
himself publicly in his Manual of Physiology, from the results of
personal researches, as very much in favour of the general view ;
and there appeared in Miiller's Archiv of Physiology, an essay of
Dr. Valentin, a pupil of Purkinje in Breslau, which accorded with
this view of mine in several important points. He ass\ires us, for
instance, that he observed directly, not only the internal area, and
the internal cavity of the cylindrical tubes, but also the articulated
tubes, of which I, with the means of assistance at my command,
have reason to doubt, though with more perfect aids it is practicable.
The grains of the retina he regards, from their size, as not perfectly
analogous to those of the blood, the size of which is everywhere
very different. He searched for manifest orifices in the blood-
vessels, which, however, appear to be unnecessary, since there are
enough of terminations of branches which discharge freely. The
articulations or joints of the articulated tubes, he considers to be
accidental products, but which, from the above statements, is in-
admissible.

Rudolph Wagner admits, without objection, in his work on Com-
parative Anatomy, the whole of the leading statements made by
me. Professor Volkmann of Leipsic gave lately in his new con-
tribution to the physiology of vision, 1836, a very similar description
of the subject from his own observations ; but he did not distinctly
observe the inner areas of the canals, and thinks with Krause, that
we may have been deceived with the inner contour as in the case
of a hair, — a thing possible certainly with desultory single obser-
vations, but which cannot take place, where the area and progress
of the content, and the fulness and emptiness of the tubes, were
observed and carefully considered. The great softness of the sub-
stance has led him further to take the fragments lying between rent
parts for drops of oil. His figures of the articulate tubes and the
tubular nerves are, even to the less sharpness of the lacerated edges,
and the want of selection of fully turgid tense canals, perfectly
correct, and closely accordant with my views. It results also from
his communication upon the retina of the fish, in which he could
see only pulpy matter, and no articulated tubes, which, however,
he saw distinctly, as I did, in other eyes, that the investigation of

108 EHRENBERG ON THE BRAIN AND NERVES.

the most slender parts of these structure requires longer familiarity
with the subject, as I have already devoted to it. The enlargements
of the varicose fibres he agrees with me in regarding as a real, not
an accidental structure (p. 17), and adduces in support of this satis-
factory reasons drawn from his own experiments. The grains of
the retina he regards as essential parts of that membrane, but confirms
the proposition of similar though not so uniform grains between the
various cerebral tubes (p. 9). In an appendix the author retracts
(p. 198) the statement, that the retina is formed of articulated tubes
after he received the Memoir of Treviranus, and describes the
predominant structure of the retina, certainly not correctly, as
cylindrical fibres ; but in p. 200 he allows again that it consists of
swellings.

I have closely traced these fibres of the retina in the rabbit, and
in several fishes, and I am convinced that they are only the articulated
tubes of the optic nerve. That the articulated tubes have in many
places fewer, in others more numerous, dilatations, should be no
impediment to the more early view ; and their being void of marrow
and filled with white liquor nerveiis,2iS happens to both, distinguishes
first the articulated tubes of the nervous system, and though some-
times the knotty swellings are more scanty in so short spaces, which
may for the microscope be termed long, they are isolated quite
sufficient to impress the character. In like manner, apparent or
even real knotty swellings in the cylindrical tubes, though here and
there though rarely they appear abnormally, or as marks of stages
of development, cannot, however, be admitted as the general pre-
dominant formation. Empty blood-vessels also are not white, but
colourless and diaphanous ; whereas the radiations in the eye of the
rabbit are white, and the canals unramified, which is never the case
with blood-vessels.

Godfrey Reinhold Treviranus, the most eminent biologist of our
time, has, in his last work, Contributions to illustrate the
Nature of Organic Life, again brought forward his opinion upon
this structure, supported on new grounds. After beginning " among
all animal substances, no one requires management so delicate as the
brain," he allows, at p. 29, " that the transition of the medullary
tubes into the nerve-canals is exactly as I have stated it, but in two
important points he is of a different opinion. First, He denies the
reality or constancy of the bead-like arrangement in the articulated
tubes, which, however, is not a fallacy, but accidental, and it ensues
sometime after death. Air and water, he thinks, change immediately
the true shape of the tubes (p. 31). He saw also once the nervus
abducens of a sparrow with articulated tubes, (was it also as regular
as void of medullary matter?) though it be not a nerve of secretion.
All the tubes are originally cylindrical. Secondly, I have not, he
thinks, recognized the nervous cylinders of the cortical matter,
which were, however, distinctly apparent. It may be difficult in
expression to move rightly in structures so minute, and it has
certainly placed only the difference in my preliminary account.

SUPPLEMENT. 109

The figures accompanying this memoir will readily remove all such
doubts. The tubes of the cortical substance I have by no means
denied, or rather the whole substance have designated as a mass of
vascular net-work of very fine cerebral tubes, and heaps of small
granules of blood. In other respects, the articulated tubes, which
are very distinct in the neighbourhood of the medullary substance,
and also at the periphery of the brain, are so minute, that my best
microscope could show the connecting parts of the small vesiculated
joints very feebly, sometimes not at all. I hence believe, that
Treviranus may understand the distinct tubes only near the medullary
substance, while I understand the crossing cylinders, which are seen
distinctly dense at the surface of the brain, not at all as cerebral
substance, but I recognize in these the short, anastomosing, most
bloodless branches of the vascular system, which are also without
trace of vesicular dilatations. As to the articulated form, I must
yet repeat, that all the above assigned causes, inducing a change in
the tubes, are included by me, and that on account of the great
generality of the phenomenon, I must regard it as something
constant and real. As the labour of such an inquirer is always-
rewarded, Treviranus has made a very important discovery in this,
that he has recognized the mace-like bodies in the retina and Schnei-
derian membrane, as immediate continuations of the nerves. The
mace-like bodies themselves have been already long known to me ^
but I was unable clearly to perceive their connexion, and I have at
present no proper, certain element thereon, though I have represented
these forms of structure in several modes in the plates referred to.
Similar, much larger mace-like bodies are found in the brain and
the ganglia of the invertebrated animals, and in some birds I saw
like bodies in the ganglia. From the careful observations of Remak,
which are also published in Miiller's Archives, I infer that he views
the articulated tubes as constant, but saw the cylindrical tubes more-
frequently conveying medullary matter with the advancing develop-
ment of the body.

If the sensiferous roots of the nerves taught by Sir Charles Bell^
and at present generally admitted, but whieh are to me not perfectly
clear, should be fully established, the predominance of medullary
canals in them would be extraordinary, since in the nerves, which
are most clearly devoted to pure sensation, the cylindrical shape
and medullary matter are altogether wanting. A character so definite
would be to me unintelligible. I would rather, in case there are
special sensiferous roots as subject of research, unless they be un-
necessary, so understand the phenomenon, that their elementary
tubes issue immediately from the brain, while the m,otiferous, with-
out evident sensation, proceed from the spinal marrow or the
ganglions. These, however, are fruitless speculatians. We. must
previously observe still niore deeply..

110 EHRENBERG ON THE BRAIN AND NERVES.

EXPLANATION OF THE ENGRAVINGS.

The majority of these figures are true copies of the objects seen, and
indeed not of the first, but the most successful preparations, where the
peculiarities were most distinct.

All these figures are formed, when another degree of magnifying power
is not particularly specified, after one and the same generally an enlarge-
ment from 260 to 360 times in diameter. The largest cylindrical tubes
are magnified 300 times. The figure is sometimes 1^ Paris line in
diameter, consequently the object, when the figure is accurate, is ^i^
part of a line large. The largest articulated tubes in Fig. 2d are magnified
to an equal degree, but two lines broad, and they were ji-^ of a line in
diameter. Such measurements must indeed be always specified, but it is
requisite to avoid pedantic minuteness.

PLATE I.

ARTICTTLATED NERVES, U TO k.

Fig. a Structure of the medulla oblongata. The thickest jointed
tubes -j-^^, finest -joW ^^ ^ ^^^^- ^ Middle medullary substance of the
brain yi^ to ^^^^ of a line, c White matter of the spinal marrow 3^ to
s^ part of a line, d Substance of the olfactory nerves, with some very
thick almost cylindrical tubes, from xto to 4I0 part of a line in diameter.
f Substance of the optic nerves 3^0 to s^o- g Decussation (chiasma
opticum) of the optic nerves from 355 to ^^s part of a line, h Retina with
the medullary grains, articulated tubes aiHio) medullary grains -gio', nucleus
of the medullary grains about aoVo- i Some articulated tubes of the retina
800 times enlarged, k Globules of the blood and their nuclei or granules,
which are much alike in size, and are separable into still smaller granules.

EXPLANATION OF THE ENGRAVINGS. HI

PLATES TI. AND III.

MIXED AND PURE CYLINDRICAL NERVES.

Fig. I Structure of the nervus divisiis, artificially separated from each
other ; thickness of the tubes 3I0 to ^^o- '^ Structure of a vertebral gan-
glion vyith mixed nerve-tubes and some medullary grains, n Structure of
the nervus oculorum motorius, with pure cylindrical tubes, which partly
are still filled with medulla, and partly by pressure, have been emptied
of their medulla in separate points. Thickness 3^0 part of a line.

MIXED AND PURE CYLINDRICAL NERVES CONTINUED.

Fig. 0 The nervus trochlearis as before. The conjoined opening of
the middle tubes is the individual observation of this nature, p The nervus
abducens with tubes mostly emptied by pressure ; thickness 4^ part of a
line, q The facial nerve as before, r The nervus vagus / thickness 4^0
part of a line. [Plate III.] s The hypoglossal nerve, all the tubes filled
with medulla ; each 4^0 part of a line thick, t The glosso-pharyngeal
nerve, still quite filled with medulla, u The accessory nerve, with canals
partly emptied by pressure, v The intercostal nerve emptied by pressure.
X The ischiatic nerve at its roots.

In the most of these nerves the areas of the inner cavity could be seen
at the cut surfaces, y A magnified portion of the recent medullary
capsule, which has been hitherto described as the thymus gland from a
still-born child, with its net-work of elementary fibres, large blood-vessels,
and the medullary substance, deposited quite similar to large granules of
blood.

PLATES IV. V. AND VI.

These are the views given by Sir Everard Home, of the appearances
presented to Mr. Bauer by the brain and nerves.

Plate IV. contains several small parts of glass micrometers, when the
inch is divided into 400 parts in diameter, which divides the surface into
160,000 parts ; so that each object is magnified 400 times in diameter,
and 160,000 times in superficial extent.

Fig. 1. In the first, square at A are represented the most predominant
globules in the brain, 33^00 part of an inch. The other squares contain

112 EHRENBERG ON THE BRAIN AND NERVES.

many loose globules of various sizes, and fragments of bundles of simple
globular fibres of the medullary substance of the recent brain, immersed
in water.

Fig. 2. represents the same objects in a dried state, when the accumu-
lated mucus and some newly produced globules become visible.

Plate V. Fig. 3. A small portion of the medullary substance of the brain
diluted with water, also fragments of single globular fibres, many loose
globules, and a portion of the venous branches with valves.

Fig. 4. A small portion of the retina of the human eye diluted with
water, — consisting of loose globules and globular fibres, of the same size
as those of the brain in its various. parts ; also a branch of an artery whose
anastomoses form a minute net work.

Plate VI. Fig. 1. A small portion of the recent human brain, after im-
mersion in distilled water ; magnified five diameters.

Fig. 2. A smaller portion magnified twenty-five diameters, showing
the arrangement of the globules in straight lines, passing without interrup-
tion across the cortical into the medullary substance.

Fig. 3. A still smaller portion magnified two hundred diameters, so as
to render the globules conspicuous.

PLATES

PROFESSOR EHRENBERG'S MICROSCOPICAL OBSERVATIONS

NERVOUS SYSTEM IN MAN AND ANIMALS.

m 11

Khrenberg. — P/>^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<!t, during the whole time, upon certain muscles.
The anatomical distribution of the cutaneous nerves favours my
notions; for the prone surface receives its cutaneous nerves from
the same nerves as the flexor muscles, and vice versa. Nature has
also distributed to those parts which she has endowed with an acute
sense of touch, an abundant muscular apparatus and great move-
ability; whereas those parts endowed with a less acute sense of
touch admit of no motion per se. (See on this subject, the inter-
esting investigations of Ernest Heinrich Weber.)

This theory does not appear applicable to the mucous membrane
of the hard palate — the sensibility of this part to taste is, however,
probably explicable, that the action of the muscles supplied by the
hypoglossus affect the inervation of this part of the mouth. The
pain of the knee from contraction of the psoge and iliacus, in coxalgia
shows how distant from one another parts may be situated in which
muscular action calls forth sensations. Weber's experiment upon
the acuteness of the sense of touch should be so instituted that cer-

132 STROMEYER ON THE PRODUCTION OF SENSATION.

tain movements could at the same time be performed. Blind per-
sons, in whom the sense of touch is usually so fine, would be par-
ticularly fitted for these e-xperiments.

The case of paralysis related at the commencement of this paper,
of which analogous instances must be familiar to every practitioner,
is a striking contribution to the theory, that the sense of touch in
the skin is increased to the extent of enabling us to form distinct
perceptions, solely in consequence of certain muscular contractions.
Although the lady, in that case, had not suffered the least paralysis
of sensation, as every external stimulus was felt by the paralytic
the same as by the healthy limb, yet, when she rested the body
upon the injured limb, by which the body was propped up to a
certain extent by the bones, she did not feel the sensation of touch-
ing the ground with the foot; on the contrary, she appeared to tread,
as she expressed herself, upon a spring, or upon a bladder filled with
water. She attributed her inability to step out upon the foot to this
abnormal sensation. Some may say that she was conscious of the
impotence of her muscles, and that this consciousness was derived
from the sensation felt by her in the sole. This is correct, pre-
cisely as by over-contraction of the psoas and iliacus pain at the
knee is produced ; with this difference, however, that the above
explanation is an empty sentence, instead of a physiological exposi-
tion. The patient had not that inervation of the cutaneous
nerves which arises from the contractions of the muscles.

Violent exertions (such as long walks) induce less pain in the
muscles than in the joints, on which the peripheral extremities of
the cutaneous nerves are distributed. After over-long walking, we
use frictions of the ankle and knee-joints ; for these latter, and not
the muscles, appear stiff" and painful. After rubbing some time we
feel reinvigorated, through some beneficial operation upon the sen-
sitive nerve being communicated by reflexion to the muscles. The
activity of numerous muscles obviously increases sensibility upon
a larger scale. The erect posture alone produces increased frequency
of the heart's action ; walking and more violent exercise do so still
more. Epileptic convulsionsdo not invariably accelerate the motions
of the heart : this affords a satisfactory proof that augmentation of
sensibility is the cause of increased action of the heart during violent
exertions, for it is well known that during epilepsy the perception of
organic as well as animal sensations is diminished, or even annulled.
From the phenom.ena of epilepsy, therefore, we must, for the most
part renounce the notion that violent exertions and standing excite
the heart merely mechanically.

The organs of generation are endowed with a sensibility dif-
fering from common sensation. This peculiar sensation is, in the
male, concentrated in the glans penis ; in the female, in the clitoris.
As the muscular power of the clitoris possesses evidently no impor-
tant mechanical object it is very probable that the musculus erector
clitoridis has been imparted to the organ for the same reason that
the immoveable muscles have been given to the human ear — namely

PRIAPISM. 133

to enable volition, or the imagination, to act upon it. If the excita-
tion which produces erection be mechanical, the first impulse must
evidently come from the nerves of sensation ; but if the imagina-
tion excite the generative organs, the first impulse can only take
place through centrifugal nervous currents, and these necessarily
in motor nerves. This leads to the conclusion that in the male, to
whom the property of erection has been given not merely for the
purpose of exciting venereal feelings as in the female, the first
impulse of the imagination aflfects the ischio and bulbo-cavernosi
muscles, and that through their contraction the impediment to the
reflux of the blood is produced ; without which, notwithstanding
Mueller's interesting discovery of the arteriae helicinae, erection
cannot be conceived to take place. The activity of these muscles
excites the sensibility of the parts of generation ; this increased sen-
sibility reoperates upon the muscles, and thus the erection is con-
tinued and increased until excitement, augmented to the highest
degree, produces a fresh reflex motion — ejaculation. Priapism is
the excess of erection — tonic spasm and neuralgia. Erection essen-
tially depends upon the combination of increased inervation of the
sensitive nerves of the external parts of generation, and of the motor
nerves of the ischio — and the bulbo-carvernosi acting reciprocally
upon one another. Contractions of the same muscles, induced by
other causes — for example, irritations in the urethra or bladder —
produce spasm, but in general no complete erection. We can post-
pone for hours the necessity of voiding urine, even to the length
of producing paralyses or inflammation of the bladder ; but with
the desire to void it, the contraction of the detrusor ensues, which
we, nevertheless, are not able to contract voluntarily. It is probably
the same with the bladder as with the ear ; the influence of volition
upon its muscular fibres is not adequate to the production of volun-
tary contraction, but it suffices to augment the sensibility of the
sensitive nerves, to the extent that the stimulus of the urine in the
bladder reaches the sensorium, by which a reflex contraction of the
detrusor is induced. In like manner, perhaps the imagination is
able to produce evacuations of the bowels — by the administration
of homoeopathic remedies for example.

The combination of motor and sensitive phenomena extends
undoubtedly to the viscera supplied by the sympathetic system ; and
to this is attributable the apparent concensus of mucous membranes
with distant sensitive nerves, evidenced for example, by the itching
of the nose through the irritation of worms. We are well aware that
pll the nerves of the senses are intimately connected with the chy-
lopoietic and adjuvant viscera, and amaurosis arises very frequently
ex abdomine. The most approved remedies for such derangements
are antispasmodics, tonics, and laxatives, the object of which is to
restore the secretions, which have been disturbed, not by inflam-
mation, but by a perverted action approaching to spasm. Who
would be inclined to attribute the disturbed secretions merely to the
sensitive parts of the sympathetic, and not accuse its motor filaments

134 STROMEYER ON THE PRODUCTION OF SENSATION.

to an equal, if not greater degree ? Irregular or morbid actions of
the muscular tissues of the abdominal organs form the combinations
with the nerves of the senses, which, in the case of the eye, lead to
amaurosis, — in the ear, to deafness. Both these complaints are fre-
quently preceded for a long time by hyperassthesis, intolerance of
light, or noises in the ears.

Numerous, it is true, are the other abdominal causes of these
affections of the organs of the senses. The characteristic lumbar
pains of delivery, which are present chiefly during the contractions
of the uterus, or at least are then considerably increased, confirm
my views. I allude to the pains in the loins, and not to those of
the extremities, as it might be presumed that the latter arose from
pressure of the uterus upon the nerves of the lower extremities',
whereas the trunks of the cutaneous nerves of the lumbar region
arise too high to be pressed upon. It is clear that pressure upon
the nerves is not the cause of these pains, because they may be
relieved by pressure upon the lumbar region itself, by means of a
pillow or the hand of an assistant. Pressure upon the trunks of the
nerves could, it is true, produce the sensation of pain in their peri-
pheral extremities at the loins, but the peripheral extremities them-
selves would necessarily be insensible, and therefore "no pressure of
the pillow at the loins could be serviceable.

In a similar manner, pressure diminishes for a time the purely
symptomatic headaches ; in tic douloureux, however, the locality of
the pain is not so adapted to the application of pressure as the sur^
face of the cranium or the loins. The pain in the back coincides'
regularly with the contraction of the uterus ; therefore the action of
its motor nerves is combined with augmented sensibility of the sen-
sitive nerves of the lumbar region. On the other hand, I wouM
suggest the use of frictions of the loins, with liq. ammoniae caust.
&c. in lingering labour, in order to accelerate the pains, by reflexion.
If the contractions of the uterus be the cause of the lumbar pains^
through the combination ofmortor and sensitive nerimus activity ^
we may draw an inference from them of the condition of the uterus
during the convulsions of lying-in women. Instead of the activity
of the motor nerves of the uterus being primarily increased, it is the
sensitive nerves, which are inordinately excitable, and their irritation
consequently acts through reflexion upon the general muscular
system.

The question, in what manner the neuralgiae are explained accord-
ing to this doctrine of the combination of nervous activities, must
have already forced itself upon the attentive reader of the above
pages. It has been long recognized in the explanation of spasm, and
Marshall Hall has distinctly expressed his opinion to the same effect,
that both of the agents of nervous activity must co-operate — the
sensitive nerves for the reception of the irritation, the motor nerves
to reflect it to the parts susceptible of contraction. I know not
whether a similar principle has been advanced in explanation of
neuralgias ; at any rate it is not generally adopted. Indeed, these

NEURALGIA. I35

painful aflfections have ever constituted one of the most mysterious
chapters of pathology, in the discussion of which we are usually
dismissed with empty, though high-sounding sentences.

It has latterly been believed that neuralgias are local organic
diseases of the sensitive nerves, or of the immediately adjacent
structures, — a belief that was supported by occasionally finding
exostoses and other tumors pressing upon the nerves, and in some
cases enlargements of the nerves themselves. The presence of these
tumors, however, does not explain a characteristic peculiarity of
neuralgias — the sudden accession and disappearance of the pains,
comparable only to electrical discharges, and without the superven-
tion of any cause cognoscible to our senses.

It is scarcely conceivable that so violent a local irritation can exist
without reflexion in the motor nerves ; nor is it probable that the
alternating innervation of the painful nerves can occur without being
connected with spasmodic contractions of some muscles, no more
than a cramp can arise without previous affection of the sensitive
nerve. After every amputation, the cut ends of the nerves enlarge
into pestle-shaped tumours, but they are only in few cases accom-
panied by a painful state of the stump, which we are obliged occa-
sionally to reamputate. Pressure purposely effected upon the ulnar
nerve produces a continuing pain, but no alternating attacks. Be-
sides, then, the local irritant, a second agent must be in operation.
We are led at once to seek this second agent in a combination with
spasmodic contractions.

If the pain in the knee of coxalgia be the consequence of a con-
traction of the psoae, which the patient does not feel in the muscles
themselves, just as the lying-in woman does not feel the pains in the
uterus, it follows that this second agent of neuralgias cannot be re-
cognized by the sensorium. We may therefore cherish the hope,
that by careful observation, and with the aid of the theories of
reflexion and combination, we may succeed in discovering the
seat of these spasmodic contractions, as we have done the cause of
the knee-pain.

The connexion of neuralgias with abominal affections has long
since attracted the attention of practitioners : they resemble in this
respect the hypersestheses of the nerves of the senses, but differ
from the latter by the cruel peculiarity of not passing so readily
into torpor and paralysis, the cause of which it is not difficult to
perceive. The curative means of neugralgias appear to be those
capable of acting upon both agents of the nervous activity.

We not only seek with the aid of narcotics to diminish the
excitability of the sensitive nerves ; we endeavour also by means of
tonics to blunt the irritable parts against the occurrence of spasmodic
contractions ; and thus, according to that which I have advanced,
both classes of remedies have in the end the same object — to inter-
rupt the combination between motor and sensitive nerves, which
has developed itself to excess. If the most efficient and most fre-
quent cause of neuralgias did not consist in the excessive reactions

136 STROMEYER ON THE PRODUCTION OF SENSATION.

of these combinations, instead of the existence of local diseases of the
sensitive nerves, would not paralysis be much oftenerthe consequence
of neuralgia than it is? It is, on the contrary, known that they can
make the whole course of a man's life wretched. The frequent
paralysis of the portio dura through slight inflammation in its neigh-
bourhood, shows that much is not requisite to paralyse a nerve dur-
ing an organic morbid process. It is true that there are neuralgias
in which the peripheral extremities of the nerves, in which the
patient imagines that he feels the pain, are paralysed and insensible
when touched. In such cases we may with a degree of certainty
infer the existence of a local disease of the trunk of the nerve, from
which diseased and excited spot the centripetal currents of nervous
influence proceed.

It will, I think, be easy to conceive, by means of the doctrine of
combinations, why the division of neuralgic nerves is so seldom
productive of benefit ; why the pains are seldom limited to single
trunks, or follow their anatomical course ; why new branches are
effected when the excitability of those first attacked is exhausted,
or when they have been cut through. For the combination of mo-
tor and sensitive filaments are infinitely numerous, nervous trunks
are only juxtaposed nervous filaments, and the motor agent is usually
beyond the reach of the surgeon's knife.

I cannot deny myself the satisfaction of illustrating my theory
by a neuralgia, in which it can be demonstrated that the first impulse
of the pains proceeds from the motor agent. I allude to neuralgia
of the testis, termed by Sir A. Cooper irritable testis. This neuralgia
differs from many others in the circumstance that it vanishes by
absolute rest of the patient upon the healthy side. The patients,
therefore, generally sleep well, and setting aside the almost absolute
repose in which they are forced to continue, they suffer no essential
disturbance of the general functions. The affected testicle is some-
what swollen, hangs a little lower than the other, and there is a
constant urgent necessity of supporting it. The slightest motion,
standing or walking, produces the most acute pains, not only in the
testicle, but also in this skin in the neighbourhood of the inguinal
canal. The disease may be sometimes relieved by the ordinary
remedies of neuralgia, and by issues in the inguinal region, or it may
require castration, by which it is radically cured. The section of
neuralgic nerves is, as I have before mentioned, a very dubious re-
medy ; as, therefore, castration is successful in neuralgia of the testis,
it follows that the cause of the disease is situated at no great distance.
The appearance of the pains upon the slightest motion, particularly by
rising upright, or by walking, shows that the action and stretching
of the abdominal muscles which contribute to support the trunk
erect, have some connexion with the production of the pains. The
contraction of the abdominal muscles narrows the inguinal canal.
In incipient inguinal hernia the tumor appears when the patient
coughs or stands up, by which the power of contraction of the
inguinal canal is diminished in the proportion that the impulsion of

IRRITARLE TESTIS. I37

the intestine is increased. The mere diminution of the abdominal
cavity by pressure upon the bowels will not cause the appearance
of the hernia. The contractions of the inguinal canal are not felt
by the spermatic cord in the healthy condition of the parts, and
even a very tight truss may be worn without pain in the cord.
But if the contractions of the canal occur spasmodrcally, which,
owing to its muscular structure, is certainly of very probable
occurrence, for all muscular parts are subject to spasm, the spermatic
cord will be inordinately pressed upon .in its entire circumference,
constituting one source of pain, and, on the other hand, through
augmented activity in the motor filaments of the nervous sperma-
ticus externus distributed to the parietes of the canal, and increased
centripetal current of nervous influence in the sensitive portion of
the N. spermaticus internus, indicated by pain felt in its peripheral
extremities, in the testicle, will take place.

Thus increased irritability and cramp constitute the circle which
keeps up the patient's sufferings — a torture removable at will by
avoiding every motion capable of exciting the inguinal canal to
contraction. The slight swelling of the vessels of the testis, and
its hanging lower than the healthy gland, may be mechanically
explained, the one state from pressure upon the veins, the other
from pressure upon the motor nerves of the cremaster, which are
given off in the canal. Castration cures this disease, through the
cord subsequently shrinking and receding in the canal. I am of
opinion that neuralgia of the testis may as readily be cured by
slitting open the external parieties of the canal, exactly as the
painful spasm of the sphincter ani is cured by division of that
muscle. I should not fear giving rise to the production of a
hernia after the operation, for the cicatrices of muscles and tendons
are very firm, and the object of the incision would not be to enlarge
the area of the canal, but to cure the spasmodic disposition of the
muscle. It is unnecessary to stop here to explain how far the
application of my views will serve to elucidate the origin of hernia
humoralis.

In neuralgia of the testis the affected motor and sensitive nerves
lie in anatomical and physiological relation, very near to one
another, and the motor agent is accessible to the knife ; in neuralgia
of the face, the motor source lies to all appearances deeper, and
most probably in the abdominal viscera. Nevertheless we may
apply the experience gained by the observation of a process going
on comparatively superficially, to the study of those more deeply
seated, just as the phenomena of external inflammations are success-
fully applied to the elucidation of those internally situated.

In concluding my observations upon the law of combination,
with its application to a practical subject hitherto so clouded, I am
far from believing that I have adduced for its fundamental confirma-
tion any conclusive evidence.

I do not doubt that hecatombs must be sacrificed to the genius of
modern physiology, before the correctness of my theory can be
m 14

138 STROMEYER ON THE PRODUCTION OF SENSATION.

considered fully demonstrated. I am not deficient in the spirit of
invention necessary for experimenting upon animals, but I have
not the inclination needed for their execution. I willingly leave
this part to the physiologists by profession, whom I must, however,
remind, that, " irritation of a motor organ, by mechanical or
other means, does not induce increased currents from the
central organs of the nervous system, towards the spot irritated,'^
but only from the irritated spot of the nerve downwards : and for
this it is indiiferent whether the muscular fibres themselves or their
nerves be irritated. " /n order, therefore, to cause currents to
emanate from the centre, reflex motions must be produced ;''^ for
they alone, like the emanations of the will, are combined with
centripetal currents in the sensitive nerves. Irritation of motor
nerves will never produce such combinations, as the nervous currents
in the motor nerves are only centrifugal.

As I only consider this short treatise as a somewhat diffuse thema
for physiological investigation, I will add the following theses to it,
as they are intimately connected with it: —

1. By the activity of motor nerves there are excited not merely
combinations in the sensitive nerves, but the innervation of other
motor parts is diminished — for example, during the activity of the
flexors that of the extensors is lessened ; during the activity of the
respiratory muscles that of the inspiratory suffers ; so that, for
instance, the latter may even be paralysed by violent and long-
continued cough.

3. The vegetation of different organs, between which a combina-
tion of motor and sensitive-nervous activity exists, is intimately
connected. If there really be vegetative nervous filaments, they run
probably in company with the symmetrical nerves. Perhaps, how-
ever— indeed, it appears to me exceedingly probable — there is no
difference between the nature of the influence of the nerves of
motion and sensation on the one hand, arid that of those of vegeta-
tion on the other, except in modo.

2. The influence of the ganglionary system upon the vegetation
of those parts not supplied with ganglions, consists in the develop-
ment of the combined and reflex functions of the symmetrical
nerves. The office of the ganglions is to keep up the effects of
received impressions longer, and to maintain the combinations of
nervous activity in vibrations, as it were, until fresh vital stimuli
come into operation.

4. There are no cotemporaneous motions without intervening
sensitive combinations.

5. There are no cotemporaneous sensations without intervening
reflex motions.

VEGETABLE PHYSIOLOGY.

The appearance of five new treatises,* within little more than
twelve months, bearing on the study of Vegetable Physiology,besides
a new and much improved edition of a former work, is an indication
that the subject is now exciting a much more general attention than
has hitherto been paid to it. Botanists have too frequently over-
looked, in their eager pursuit of the systematic part of the science
the investigation of the structure and functions of the organs whose
external form and arrangement afford them the means of classifica'-
tion. The study of the affinities of plants, however, upon which
the Natural System is founded, requires an intimate acquaintance,
not only with organography, or the internal as well as external con-
formation of their parts, but also with morphology, the department
which treats of the laws regulating the arrangement and variation
of organs, and which occupies in botany a station corresponding to
that of philosophical anatomy in the study of the animal kingdom.
The investigation of the elementary structure of organs naturally
leads to the consideration of their functions ; and hence arises the
study of vegetable physiology, to prosecute which with success
requires a correct and extensive knowledge of the two former
departments, as well as some acquaintance with systematic botany.

Each of the treatises before us, with the exception of the last, is
well fitted to impart much correct information on these subjects,
which cannot but be interesting to the animal physiologist who

*1. An Introduction to Botany. By John Lindley, ph.d.. f.r.s., l.s., and g.s..
Professor of Botany in the University of London, and in the Royal Institution
of Great Britain. Second Edition. — London, 1835. 8vo. pp. 580.

2. Library of useful Knowledge. Botany. — London, 1835. 8vo. pp. 127.

3. The Principles of Descriptive and Physiological Botany. By the Rev.
J. S. Henslow, M.A., F.L.S., &c., Profcssor of Botany in the University of
Cambridge. — London, 1835. 12mo. pp. 322.

4. Introduction a I'Etude de la Botanique. ou Traite Elementaire de cette
Science ; contenant I'Organographie, la Physiologic, Methodologie, la Geographic
des Plantes, un aper^u des Fossiles Vegetaux, de la Botanique Medicale, et de
I'Histoire de la Botanique. Par M. Alph. De Candolle, Professeur a I'Acade-
mie de Geneve. — Paris, 1835. Tomes II. 8vo. pp. 1030.

5. Physiologic der Gevpasche. Von Ludolph Christian Treviranus, der
Phil, und Med. Dr. und ord. Prof, an der Univ. zu Bonn, &c. Erster Band. —
Bonn, 1835. 8vo. pp. 570.

6. Nouveau Systeme de Physiologic Vegetale et de Botanique, fonde sur les
Methodes d'Observation, qui ont ete developpees dans le Nouveau Systeme de
Chimie Organique ; accompagne d'un Atlas de 60 Planches d'Analysis. Par
F. V. Raspail— Paris, 1837.° Tomes II. Bvo. pp. 1257.

140 VEGETABLE PHYSIOLOGY.

takes an extended view of his science. The Introduction to Botany
by Dr. Lindley, is certainly the most valuable work of the kind in
our language, incorporating a great amount of original observations
with a judicious selection of the facts and opinions brought forwards
by other authors. The department of Organography is very fully
and ably treated of ; but the division appropriated to Physiology
appears to have been somewhat curtailed, many subjects of a highly
interesting nature being left untouched. A considerable portion
of the book is occupied with the explanation of terms used in sys-
tematic botany, and with rules for describing and naming plants,
which we should like to see transferred to a separate volume, and
their place in the present one occupied by an extension of the por-
tion devoted to physiology, the arrangement of which, as it stands
at present, we think capable of much improvement. Itisscarcely pos-
sible however to praise too highly the mode in which the greatest part
of the work is executed : the thorough acquaintance with his subject
manifested by the author, and the facility with which he communi-
cates his knowledge to others, render his explanations, even of the
more abstruse points, easy to be comprehended ; whilst the clearness
and candour with which he displays the arguments on both sides
of a disputed question incline us to accord, in almost all instances
with his opinion. The treatise on Botany in the Library of useful
Knowledge, by the same author, is an excellent outline of vegetable
anatomy and physiology, and we can strongly recommend it to such
of our readers as are commencing the study of these sciences.

The work of Professor Henslow, being written for a popular
series, is more adapted to the general than to the medical reader.
It contains an extremely clear outline of many departments of the
science, and forms an excellent introduction to the study of botany ;
but it is deficient in those higher and more general views which
are so interesting to the advanced student. It cannot be doubted,
from the author's high reputation as a botanist, that he could have
introduced more of novelty in his illustrations ; but any deficiency
in this respect is counterbalanced by the lucid manner in which
he has stated his views on several disputed questions of great interest,
some of which we shall hereafter notice more particularly.

The Introduction of M. Alphonse De Candolle is principally an
abridgement of his father's " Organographie" and "Physiologie
Vegetale," brought down to the date of its publication by the addi-
tion of new discoveries : it embraces a much more extensive range
of subjects than either of the works already mentioned ; and many
parts of it may be read with great advantage by those who are
already acquainted with them. Its first volume is devoted to ana-
tomy and physiology, with the theory of classification ; the second
contains the characters of the natural families, with an excellent out-
line of botanical geography and of fossil botany, and a short but
interesting history of botany.

The Treatise on Vegetable Physiology, by L. C. Treviranus, is
the most comprehensive and elaborate, on this particular department

VEGETABLE PHYSIOLOGY. 14t

of any of the works before us. It contains not only his own opin-
ions and researches, most of which have been already published in
the Zeitschrift fiir Physiologie ; but also a very complete abstract
of the views of all eminent writers on each disputed point ; and it
will consequently be of great value to those who wish to enter fully
into the investigation of the more obscure and intricate departments
of vegetable physiology. We are glad to see so large a portion
of the work devoted to the consideration of the Cryptogamia, which
have been comparatively neglected by most English and French
writers on Physiology. There are many valuable observations
scattered through the works of those who have devoted themselves
to the classification of this interesting division of the vegetable
kingdom, which have not yet been properly incorporated ; and, in
proof of the degree in which investigations into the structure and
functions of the Cellulares may assist us in the decision of several
doubtful points in the physiology of vascular'plants, we may refer to
the beautiful discoveries made by Mirbel in his researches into the
structure and mode of growth of the Marchantia Polymorpha.*

The volume of the Physiologie der Gewachse which has already
appeared embraces only the functions of Nutrition ; and, if those of
Reproduction are treated of in the same elaborate manner, the work
will be a valuable addition to those already existing. We certainly
differ from the author in many of the opinions which he expresses;
but the authorities on both sides are very fairly quoted, and much
research is displayed in the abundance of references, which are
of great value to the advanced student.

All the works which we have hitherto noticed profess to give an
outline, more or less completely filled up, of the present state of the
science of which they treat. That of M. Raspail has a far different
aim ; the object of the author being to demonstrate the fallacy of the
usually received doctrines of vegetable anatomy and physiology as
well as of classification, and to prove that every observation hitherto
made, which does not correspond with his own theories, has been fal-
sified either through ignorance or design. M. Raspail was previously
well known to us as possessing a remarkable degree of acuteness
and ingenuity as well as of originality of thought : his System of
Organic Chemistry contains many observations of great value, mixed
however with much that is erroneous, and which we hope to see
retracted by the author in the forthcoming edition of his work.
We applied ourselves to the perusal of the present volumes, there-
fore, with considerable expectations of the novelty and ingenuity
of their contents ; and in this respect we have certainly not been
disappointed, since it appears to be the plan of the author to deny
every fact, and to controvert every opinion, which is maintained by
authors of established reputation, especially if they happen to belong
to the Academy, his attacks on which are marked with a degree
of acrimony and violence totally unworthy of the character of a

* Nouv. Annales du Museum, torn. ii.
14*

142 YEGETABLE PHYSIOLOGY.

man of science. In his eager pursuit of analogies and generaliza-
tions, the author has, we think, frequently allowed himself to be led
astray from facts ; and he has evidently, in many cases, resorted to
observation with the view rather of confirming his preconceived
theories, than of employing them as the basis on which alone they
should be constructed. In this mode of philosophising, he reminds
us of the savant mentioned by Condillac, who thought that he had
discovered a principle which was adequate to explain, all the pheno-
mena of chemistry ; but, when he communicated his discovery to
a skilful chemist, he was informed that the facts were unfortu-
nately the reverse of what he had supposed. " Tell me what they
are," was the philosophers reply, " that 1 may explain them by my
theory." The real or affected ignorance of the investigations of
others, which is displayed by M. Raspail, is quite on a par with
the supreme importance which he attaches to his own. Thus, in
denying the existence of apertures in the Stomata (which he regards
simply as a modification of glands), he takes no notice of the beau-
tiful dissections of Ad. Brongniarl, or of the remarkably compli-
cated form in which Mirbel has shown that these organs exist in
the Marchantia. Of neither could he be really ignorant, and his
neglect of them appears to us to be readily explicable by the fact
that his theory requires that the cuticle should be destitute of
perforations.

Our criticism may appear harsh, but we can assure our readers
that it is deserved. We are sorry to see that a man of M. Raspail's
unquestioned ingenuity should be so far carried away by his zeal
for novelty as to neglect that patient inquiry, as well as that freedom
from prejudice, which are essential for the establishment of truth ;
and we do not consider it surprising that no one will give that
implicit credit to his observations which he somewhat imperatively
demands, but which is due only to men of higher reputation for
accuracy. Were we to review all the passages which we have
marked for special notice, our article would probably extend beyond
the compass of M. Raspail's volumes ; and we must therefore refer
our readers to the work itself, in which they will find much to amuse
as well as to interest, reserving a few of the fundamental propositions,
however, for future consideration. The only quotation which we
shall make is one which will afford a fair idea of the style and spirit
which pervade the work ; and we shall, contrar)^ to our wont, give
it in the original, as it would lose much of its point by translation.

"Larigueur mathemaliquejaveclaquelle s'eiichainentles theoremes
de la demonstration de la deuxieme partie, doit rappeler a la critique
qu'elle ne doit rien ecrire sans avoir medite,au moins quelques jours :
nous avons medite, nous, pendant douze ann6es, et les jours de la
plupart de ces annees ont eu plus de vingt-quatre heures pour nous."

We should be glad to see the science of physiology based upon a
more extensive generalization of the phenomena of vitality than has
usually been thought necessary. The study of comparative anatomy
is now recognized as the surest means of arriving at accurate results
on many disputed questions ; since the different forms of animals

VEGETABLE PHYSIOLOGY. 143

may be regarded, to use the language of Cuvier, as " so many kinds
of experiments ready prepared by Nature, who adds to or deducts
from each of them different parts, just as we might wish to do in
our laboratories, showing us herself at the same time their various
results." Vegetables present us with a greater simplification of the
vital functions than is afforded by the lowest animal ; since all the
changes necessary to the support of the individual and the continuance
of the species, are performed without the influence or interference of
those powers which are possessed, in a greater or less degree, by the
whole animal kingdom. Hence, the physiologist may advantageously
resort to the study of vegetable life for the explanation of many of the
proximate causes of those phenomena which are complicated in the
higher forms of organised beings by so great a variety of secondary
influences. In many cases, too, he has the means of investigating in
plants the changes produced by various agents on their structure
and functions, with much greater facility than when studying the
processes of the animal economy ; and he has the power of more
clearly distinguishing the effects of different vital stimuli.

The science of general physiology has, we regret to say, received
little attention in this country, and we cannot point to any original
work in our own language which professes to treat of it. The
translation of the elaborate Comparative Physiology of Tiedemann
has in part filled up the void ; but this treatise is less fitted to im-
press on the mind of the student comprehensive views of the subjects
which it discusses, than to present to those by whom they have
already been acquired a store of facts which may be used in confir-
mation or illustration of them. In the hope of in some degree sup-
plying to our readers the deficiency which we have ourselves felt,
and with the desire of inducing a portion of them to follow up a
course of investigation alike interesting and profitable, we shall
devote the remainder of the present article to an outline of those
departments of the structure and functions of vegetables, the know-
ledge of which is most important to the animal physiologist.

On the subject of the distinction between the two great kingdoms
of organized nature, we fully partake of the opinion expressed by
Professor Henslow, that structure presents us with no diagnostic
mark by which we can separate the lower and most approximated
groups of both from each other. " Perhaps," he remarks, " until
the contrary shall have been proved, we may consider the addition
oi sensibility to the living principle as the characteristic property
of animals ; a quality by which the individual is rendered conscious
of its existence or of its wants, and by which it is induced to satisfy
those wants by some act of volition."

The power of locomotion has usually been regarded as the distinc-
tion between certain groups of aquatic animals and vegetables ; and
the difficulty of ascertaining whether such motions are voluntary or
caused by accidental circumstances, has led some of the German
naturalists to describe beings as plants at one period of theirexistence,
and animals at another. We cannot doubt that there is a definite

144 VEGETABLE PHYSIOLOGY.

boundary to each kingdom, although the imperfection of our means
of observation will not always enable us to perceive it.

The primary tissues of vegetables offer an interesting object of
study to the general anatomist; and the difference of opinion which
still exists among botanists as to the precise nature of some of them,
and their mode of formation, shows that there is still much room
for investigation. Indeed, an examination into their nature demands
not only considerable manual skill and dexterity in the use of the
microscope, but what is even more important, a perfect readiness
to give up preconceived notions when they are inconsistent with
observation, and a determination to consider nothing as proved until
every mode of investigation has been employed^with the same result.
Every one who has examined doubtful objects hy a high magnifying
power, must be aware how much is often left to the imagination of
the observer ; and it is not difficult to account for the great discre-
pancy which exists in the statements of animal as well as vegetable
anatomists, all of whom, we have no doubt, conscientiously believed
that they saw what they have described.

The views of Dr. Lindley on the subject of \k\e primary tissues
appear to us more definite and correct than those of any other
writer, and we may therefore refer our readers to the statements
contained in his Introduction to Botany, with which our own obser-
vations in general coincide. Those who feel an interest in general
anatomy may also peruse with great advantage Mr. Slack'sadmirable
paper on this subject,* which is accompanied with the best delin-
eation of the elementary structures with which we are acquainted.
From his researches, added to that of other observers, it appears
that all the varied forms of vegetable tissue may be regarded as
taking their origin from the simple cell : and this fact has an inter-
esting connexion with the view now generally taken of the animal
tissues, according to which they may be all reduced to the cellular,
muscular, and nervous ; all the parts which minister to organic life
being essentially composed of the first of these and its numerous
modifications. The different forms of vegetable tissue are usually
classed under three general divisions, the cellular, ivoody, and
vascular. The first of these is composed of adherent vesicles, more
or less regular in form, usually containing fluid, and sometimeshaving
a spiral fibre generated in their interior. Woody tissue may be
regarded as a very simple modification of the cellular, the vesicles
being much elongated, and their sides possessing greater tenuity,
combined with greater strength. The transitions from the one form
to the other are almost imperceptible. Vascular tissue also con-
sists of elongated cells, but these possess a spiral fibre in their inte-
rior, which appears destined to prevent the obliteration of the canal
by pressure, when only filled with air ; and in this respect it bears
a remarkable analogy with the corresponding structure in the tracheae
of insects. We regard it as fully proved that the perfect spiral
vessels are in some way connected with the respiratory system, being

• Transactions of the Society of Arts, vol. xlix.

VEGETABLE PHYSIOLOGY. 145

always found to contain air ; but the various forms of ducts, pro-
duced by the partial rupture of the fibre, undoubtedly minister to
the conveyance of fluid. It is probable that fluid may also be con-
veyed by intercellular passages ; but we can by no means agree
with M. De Candolle in the importance which he attaches to these
canals in the economy of the plant, unless we are to regard the vital
circulation of Schultz as taking place in them. We agree rather
with Dr. Lindley in considering the doited ducts as the principal
means for the passage of the sap along the stem in most vegetables ;
and we generally accord with him, also, in respect to the cellular
origin of these canals, though we think that some of Mr. Slack's
observations render it probable that they may be occasionally modi-
fications of spirally formed ducts.

With regard to the mode in which the vesicles of the different
tissues are generated, little is certainly known. M. Raspail is of
opinion that the membrane forming the inner lining of every
vesicle is itself composed of other cellules in a rudimentary state,
and that, when these are stimulated to development by a process
analogous. to that of impregnation, (the contact of male and female
cellules,) new vesicles are formed within the old one, except when
vessels are produced which are developed externally. Starting
from this position, he gives a very plausible explanation of the
formation of the trunk, leaves, flowers, and, in short, all the organs
of the plant, each of which he regards as reducible to the type of a
simple cell capable of generating others in its interior; and any
cell possessed of this power is therefore supposed capable of producing
any organ, if placed in circumstances fitting for its development.
(§ 485.) We by no means wish to deny in toto the statements of
M. Raspail ; but we are confident that he is not arguing upon a
sure foundation when he maintains that every new vesicle of
cellular tissue is developed from the interior of a parent cell, like
ovules in an ovary ; since all the observations which have been
made on the early development of the Cryptogamia concur in this,
that new vesicles are added to the extremity of old ones, as any
one may distinctly see in the Chara, and as Mirble has demon-
strated in his admirable memoir on the Marchantia. ' According
to M. Raspail, every generating cell is composed of an external
colourless envelope, and a second layer, composed of green globules,
arranged in spirals which are the rudiments of the undeveloped
cells. When the parent cell forms an entiie organ by the develop-
ment of these cells, and of their off'spring, it is the external mem-
brane which forms the general cuticle. M. Raspail has evidently
generalized hastily on this subject from a few observations, and we
cannot regard his doctrines as capable of universal application,
although they may have some foundation in truth.

It is in the individual cells that the curious circulation of fluid
takes place which was described a century ago by Corti, and to
which the attention of botanists has been more recently directed
by Amici. This phenomenon is best observed in the very elongated

146 VEGETABLE PHYSIOLOGY.

cells of Chara and Nitella, but it has also been witnessed in the
transparent parts, especially the hairs, of many vascular plants, both
terrestrial and aquatic ; and it may be considered as probably ex-
isting in all cells at some period of their growth, being apparently
connected with the functions of nutrition. It has therefore no
analogy with the general circulation of animals ; but we may derive
an inference from it with regard to the possibility of the motion of
fluid without any evident organ of impulsion.

It would not be difficult to show that many of the laws of organic
development which have been suggested by the study of animal
structures, derive additional confirmation from their application to
the vegetable kingdom. The botanist can point to the endless
varieties of appearance and function assumed by the leaf as a striking
illustration of the doctrine of unity of type; and the reduction of
all the parts of the flower to the same elementary form by the
rigorous application of the laws of morphology, affords a beautiful
example of the principles of analogy. The higher forms of vege-
tables, like those of animals, pass, during their development, through
a series of stages in which the structure of each organ bears con-
siderable analogy with that which is permanent in some inferior
beings. Thus, the embryonic vesicle, which is the rudiment of a
vascular plant, apparently differs little in structure from the simple
cell which constitutes the lowest form of cryptogamic vegetation ;
but the latter, as soon as it is formed, is capable of maintaining an
independent existence, and of reproducing its species; whilst the
former derives from nutriment previously assimilated by its parent
the materials for the commencement of its development in the
interior of the ovule, and cannot continue to grow by its own un-
assisted power until the rudiments of its complicated nutrient
apparatus have been evolved. This germinal vesicle is filled with
a whitish fluid, and is placed in the midst of the pulpy mass which
constitutes the bulk of the ovule before impregnation. It seems at
first to consist of nothing but mucus, but it gradually becomes firmer
in texture, and absorbs from the tissue around it, increasing in size
so as to fill up the whole or a large part of the ovule. Still, how-
ever, it possesses a supply of nutriment stored up in its own
cotyledons, or in the albumen, which may properly be compared to
the yolk-bag of the eggs of birds. This is its state at the period of
the maturity of the seed, and thus it remains until excited by ex-
ternal stimuli to germinate, in which process a large quantity of
carbonic acid is disengaged. Up to this time, it consists of cellular
tissue and its simple modifications; and, in structure, habits, and
mode of existence, may be regarded as bearing a strong analogy
with the lower cellular plants, especially the fungi, which, like it,
deteriorate the air by the formation of carbonic acid, and, like it,
also thrive best when well supplied with moisture and protected
from light. As soon, however, as the plumula has elevated itself
above the surface, and the cotyledons have acquired a green colour,
the young plant begins to form woody tissue, but its vascular

VEGETABLE PHYSIOLOGY. 147

system is still imperfect. In this stage of its growth it may be re-
garded as corresponding with the mosses or Hepaticse ; and the
presence of stomata on its cuticle would remind us of a similar
structure in the curious Marchantia polymorpha. In a short time
the true leaves are evolved, which repeat in a much more perfect
manner the functions previously performed by the cotyledons ; and
the plant, having now exhausted the store of nutriment provided
for it, is totally dependent upon itself for support. The stem now
becomes provided with a regular fibro-vascular system, and the plant
may be considered as having arrived at the level of the ferns: we
must wait for full maturity before the reproductive organs are
evolved, the appearance of which marks the highest type of vegetable
organization.

Having thus attempted to point out a few of the transitory
resemblances exhibited by the more highly organized plants to the
permanent states of the lower, it would be interesting, did our
space permit, to attempt to apply to the- vegetable kingdom Mr.
Macleay's ingenious principle, that in the lowest and most imperfect
groups are sketched out the forms which are afterwards to be
adopted in the higher divisions.* It would not be difficult to trace
in the ever-varying forms of the Protophyta the outlines of the
characters of the four remaining divisions of the vegetable kingdom ;
but on this subject we cannot at present dilate, and shall content
ourselves with quoting an observation of that distinguished crypto-
gamist, M. Agardh : "Inter inferiores formas superiores ssepe
efflorescunt, sed rudes, et veluti experimenta ; sic anticipationes
formse perfectioris in plantis inferioribus non raro obveniant ; ut
etiam in plantis superioribus regressus ad formam imperfectiorem."t

Amongst other general analogies between the animal and vegeta-
ble kingdoms, we must not overlook that of their chemical compo-
sition. Although carbon may be represented as the characteristic
element of plants, as nitrogen of animals, it is now well known that
the latter element occurs much more frequently in plants than was
formerly supposed ; and it is interesting to remark, that the vegeta-
ble principle into which it enters most largely isfungin, a substance
confined to one of the groups which approaches nearest to animals
in structure. We may also observe, that the mineral ingredients
assisting in the formation of the organs of support in the lower
animals are those which are usually found in plants. Thus, carbo-
nate of lime, which is most frequent in vegetables, is most universally
diffused through the hard parts of animals, constituting the whole
of the skeletons of the massive Polypifera, the Mollusca, and forming
a part of those of the Articulata and Vertebrata. In like manner,
silex, which is the consolodating ingredient in the reticulated
skeletons of the lower Porifera, the class of animals most allied to
plants, also occurs, though sparingly, among the Algae, and enters

t

Horae Entomologicse, p. 233.

Aphorismi Botanici, Part V. Lundae, 1819.

148 VEGETABLE PHYSIOLOGY.

very abundantly into the structure of the higher plants, especially
the Graminese. All the mineral deposits which we find in plants
have, like those in the lower animals, a distinctly crystalline
structure; and some of these substances are so insoluble as to be
capable of being artificially crystallised by ordinary means. M.
Becquerel, however, has succeeded in crystallizing silex and the
carbonate and oxolate of lime, by means of a long-continued and
feeble current of galvanic electricity; and still more striking results
of a like kind have been since obtained by Mr. Crosse,* which, we
doubt not, were original on his part, but which had been anticipated,
in great measure at least, by the experiments of the former gentle-
men. It is not, perhaps, unreasonable to suppose that it is by
similar means that the process is effected in plants, since a con-
siderable quantity of electricity must be generated by the rapid
evaporation of the water which holds these substances in solution.
It might be argued from analogy that the calcareous granules in the
organized skeletons of Vertebrata partake of the same crystalline
arrangement, when first deposited, but that their form is afterwards
altered by the constant absorption and renewal which takes place in
true osseous textures.

The last general analogy we shall notice is the tendency to a
spiral arrangement manifested in both kingdoms. All the higher
plants may be regarded as constructed upon this plan, which is
exhibited both in the attachment of the foliaceous appendages and
in the formation of the stem itself: in both cases it might escape
the notice of a superficial observer, but the universality of the fact
is pointed out by De Candolle.t and has been more recently demon-
strated by Braun, whose researches are detailed in the works at the
commencement of the present article. Many stems have a tendency
to twist on their own axes; and, when a lateral direction is given at
the same time, the helical mode of growth is produced, so common
in climbing plants. The stalk generally coils from right to left,
but some species, like the hop, turn in a contrary direction ; and in
both cases the plant languishes and dies, if its natural mode of
growth is interfered with. The complication of the forms of
animals prevents our recognizing a similar arrangement in their
higher groups ; but it is the prevailing type of formation through a
large portion of the Mollusca, and we believe that it has also been
shown to govern the addition of new plates in the external skeleton
of the Echinoderma. In the Mollusca, the usual direction of the
spire is from right to left, but many genera invariably turn in the
contrary way, and their shells are then said to be reversed. In
some species the reversion is occasional, and it is not unfrequently
met with in bivalve as well as spiral shells. There can be little
doubt that, whatever cause produces the reversion of shells algo
efiects the transposition of organs in the higher animals; and it

* Report of the Meeting of the British Association, August, 1836.
I Organographie Vegetale, torn. i. p. 155.

VEGETABLE PHYSIOLOGY. I49

would not seem improbable that the abnormal formation is in some
way connected with the position of the embryo during its develop-
ment, since we constantly find it existing on one side of double-
bodied foetuses.

Although, however, we regard the" spiral mode of development
as that which predominates in the vegetable kingdom, we can by
no means assent to the speculations of M. Raspail, whose spiro-
vesicular theory appears to us one of the most ingenious absurdities
which we have ever encountered. The importance, however,
which he attaches to this favourite hypothesis requires that we should
not thus summarily dismiss it, and we shall therefore allow our
readers to judge of it for themselves, stating it as nearly in his own
words as the nature of an abridgment will allow. "The solution of
the problem I am about to enunciate,^' he says, "will account for
the whole system of vegetation ; and with the three elements of
each vesicle we shall have the means of organizing, according to
positive formulae, every plant already known or hereafter to be
discovered." (§ 715.) The following is the problem thus pomp-
ously introduced : — "The generating cellule being given, with its
three essential elements, to find in one of these elements the imme-
diate cause of the disposition and symmetry of organs in every
species of plant," (§ 716;) and it is thus solved. The globules, of
which he regards the parietes of the vesicle as formed, and which
are the rudiments of future organs, will not become developed until
they receive a certain stimulating or fertilizing influence, which is
conveyed to them by the spiral fibres winding round the interior
of the cell. This influence cannot be conveyed to them by a single
fibre, however, (and the existence even of this in every cell, be it
observed, is a pure assumption;) two spires, a .male and female,
revolving in opposite directions, are required for this purpose, and
it is only at their points of intersection that the rudimental globules
become developed; an effect which cannot be produced by any
number of spires revolving in the same direction. If the original
cell, therefore, becomes a trunk, and the secondary vesicles are
leaves or buds, the latter will be arranged on the first in a manner
corresponding with the crossing of the spires; and, where these are
equal in number, and revolve with the same rapidity in each
direction, the mode of disposition will be alternate. To produce
the opposite, spiral, or verticillate arrangement, we are required
to suppose a variation in the number of the spires or in their
relative velocity of revolution, by which their points of intersection,
and consequently the organs formed by the development of the
globules, may be brought to assume almost any position with regard
to each other, as is demonstrated by M. Raspail in a succession of
theorems.

In conceding to this theory the merit of great ingenuity, we con-
ceive that we give it all the credit which it deserves ; as an expla-
nation of the principles of vegetable structure, we reject it for many
reasons, of which the two following are the principal : — 1. The
m 15

150 VEGETABLE PHYSIOLOGY.

theory is not supported by any observations, except a single one
upon a Conferva, in which we are inclined to think that the fertility
of the author's imagination supplied the place of perfection in his
instrument ; and it is inconsistent with the statements of those who
have observed with the clearest and most powerful microscopes, as
well as with unbiassed minds ; all of whom agree in stating that the
spiral fibre, where it exists, is usually single, and that, when two or
more spires occur, they run in the same direction. 2. It assumes
that the arrangement of organs is constant in each species, and it is
therefore inconsistent with the well-known fact that in many plants
the position of the leaves is constantly varying ; those which are
usually opposite or alternate becoming verticillale, and vice versa.
We say nothing of the hypothesis of male and femal spires, and of
the impregnation of the subjacent globules by their contact, the
probability of which we may leave to the judgment of our readers ;
and we shall detain them no longer upon a question of so little prac-
tical utility, proceeding rather to the more strictly physiological
department of our subject.

. The existence and preservation of all organized beings is so inti-
mately connected with the changes which are constantly taking place
in their composition, that our simplest ideas of vitality are derived
from the observation of these processes, the organs by which they
are performed, and the concurrent circumstances on which they
are dependent. In all living beings, whether animal or vegetable,
the appropriation of matter from without, its conversion into a nu-
tritious fluid whose elements supply materials for the growth and
reconstruction of the fabric, and the excretion of the particles unfit
for these purposes, constitute the sum of the vital acts by which
the existence of the individual is maintained, and if we make due
allowance for the differences occasioned by the possession of the
faculties of sensation and voluntary motion, we shall find, on a close
examination, that there is really a much greater resemblance in the
mode by which the processes of nutrition are performed in both
kingdoms, than a superficial view would lead us to suppose.

Thus with regard to the ingestion of aliment, it has been frequently
maintained as a typical difference between vegetables and animals,
that the former absorb their nutriment from the whole or from spe-
cial parts of their external surface, whilst the latter receive it into
internal cavities where it undergoes a certain degree of preparation,
before absorption can be properly said to commence. "The spon-
taneous motion essential to animals," says Cuvier, " requires peculiar
modifications even in such of their organs as are essentially vegeta-
tive. Unprovided with roots to penetrate the soil, and constantly
to absorb nutrition, it was necessary that they should be able to
place within themselves a supply of aliment, and to carry its reservoir
along with them. Hence is derived the first character of animals ;
their intestinal cavity, from which passing through the pores and
vessels (which may be considered a kind of internal roots) the nu-
tritive fluid penetrates every part of their system, and sustains the

VEGETABLE PHYSIOLOGY.

151

whole." This view, though generally correct, requires to be greatly-
modified when we come to apply it to particular cases ; for not only
are there animals in which the most minute investigation has failed
to detect an approach to an internal cavity, but late researches into
the character of particular organs with which some plants are fur-
nished, render it very doubtful whether any definition of a stomach '
could be framed, in which they would not be included.

In the lowest tribes of cellular plants, which present no approach
to a vascular structure, absorption seems to take place by the whole
surface in nearly an equal degree ; and there is no transmission of
fluid from one part to another, each portion of the tissue imbibing
from the surrounding medium the nutriment which it requires. It
was in this manner that the greater part of the infusorial animalcules
were formerly supposed to derive their support ; but the researches
of Muller, Ehrenberg, and others, have established that their com-
plicated digestive apparatus entitles them to a place in the animal
scale far above that which has been usually assigned to them. The
gemmules of the porifera are however certainly nourished by external
absorption merely ; Dr. Grant states that " as long as they retain
this form, and for some time after their development in a fixed con-
dition, they present no perceptible canals or cavities of any kind in
their body ; nor do the polypiferous animals while they continue in
the same free state of ciliated movinggemmules. As thedevelopment
of the porifera proceeds, minute openings are observed to form on
the surface, which extend gradually through the body, producing
internal canals which terminate superfically in vents or fecal orifi-
ces."* These internal canals are bounded only by a fnore condensed
portion of the general cellular substance of the body, and may be
considered as a simple extension of the external surface. They are
incessantly traversed by currents of water which are drawn in by
the minute pores, and expelled by the fecal orifices, and there are
no distant cseca or stomachs for receiving and retaining the aliment
thus conveyed into the body : every part of its texture appearing
to be nourished by direct imbibition from the fluid in its neighbour-
hood. In this very simple organization we cannot help tracing a
strong analogy with the mode of nutrition in cellular plants. We
have noticed that in the lowest orders of these, the absorption is
nearly uniform through the whole surface ; but as soon as any
specialization of this function takes place, as we may partially notice
in the lichens, and still more in the fungi, (whose reproductive
system is completely separated from the nutrient,) it is manifested
in the development of filamentous processes of which the whole
length seems concerned in the active imbibition of fluid. Hence
the chief difference between the porifera and cellular plants in their
mode of receiving nutriment, is that in the latter, the extension of
the absorbing surface takes place externally ; whilst the alimentary
canals of the former may be compared to the ramified roots of a

* Grant's Outlines of Comparative Anatomy, p. 311.

152 VEGETABLE PHYSIOLOGY.

plant turned inwards ; a difference analogous to that of the bronchial
and pulmonary organs of aquatic and air-breathing animals.

Passing on to the vascular plants, we find each elementary fibre of
their roots to consist of a bundle of fibro-vascular tissue covered by
a lax cellular integument, and terminating in a blunt succulent point,
which has the power of absorbing fluid with great rapidity. The
spongiole, as this point has been termed, is sometimes spoken of as
a distinct organ ; but it is nothing more than the growing point of the
root, which with a few exceptions, lengthens only by additions to its
extremity. The soft lax tissue of the newly formed part causes it to
possess in an eminent degree the power of absorption ; but asthe fibre
continues to grow, and additional tissue is formed at the extremity,
that which was formerly the spongiole becomes consolidated into the
general structure of the root, and loses almost entirely its peculiar pro-
perties. The vessels contained in the elementary filaments are por-
tions of the general vascular system of the root which is in direct con-
nexion with that of the stem, serving to convey the absorbed fluid to
the organs where it is to undergo its elaboration. The most distinct
analogy to this structure in the animal kingdom is perhaps to be found
in the higher forms of the echinoderma, such as the holothuria, where
the alimentary matter is absorbed from the parietes of the internal cavity
by vessels corresponding to the mesenteric veins, by which it is con-
veyed "to the respiratory organs. The roots of plants have been
considered by some authors as analogous to the lacteal system of
animals ; but the erroneous nature of this comparison is evident
when we reflect that scarcely any rudiments of this system are found
in the invertebrata, and that in those classes whose organs of circu-,
lation are most nearly allied to those of vegetables, absorption is
performed by the general vascular apparatus.

It is obvious, from these particulars, that the alimentary system
of the lower forms of animals and vegetables differs extremely little ;
for in both is fluid absorbed by the general surface, or by a continu-
ation of it specially modified for the purpose ; in both are the nu-
trient materials brought into close contact with the parts they are
to supply, without an intermediate system of vessels ; and in both
also the function appears to be continuously performed without the
interference of volition. In the higher classes of both kingdoms
the apparatus assumes a more perfect and distinct form ; but even
in them we see in the power of superficial absorption, which is pro-
bably possessed in some degree by all, manifest traces of the primi-
tive community of function which characterizes the general surface
of the lower orders. This is manifested in vegetables by the im-
portant share which the leaves take in their nutrition ; for not only
is it through these organs that the greatest part of the carbon is de-
rived which enters into the composition of the tissues of the plant,
but they also appear capable of supplying, to a certain extent, any
deficiency which may occur in the quantity of moisture supplied by
the roots. It is an axiom in vegetable physiology laid down by
De Candolle, that " when a particular function cannot, according to

VEGETABLE PHYSIOLOGY. 153

a given system of structure, be sufficiently carried into effect by the
organ which is ordinarily destined to it, it is performed, wholly or
in part, by another." Thus, it is obvious, that when the roots are
absent or imperfect, or are implanted into an arid or barren soil,
any plant which flourishes in such circumstances must derive its chief
support either from the leaves, as in the epiphytal orchideae and
the greatest number of aerial parasites, or from the general surface,
when it performs the functions of the leaves, as in the cacti : and
if we consider the manner in which plants faded by the intense
action of light and heat are refreshed by the natural or artificial
application of moisture, we cannot doubt that absorption takes place,
in these instances also, by the general surface as well as by the
roots.

In many plants we may observe concavities in various parts, fitted
for the reception of the moisture caught from rain, or condensed
from dew ; and the mode in which this is applied to the nutrition
of the plant is not always evident. Frequently the fluid thus col-
lected is conveyed to the roots, by which it penetrates to the interior
of the plant ; but in many cases it is preserved in receptacles which
are usually formed by a modification of the leaf, and which vary in
the completeness of their structure from the simple hollow formed
in the leaves of the tillsensiaor dipsacus, to the extraordinary pitchers
{ascidia) of the nepenthes or dischidia. The exact office performed
by the pitchers in the vegetable economy is perhaps not yet fully
established. In nepenthes and sarracenia there is some doubt how
much of the fluid is the produce of secretion, and what proportion is
derived from without. It has been stated that one of its purposes is
to attract and destroy insects, whose decomposition may be a source of
nutriment to the plant, but this is doubtful. Theobjectof the pitchers
of the dischidia rafflesiana is, however, much less equivocal, and their
structure far more complicated than in the preceding instances.
This curious plant grows by a long creeping stem which is bare of
leaves until nearly its summit ; and, in a dry tropical atmosphere,
the buds at the top would have great difficulty in obtaining moisture
through the stem, and a sufficient supply is therefore furnished them
by the pitchers, which store up the fluid collected from the occasional
rains. "The cavity of the bag," says Dr. Wallich,* "is narrow
and always contains a dense tuft of radicles which are produced from
the nearest part of the branch, or even from the stalk on which the
bag is suspended, and which enter through the inlet by one or two
common bundles. The bags generally contain a great quantitj' of
small and harmless black ants, most of which find a watery grave
in the turbid fluid which frequently half fills the cavity, and which
seems to be entirely derived from without." The earth has been
justly spoken of as the common stomach of plants, supplying them
with nutriment ready to be taken up by their absorbent system,
whilst animals may be said to carry their soil about with them ; in

* Plantse Asiaticee Rariores. Vol. IL, p. 35.
15*

154 VEGETABLE PHYSIOLOGY.

this curious plant, the failure of its regular means of support has
called forth the addition of an organ, which, like the stomach of
animals, serves as a receptacle for the supplies it may occasionally
obtain, and principally differs from it in not being filled by an act
of volition on the part of its possessor.

The absorbent system of vegetables seems to correspond remark-
ably with that of animals in the non-existence of any visible pores,
through which the passage of fluid could take place, A vegetable
anatomist would have concluded from the structure of the roots of
plants, that the absorbents of the intestinal canal do not commence
by open mouths; and the most recent investigations seem to confirm
this opinion by direct observation. It cannot be doubted, however,
that the pores of the spongioles must have a sensible diameter, by
which their power of absorption is limited. If the roots of a plant
be placed in coloured solutions, they take up only the most finely
divided particles ; and if placed in dilute saccharine or mucilaginous
solutions, the watery part of the fluid will find its way through the
spongioles and become available for the sustenance of the plant,
while the greater part of the thicker material will be left behind.
In like manner, when saline solutions of a certain strength are pre-
sented to the roots, the water only, with a small proportion of the
salt is taken up ; and the remaining part of the fluid is found to be
more strongly impregnated with the salts than before. Such experi-
ments, however, do not afford any evidence of that discriminating
power in the spongioles which is so remarkable in the lacteals of
animals, and would rather confirm the analogy which w^e have
supposed them to bear with the general circulating sj^stem of the
lower animals, the remains of the absorbing powers of which are
perceived in the faculty now generally conceded to the veins of the
vertebrata. It has, however, been recently demonstrated by Dr.
Daubeny, that plants have to a certain extent the power of selection
by th'eir roots, since of three individuals of distinct species which
were made the subject of experiment, no one appeared to have taken
up the smallest quantity of nitrate of strontian, with a solution of
Avhich they were freely watered. {See Lindley^s Introduction ,
pp. 208-9.)

Some interesting experiments by M. Payen* on the effect of a
minute quantity of tannin in solution upon the absorbent power of
the roots, seem to render it likely that the apparent rejection of
particular substances which Dr. Daubeny has proved to exist, may
depend upon some organic change produced by them in the delicate
tissue of the spongioles. It does not appear however that the selec-
ting power is employed to prevent matter from being introduced
into the tissue of the plant which is capable of exerting a deleterious
influence upon it ; for many substances are taken up by the roots
which speedily put a stop to vital action if an opportunity is not
afforded for their excretion. Further researches on this subject

* Annales des Sciences Naturelles. N. S. Botan. IlL pp. 5-20.

VEGETABLE PHYSIOLOGY. I55

are much required ; and we would suggest that they might be ad-
vantageously prosecuted in connexion with the investigation, (which
can hardly be considered as yet concluded,) to what extent the
function of the lacteals is confined to the absorption of chyle, and
how far soluble foreign matters are taken up by the veins.*

The nature of the substances from which animals and vegetables
respectively derive their sustenance has been held to constitute an
essential difference between them ; and, although some late writers
have attempted to invalidate it by asserting that vegetables require
organic matter for their support, and that some animals are nourished
by inorganic substances, we shall endeavour to show that the dis-
tinction is generally if not universally applicable.

" There are, perhaps, only two forms of matter," says Dr. Lindle}'',
" which can properly be called nutritive ; the one is carbon, the
other water. Soil in its natural state is filled with the remains of
organic bodies, which decompose, and become converted into
carbonic acid. In proportion to the abundance of these is soil
fertile. If we look to the effects of manures, we shall find that in
most cases, except when their object is to alter the soil mechanically,
or to act as stimulants, as is probably the case with sulphate of
iron, their energy is in proportion to their capability of forming
carbonic acid. Yeast, for instance, which is one of the mogt active
manures we have, is so from possessing, beyond all other substances,
the power of exciting fermentation, and thus of causing the formation
of carbonic acid among the vegetable matter which lies buried in
the soil."

It has been fully proved by the experiments of Payen, that those
soils which afford the most steady and equable supply of moisture
and carbonic acid are the most favorable to the growth of plants ;
and that it is often desirable to moderate the decomposition of rich
animal manures by the addition of charcoal, the too rapid disengage-
ment of carbonic acid having a tendency to gorge the plant. If
vegetables were really nourished by the direct assimilation of matter
previously organized, we should expect that substances which cor-
respond most nearly to the materials of these tissues, such as gum
or sugar in solution, would be most favourable to their growth,
which is not the case. We are not aware of any instances in which
the decomposition of organic matter taken up by the roots has been
proved to be performed within the plant ; on the contrary, it has
been shown that colouring particles are deposited unchanged in the
tissues, that the odour of essential oils imbibed by the spongioles is
diffused through the whole plant, and that vegetable poisons also
traverse the stem and produce their peculiar effects on the irritable
organs above, without, undergoing decomposition. In all cases,
therefore, in which it can be proved that organic matter is absorbed,
it can also be shown that it is of such a nature as not to contribute
to the nutrition of the plant. It has also been found that the ascend-

* Supplement to Alison's Physiology, p. 40.

156 VEGETABLE PHYSIOLOGY.

ing sap of all plants, when examined sufficiently low in the trunk
to avoid the fallacy occasioned by the dissolution of secretions pre-
viously deposited in its course, is very uniform in its composition ;
and this would hardly be the case if it were dependent upon a
constantly varying supply of organic matter in different stages of
decomposition, such as is afforded by different soils. The opinion
that carbonic acid and water form the essential food of plants, is
confirmed by the fact that many even of the more highly organized
species will grow in circumstances where no other kind of nutriment
is accessible to them ; and no one is ignorant that the simpler forms
of lichens will appear on barren rocks in the midst of the ocean,
increasing by absorption from the atmosphere alone, and preparing
hy their decomposition a nidus for the reception of the germs of
higher orders of vegetables. Of the various mineral substances
which are taken up in solution by the roots of plants, a proper
supply appears to be in many cases essential to the health of the
individual ; but as they undergo no assimilation or change of com-
position, and are simply deposited in the tissues, they can hardly
be considered as contributing directly to its nutrition.

Some naturalists have contended that all animals do not necessarily
derive their support from matter previously organized ; but, we
must confess that the instances which they have produced in favour
of this opinion are far from being satisfactory. It is true that the
spatangus fills its stomach with sand, but it derives its nutriment
from the minute animals contained in it ; the earthworm and some
kinds of beetles are known to swallow earth, but it is only to obtain
from it the remains of organized matter which are mixed with it ;
and, in fact, the inorganic matter thus taken into the stomachs of
these animals, no more contributes to their nutrition than the gravel
swallowed by graminivorous birds, or the chalk eaten by a hen
preparing to lay. We are therefore inclined to agree with those
who consider plants as intermediate in their constitution between
animals and inorganic matter. " The only final cause," says Dr.
Roget, "which we can assign for the series of phenomena constitut-
ing the nutritive functions of vegetables, is the formation of certain
organic products calculated to supply sustenance to a higher order
of beings. The animal kingdom is altogether dependent for its
support, and even existence, on the vegetable world. Plants appear
formed to bring together a certain number of elements derived from
the mineral kingdom, in order to subject them to the operations of
vital chemistry ; a power too subtle for human science to detect, or
for human art to imitate."

In our observations on the nutrition of plants, we have hitherto
referred to those only which are possessed of a complete system of
absorbing and assimilating organs ; grafts and parasitic plants form
a separate object of consideration. It is well known that it is essential
to the success of the process of grafting, that there should be a close
alliance in species between the two plants to be united ; and hence
it is inferred that the ascending sap varies in composition in different

VEGETABLE PHYSIOLOGY. I57

families. This may be partly true, since it is known that in rising
through the stem it dissolves a- portion of the peculiar secretions
stored up from the former year ; but so many concurrent circum-
stances influence the result of the operation, that it is difficult to
say how much is to be attributed to each. Thus, it is essential to
success that there should be an analogy between the modes of growth
in the stock and graft ; that the two individuals should be naturally
in sap at the same period ; and that the processes of vegetation should
be carried on in both with the same vigour.

The manner in which different species of parasitic plants derive
their nutriment, and the analogies which may be traced between
them and certain parts of the animal kingdom, would afford a very
interesting subject for investigation, a few points of which we shall
briefly indicate. "If we examine the influence of living vegetables
on one another," observes De Candolle, "we shall see them almost
always in a state of contention, less violent and apparent than that
of men or animals amongst themselves, but of long duration, and
very important in its results." This war is maintained by parasitic
plants which live, like carnivorous animals, at the expense of their
fellows ; though their injurious effect is not always incompatible
with the life of the individual upon which they prey.

It is important to draw an accurate distinction between true and
false parasites. The latter vegetate habitually on the surface of
other plants, without deriving from them any nutriment except a
small quantity of superficial moisture ; they will live almost indis-
criminately on different trees, or in any situations which will afford
them the means of attachment and a small supply of humidity ; and,
being furnished with their own organs of absorption from the atmo-
sphere, they send no roots into the interior of the plants on which
they live. They are therefore only hurtful by covering a portion
of the general surface of the tree, by partially shading it from the
light if their vegetation is very luxuriant, by affording a nidus to
injurious insects, and, in the case of many creeping plants, by acting
as ligatures round stems and branches whose diameter is on the
increase. Amongst these we may reckon the lichens and other
superficial parasites among the cellulares ; as well as the ivy and
many of the viteaceas, a large proportion of the tropical orchidese,
and, in general, all plants which have creeping scandent stems.

True parasites, on the other hand, are not furnished with perfect
roots of their own, and are therefore obliged to draw more or less
of their nourishment from the juices of other vegetables. They
may be divided into two great physiological classes ; the plants
belonging to the first possess leaves or other green parts exposed to
the influence of light, and have the power of elaborating for them-
selves the crude sap derived from the ascending current of the trees
on which they grow; the second class comprehends those which are
deficient in digesting as well as absorbing organs, and are therefore
compelled to derive their food from the juices of plants which have
already undergone some elaboration. Of the first class, which may

158 VEGETABLE PHYSIOLOGY.

be termed chlorophyllous parasites, a characteristic example is the
misletoe, which vegetates on almost all exogenous trees, implanting
itself on the bark and sending its radical fibres to the interior of
the stem, penetrating and uniting themselves firmly to the woody
fibre, with which they form so intimate a connexion that coloured
fluids will pass from the stock to this natural graft — for thus it may
in some respects be considered. It does not appear that any con-
nexion exists between the misletoe and the bark beneath it, which
indeed is always found to be in a state of sphacelation around its
insertion. All the parasitic plants of this class (principally belong-
ing to the order Loranthaceae,) appear to grow with nearly equal
facility on a great variety of trees, a fact which we might anticipate
from the great similarity which exists between the crude sap of
various kinds ; but it is remarkable that the misletoe is very rarely
seen to grow on the oak, and it is perhaps from this circumstance
that the occurrence was formerly regarded in a religious light.

The greater part of the second or Aphyllous class of parasites
grow upon the roots or underground stems of other plants, no part
of them appearing above the surface (in most cases at least,) except
the flower stalks which are occasionally sent up. Amongst this,
class are the orobanche or broom-rape, and the Lathrsea squamaria, -
whose curious structure has been minutely described by Mr. Bow-
man.* As they derive their nutriment from the previously elaborated
juices of other plants, by suckers fixed in the bark, they are, as we
might expect, more restricted as to the number of species upon which
they grow.

It appears to us that sufficient attention has not been paid to the
physiology of nutrition in forming a natural classification of the
vegetable kingdom. If it be true, that plants in general have the
power of deriving their nutrition from inorganic matter, and thus
of converting into organized products substances much lower in the
natural scale, we may conceive them to hold a corresponding rank
with herbivorous animals, which, by means of their complex digestive
apparatus, assimilate and convert into animal proximate principles,
matter previously much inferior in organization. True parasitic
plants, on the other hand, like the carnivora, derive from beings as
highly organized as themselves, those supplies of nutriment which
their simpler conformation requires to have been already partially
prepared by other means. The omnivorous animals, too, find a
parallel in some of those parasitic species which derive their nutri-
ment partly by suckers applied to other plants, and partly by means
of roots sent into the surrounding earth ; and the parasitic fungi,
like many of the lower kinds both of carnivorous and herbivorous
animals, derive their support only from dead or decaying organized
substances, and may not unaptly be termed, like insects, "the
scavengers of nature."

Plants, like animals, are infested by the growth of parasites within

* Linnaean Transactions, Vol. xvi.

VEGETABLE PHYSIOLOGY. I59

them ; and it is a question not yet decided whether the development
of these entophytes, which all belong to the fungi, is to be considered
as the result of a diseased action in the plant itself, or of the intro-
duction of the germs from without. It has been concluded by
Unger*, as the result of his observations on the changes produced
by them from their very commencement, as well as of a priori
argument, that the uredo, secidium, puccenia, &c. which constitute
the appearances known by the names of blight, mildew, smut, &c.,
are to be considered as the exanthemata of plants, being essentially
maladies des stomates ; and he thinks it questionable whether
such productions as the secale cornutum may not be owing to a
similar cause. He observes that these morbid growths are most
liable to occur in those portions of plants where vegetation is most
active, such as the green parts in general, and the leaves in particular ;
and he remarks that, on the surface of healthy bark, we generally
find either more perfect cryptogamia, or phanerogamous parasites.
The cellular parasites evidently flourish best when the bark is ap-
proaching decay ; and it often happens, that, whilst the stem and
principal branches of an old tree are covered by mosses and lichens,
these are seen to diminish and disappear as we advance towards the
younger and fresher portions. The presence of entophytes is said
by Unger to be connected with that of the stomata ; and he supposes
it to be from some obstruction to their functions that the exanthemata
arise. They generally appear at the season of most active vegeta-
tion, namely, the spring and early summer ; whilst the period for
the most abundant and rapid development of the true fungi is the
autumn and the commencement of winter. It is but fair to state,
however, that Mr. Berkeley, whose authority on such matters is
high, considers Unger's statements to be inconclusive.! In those
cases in which fungi most unequivocally present themselves, it may
be doubted whether they are not rather the consequence than the
cause of the disease ; for we know that the habit of the class is to
appear on matter in a state of incipient or of advanced decomposition ;
and it would not seem improbable, that like some of the parasites
which peculiarly infest the animal body when in a state of weak-
ness, the fungi meet with a nidus fitted for their development in
those parts of the vegetable tissue which are undergoing alterations
by disease. It is believed by M. De Candolle, that the germs of
the entophytic fungi are taken up by the roots and carried along
with the current of sap, being deposited and developed in the parts
where vegetation is most active ; and various facts may be adduced
in support of this opinion. We cannot at present dilate more upon
this very interesting subject : its close connexion with various
doubtful points in animal pathology need scarcely be indicated ;
and we would suggest it as an important question in general physi-
ology^ whether plants or animals of a high degree of organization

* Annales des Sciences Naturelles. N. S., vol. ii.
t Hooker's British Flora. Vol. IL Part II. p. 360.

160 VEGETABLE PHYSIOLOGY.

are capable of producing from various parts of their tissues, beings
corresponding to those of the inferior orders of their respective
kingdoms.*

Though there is no motion of fluids in plants exactly analogous
to the general circulation of the higher animals, an investigation
into the mode in which the sap absorbed by the roots is propagated
to the leaves without a manifest organ of impulsion, cannot but be
interesting to the animal physiologist ; since it affords him some
means of distinguishing the effects of the heart's action from those
of other causes which influence the motion of the blood. Philosophers
in all ages have attempted to explain the ascent of the sap in plants,
some attributing it to simple mechanical powers, some regarding
it as an immediate effect of vital agency ; and others, with more
probability, considering it as partly dependent upon each class of
causes. In watching the gradual specialization of the organs of
nutrition in the lower orders of cellular plants, we may observe
that, as soon as any tendency to vertical elevation is manifested, it
becomes necessary that some means should be provided for the
transmission of fluid in a determinate direction ; and this is ac-
complished by means of elongated cells, such as we find in the
stems of some fungi. The conveyance of fluid thus performed
would seem to differ little, except in its possessing a determinate
direction, from that which takes place in the cellular tissue of all
plants, its hygroscopic properties causing each cell to communicate
to its neighbours any superabundance of fluid which it may possess ;
and it is observable that when the fluid has traversed the elongated
cells and arrives at a part of the plant where the vesicles have a
rounded form, it is equally diffused throughout. The ascent of the
sap in vascular plants appears to take place partly through the
young wood being conve3'ed from one tubular fibre to another by
the hygroscopic, or, to use Dutrochet's expression, the endosmome-
tric properties of the tissue ; and partly through ducts specially
organized for the purpose. These are sometimes of considerable
diameter and uninterrupted by transverse partitions, especially in
plants having long slender stems, and whose active vegetation re-
quires a rapid transmission of fluid from the roots ; the bamboo
cane and the vine afford good examples of this structure. It be-
comes an interesting question to determine by what power fluid is
propelled through these vessels, the nature of their parietes for-
bidding us to suppose that any contraction on their part can be in-
strumental to the effect, and no evident organ of propulsion exist-
ing at their commencement. Our first object, therefore, is to
inquire into the causes which modify the quantity of fluid absorbed,
and the velocity of its transmission ; and it cannot be questioned
that the principal of these is the demand occasioned by the vital
processes performed in the leaves. Of the fluid conveyed to these
organs, the greater part is lost by transpiration, a function partly

* See Fletcher's Rudiments of Physiology. Part II. p. 13.

VEGETABLE PHYSIOLOGY. 161

dependent upon simple evaporation under the influence of heat and
a dry atmosphere, and partly upon exhalation from the stomata
under the stimulus of light. It has been ascertained by many ex-
periments that the quantity of fluid absorbed by the roots is in
strict relation with that transpired from the leaves; and that during
the night, and in winter, when the transpiration is wholly at a stand,
the process of absorption is almost entirely checked. Even in
winter, however, absorption may be artificially excited by any
circumstance which occasions a demand for fluid; thus, if a branch
of a vine growing in the open air be introduced into a hot-house,
its buds being called into action by the increased temperature im-
mediately attract fluid from beneath it, and thus the whole system
is put in motion; and De CandoUe has shown that in such a case
the fluid consumed by the young leaves is really attracted from the
cold earth, and not absorbed from the atmosphere of the hot-house.
The ascent of the sap in spring may be explained upon the same
principle, and we shall quote Dr. Lindley's account of it, which is
partly derived from that of Du Petit Thouars.

"In the spring, as soon as vegetation commences, the extremities
of the branches and the buds begin to swell : the instant this happens,
a certain quantity of sap is attracted out of the circumjacent tissue
for the supply of those buds; the tissue which is thus emptied of
its sap is filled instantly by that beneath or about it; this is in turn
replenished by the next; and thus the whole mass of fluid is set in
motion from the extremities of the branches down to the roots.
Du Petit Thouars is, therefore, of opinion, that the expansion of
the leaves is not the effect of the motion of the sap, but on the
contrary is the cause of it; and that the sap begins to move at the
extremities of the branches before it stirs at the roots. That this
is really the fact, is well known to foresters and all persons accus-
tomed to the felling or examination of timber in the spring; and to
gardeners who are occupied with forcing the branches of plants in
winter, while their trunks are exposed to the weather."

There is no need therefore of having recourse to the supposition
of accumulated irritability for the explanation of these pheno-
mena, which can be so readily accounted for on known principles ;
and it is obvious that the facts just quoted afford a strong confirma-
tion of the opinion now entertained by many eminent physiologists,
that the motion of the blood in the capillaries is very greatly
dependent on the changes which it undergoes in them. With
regard to the degree in which the motion of the sap is dependent
upon the propelling power of the spongioles, we feel much disposed
to agree with the views expressed by Professor Henslow :

"The water imbibed by the spongioles is also propelled forward
by them with considerable force, and the effects are strikingly
analogous to those exhibited by the endosmometer. These effects
manifestly bespeak an action very different from the ordinary
results of capillary, and indicate the presence of a powerful force, a
m 16

162 VEGETABLE PHYSIOLOGY.

'visd, tergo/ residing in the lowest extremities of the roots by
which the propulsion of the sap is regulated. Although these
results so closely resemble those of endosmose, there still exists a
difficulty in connecting the two phenomena ; for, whilst we may
admit the possibility of an interchange between the contents of the
vesicles composing the spongioles, and the water in the soil which
surrounds them, by the ordinary operation of endosmose, it is
difficult to explain how the sap may be propelled forward so violently
as it appears to be, in the open channels through the centre of the
stem, which contain crude sap of nearly the same specific gravity as
water itself. It would be further necessary to account for the
manner in which a continued supply of fresh materials is obtained
for carrying on the endosmose, which must otherwise soon cease
when the fluid within has become much diluted. We shall find,
however, that a constant supply of fresh material is actually provided
by the direct action of the vital force, during a subsequent period
in the function of nutrition ; and hence it is not impossible, though
it has not been proved, that both the propulsion as well as the
absorption of the sap may principally if not entirely be owing to
the operation of mechanical causes ; dependent, however, for their
lengthened continuance upon the existence of the vital energy by
which those conditions are perpetually renewed, and without which
the endosmose would of necessity soon cease." {Principles, p. 182.)

The sap in its progress upwards is known to acquire an admixture
of matter previously assimilated, either by coming in contact
with the descending current, or as Mr. Knight's experiments make
it appear, by dissolving secretions laid up in the wood. This adr
mixture may serve the purpose alluded to by Professor Henslow,
of increasing the specific gravity of the fluid, and thus maintaining
the activity of the process of endosmose; but it also appears to be
the first step in the assimilation of the crude materials of the sap.
*'This assimilation," says Dr. Alison,* "by means of a previously
existing product of vital action, is a general law of the maintenance
both of animals and plants."

The chemical changes which the sap undergoes in the leaves,
by exposure to the atmosphere, have been usually attributed to the
h^nci'ion o? respiratio}i; and as it is now beyond doubt that they
are of an opposite nature to those produced by the respiration of
animals, many naturalists, and amongst them Cuvier, have proposed
to establish upon this contrariety an essential distinction between
the two kingdoms. We shall presently show, however, that this
opinion may be reasonably doubted. With regard to the aggregate
effects produced on the atmosphere by the growth of plants, we
may quote from Dr. Lindley an account of Dr. Daubeny's recent
experiments, which give a result entirely opposed to those of Ellis.

' Professor Daubeny has ascertained by experiments partially

* Supplement, p. 5.

VEGETABLE PHYSIOLOGY. 163

communicated to the British Association, but not yet published, that
plants undoubtedly exercise a purifying influence on the atmosphere.
In a letter I have recently received from him, he expresses himself
thus ; ' As the observations of Ellis left it in some doubt whether
the balance was in favour of the purifying or the deteriorating influ-
ence upon the air, which is exercised by plants during different
portions of the day and night, I conducted my experiments in such
a manner that a plant might be inclosed in a jar for several successive
days and nights, whilst the quality of the air was examined at least
two orthree times a day,andfresh carbonic acid admitted as required.
A register being kept of the proportion of oxygen each time the
air was examined, as well as of the quantity of carbonic acid intro-
duced, it was invariably found that, so long as the plant continued
healthy, the oxygen went on increasing, the diminution by night
being more than counterbalanced by the gain during the day. This
continued until signs of unhealthiness appeared in the confined plant
when, of course, the oxygen began to decrease. In a perfectly
healthy and natural state it is probable that the purifying influence
of a plant is much greater ; for, when I introduced successively
different plants into the same air, at intervals of only a few hours,
the amount of oxygen was much more rapidly increased, in one
instance to more than forty per cent, of the whole instead of twenty,,
as in the air we breathe.''

It has been ascertained from other experiments that a small quan-
tity of carbonic acid is perpetually evolved by the leaves both
day and night ; and the consideration of these phenomena led Pro-
fessor Burnett to the opinion that, under the name of respiration,
two distinct phenomena are confounded. He observes* that the
production of carbonic acid is constant during the life of a plant,
that it takes place both by day and night, in sunshine and in shade ;
and that this process, which he considers strictly analogous to the
respiration of animals, is essential to its existence ; for, if deprived
of oxygen and confined in carbonic acid gas, vegetables quickly die.
On the other hand, the green parts of vegetables, at certain times
and under certain circumstances, decompose carbonic acid, and ren-
ovate the air by the restoration of its oxygen ; but this occasional
renovation may be referred not to the respiratory but to the diges-
tive system ; and so completely is the process dependent upon the
stimulus of sun-light, that plants made to grow in the dark, although
they increase in size, do not augment the absolute volume or weight
of their solid contents, and even lose some of their carbon by respir-
ation. Here again the analogy holds good between the functions
of respiration and digestion in plants and animals ; for to both is
carbonic acid deleterious when breathed ; and in both is it invigor-
ating to the digestive system when absorbed as food.

Plants when exposed to strong sun-light, will thrive in an atmo-

* Journal of the Royal Institution. New Series, Vol. I.

164 VEGETABLE PHYSIOLOGY.

sphere containing 7 or 8 per cent, of carbonic acid ; but when placed in
the shade they quickly die ; and this fact has an interesting connexion
with the luxuriance of the fossil flora of the coal formations, which
abounds in gigantic specimens of plants whose development is now
much inferior, even in tropical climates. It is theopinion of Adolphe
Brongniart, that the atmosphere of that epoch was highly charged
with carbonic acid, as well as with humidity ; and that these vegetables
by the assistance of powerful sun-light, drew from it that nutriment
which there was not sufficient soil to afford them, and, by thus puri-
fying the atmosphere, prepared the earth for the residence of the
higher classes of animals.

The chemical changes which are produced by the action of the
atmosphere upon the crude sap, probably take place in part through
the medium of the cuticle of the leaves and other green surfaces ;
but some are of opinion that a more direct contact is effected by the
entrance of the air through the stomates into the intercellular spaces.
Besides this, it is not improbable that the office of the true spiral
vessels which are situated in the interior of the stem, is in some
way connected with the function of respiration ; for the researches
of Bischoff have shown that the air contained in them consists of a
large proportion of oxygen, which probably discharges some impor-
tant duty in the economy of the plant ; and these vessels are brought
into relation with the atmosphere by their communication with the
leaves. Hence the Respiration of plants appears to bear a close
analogy with that of insects, an analogy which was long ago suggested
by the spiral structure of the trachea in each ; but it must be
acknowledged that further researches are wanting before we can
speak with confidence on the subject.

The animal physiologist will naturally be disposed to inquire
whether any development of heat takes place during the respiration
of plants ; and we might look in vain for any such manifestation
during the ordinary performance of the process. There are two
periods, however, during the life of a plant, in which respiration
goes on with remarkable activity, and in both a considerable degree
of heat is generated. In germination, the first of these periods, a
large quantity of the surrounding oxygen is converted into carbonic
acid, by the liberation of carbon from the seed ; and this appears to
be the effect of the conversion of fecula or its modifications into
sugar, a principal more fit for the support of the young plant. In
the second period, that of flowering, the changes which take place
are very similar to those produced by germination. A large quan-
tity of oxygen is converted into carbonic acid by the action of the
flower ; a considerable quantity of heat is developed ; and it is
believed that the fecula previously contained in the disk is changed
by this process into saccharine matter, adapted for the nutrition of
the pollen and young ovula ; the superfluous portion flowing off in
the form of honey. In studying the changes produced during the
flowering of plants, we find a direct relation between the carboniza-

VEGETABLE PHYSIOLOGY. 165

tion of the air and disengagement of caloric, and the development
of the glandular disk. This is especially remarkable in the arum
when a thermometer placed in the midst of a mass of inflorescence
has been seen to rise to 121°, while the temperature of the external
air was only 66°. From the experiments of Saussure, it appears that
the disengagement of heat and the disappearance of ox3^gen are prin-
cipally caused by the action of the organs of fecundation since ; when
the floral envelopes are removed, the quantity of oxygen consumed
by the remaining parts is much increased in proportion to their
volume. In one instance, the sexual apparatus of the arum italicum
consumed in twenty-four hours 132 times its bulkof oxygen. Unless
we admit the existence of a nervous system in vegetables, we can
hardly consider the development of heat during germination and
flowering in any other light than as a strictly chemical effect arising
from the combination of carbon and oxygen ; and a strong analogi-
cal argument might hence be drawn in favour of the theory which
attributes the development of animal, heat principally to the
chemical changes produced by respiration. It has been asked why
a disengagement of caloric does not take place in all flowers, if it
be produced in this manner ; but it should be remembered that in
by far the greater number the heat is carried off by the atmosphere
the instant that it is developed ; and that it is only where flowers
are collected in great numbers within cases which act as non-con-
ductors and confine the heat, as happens in arums, that the elevation
of temperature becomes appreciable. M. Raspail, however, offers
an explanation of the phenomenon, which differs considerably from
that which we have given. He supposes that the elevation of tem-
perature indicated by the thermometer is due, not to caloric liber-
ated from the flower itself, but to the concentration on the bulb of
the rays reflected from the interior of the spadix. He supports
his view by a series of observations which he made on the compara-
tive heights of two thermometers, of which one was placed in front of
a cone of silk, and the other exposed without any envelope ; and
he states that when influenced by the direct rays of the sun, the
former stood nearly 20° above the other. Although we are far
from asserting that no allowance is to be made for the source of
heat which he has pointed out, we do not regard his experiments
as conclusive in favour of its being the only one ; since he has neg-
lected the fact that in Hubert's experiments in the Isle of France
on the arum cordifolium, the greatest elevation of temperature was
always observed at a time when the rays of the sun are least power-
ful, namely at sunrise ; and also that in the experiments of Brong-
niart upon colocasia odora,the evolution of heat continued to increase
rapidly from the complete opening of the flowers to the period of
the emission of the pollen.

It appears that the removal of carbon by its combination with the
oxygen of the atmosphere is essential also to the ripening of fruit ;
for when placed in an atmosphere deprived of oxygen, this function

16*

166 VEGETABLE PHYSIOLOGY.

is suspended ; and if the fruit remains attached to the tree, it dries
up and dies. The extrication of carbon appears due, as in germina-
tion and flowering, to the conversion of gum and other proximate
principles into sugar.

If the hypothesis of Dr. Prout* with regard to the source of car-
bon in venous blood be correct, a beautiful analogy exists in the
effects of respiratation on the economy of animals and vegetables.
"Gelatin," he says, "which contains three or four per cent, less
of carbon than albumen contains, enters into the structure of every
part of the animal frame, and especially of the skin ;" and as
albumen exists largely in the blood, without any gelatin, he con-
siders that " the conversion of albuminous matter into gelatin is
one great source of the carbonic acid of venous blood." Now,
gum in the vegetable kingdom may be considered to hold a rank
very analogous to that of albumen in the animal system ; both
are immediately formed from the crude nutriment, and serve as the
pabulum of the tissues in general ; and both are more universally
diffused than any other principle. The conversion of albumen
into gelatin, therefore, would seem to be a process very similar to
the change of gum, and fecula, which is but a modification of it,
into sugar.

The fluid which has thus been elaborated in the leaves, partly by
the obvious processes of transpiration and respiration, partly by the
hidden agencies of vital chemistry, is carried from the leaves, by
the under stratum of veins, and appears to descend through the
general cellular system of the stem. In Endogens, therefore, it is
probably diffused equally through the whole trunk ; whilst in Exo-
gens it is principally conveyed downwards by the bark, and carried
into the interior by the medullary rays. The descending sap pro-
bably contains, ready formed, not only the nutritious secretions
destined for the increases of the tissues, but the greater part of those
special secretions whose uses to the individual plant the physiolo-
gist is at a loss to explain, although their importance in the general
economy of nature is so evident. Many of these are stored up in
particular receptacles, without our being able to detect any special
apparatus by which they are separated from the circulating fluid ;
but in some cases a distinct glandular structure is very apparent,
and the immediate secretions effected by it are collected in an isola-
ted form. The present state of our knowledge does not allow us
to state whether these are merely separated from the proper juice
or are the products of a new combination of its elements ; but it
should be recollected that many vegetable principles are so nearly
allied to each other in composition, though totally differing in exter-
nal qualities, as to be readily convertible into one another by ordi-
nary chemical processes ; and we need not, therefore, be surprised
to perceive such changes effected in plants without any very evident
apparatus for the purpose. It would seem not unlikely from recent

* Bridgewater Treatise, p. 524.

VEGETABLE PHYSIOLOGY. 167

investigations into the electrical state of different parts of plants,
that electricity has a more extensive influence in the transformation
of organic products in the living system than has generally been
supposed ; and these might be advantageously contrasted with the
observations of Donne on the electrical condition of different tissues
in the animal body. The recent more accurate analysis of what
have usually been termed the proximate principles of vegetables,
has shown that many of them are formed by the union of compound
electro-positive bases with oxygen, water, &c. ; and that the mode
of combination in organic and inorganic bodies is not so essentially
distinct as was formerly believed.* From the continuance of such
discoveries in organic chemistry, aided by well directed inquiries
in vegetable physiology, we might not unreasonably look for impor-
tant results.

The nutritious secretions, sugar, gum, fecula, and lignin, may
all be regarded as compounds of carbon and water, and differ very
little from one another in the proportions of their elements. Sugar,
from its crystaline form and simple constitution, is regarded by Dr.
Prout as occupying the intermediate place between organic and
inorganic compounds ; whilst gum, from the universality of its diffu-
sion through the vegetable kingdom, may be considered the essential
pabulum of the tissues of plants. Fecula has been shown by Raspail
and others to be nothing but a semi-organized form of gum, adapted
to be stored up for the nutrition of young parts, without beingliable
to be dissolved by the fluid circulating around it. With regard to
lignin or woody fibre, it must be considered as a still more highly
organized product ; and if it be true, as Dr. Lindley (following Du
Petit Thouars,) supposes, that it does not originate from the descend-
ing sap, but is sent down ready formed from the leaves, we should
be disposed to remove it from the class with which it is usually
associated. Some, however, regard lignin as the matter deposited
within the fibre, not as the substance of the tube itself

The circulation of the latex or nutritious fluid, which has been
particularly described by Schultz, seems to approach pretty closely
to the capillary circulation of animals. We have already mentioned,
that there is a difference of opinion as to the nature of the canals in
which it takes place; but there is now no doubt of the fact, that an
extremely rapid movement of fluids goes on in these passages, in an
uninterrupted current passing from one set of vessels to another.
As this circulation was first witnessed and described in plants with
milky juices, it was supposed by some to be confined to them;
hence De Candolle considers it rather in the light of a peculiar local
movement. It has been rendered probable, however, by more
extended researches, that it is common to all descriptions of plants,
and is therefore to be regarded in the light of a general circulation.
The currents are very inconstant in their direction, and sometimes

* Turner's Elements of Chemistry, 5th Edit. p. 782.

168 VEGETABLE PHYSIOLOGY.

stop and recommence suddenly. The causes which produce the
movement are quite unknown ; it must be totally independent of
the impulsion of the spongioles, which can only be supposed to
influence the ascending current; it does not seem due to any con-
tractile power in the vessels ; and it will continue for a considerable
time in detached fragments of, a plant. The action is suddenly
checked by cold, and again goes on when the temperature rises;
by a strong electric shock also the motion is arrested. Further
researches are wanting on this subject; but what is already known
would seem to confirm the views of those physiologists who
regard the capillary circulation in animals as partly independent of
the heart.

The excretions of plants by their roots, the nature of which has
been so successfully investigated by M. Macaire, seem to correspond
in character with their peculiar juices, and may be regarded as
merely separated from them, in the same manner as (there is now
good reason to believe,) the excretions of animals are separated
from their blood.* It is probably to the effects gf the excretions of
one family upon the roots of another, rather than to any peculiarity
in the nature. of the aliment required by each, that we are to attribute
the influence of particular crops upon the soil in preparing or in-
juring it for the growth of other vegetables. Thus, plants of the
family Legumenosse, which excrete a large quantity of mucilage,
prepare or improve the soil for the graminese; whilst the papave-
racese, which excrete a matter analogous to opium, are notoriously
injurious to either. If an extensive series of facts of this kind
should be established by experiment, it. is obvious that the princi-
ples of agriculture might be much improved by their practical ap-
plication.

It is perhaps in the study of the function of reproduction that
vegetable and animal physiology are most capable of being advan-
tageously conjoined. In the simplest forms of plants, composed of
aggregated vesicles, each cell may be regarded as a distinct indi-
vidual being capable of maintaining an independent existence.
Here then the processes of nutrition and generation are united, and
nutrition may well be called "a perpetual generation." As we I'ise
in the scale, the aggregated vesicles lose a portion of their individu-
ality, the general structure assumes a more determinate form, and a
special generative apparatus begins to be evolved ; but, even in the
higher forms of the Protophyta, there is often no distinct line of
demarcation between the nutritive and reproductive portions of the
general surface. In the higher cellular plants, however, a more
complete separation takes place; but, though the anatomy of their
generative system has been attentively studied, and made the basis
of classification, little is known of its physiology. In many cases,
besides the spores, which are homogeneous masses of cellular

* Alison's Supplement to Physiology, p. 36.

VEGETABLE PHYSIOLOGY. * 169

substance acting like seeds in reproducing the species, the plant
propagates itself by gemmse, which may be considered analogous
to the leaf-buds of the Phanerogamia, The minuteness of the spores
and the universality of their diffusion will probably account for
most of those phenomena attributed by some to equivocal genera-
tion ; and, for a very able discussion on this subject, we may refer
our readers to the Library of Useful Knowledge, page 118. In
plants having a distinct sexual system, we observe the two modes
of reproduction in their most perfect or specialized form ; the one
connected directly with nutrition, and the other as it were in opposi-
tion to it. Each bud of a tree may be regarded as, in some sort, a
distinct individual, partly depending on and partly contributing to
the general system; but, if removed from it, and placed in circum-
stances favourable to its growth, it is capable of developing all the
organs necessary for its support. Hence, the increase of the size
of a plant by addition to the number of its buds may be regarded as
involving the functions both of nutrition and reproduction ; and
this increase is directly dependent on the quantity of aliment which
it assimilates. The development of the special organs of repro-
duction, on the other hand, only takes place when the plant is not
so highly supplied with nutriment as to occasion the growth of new
buds; but it is most interesting to observe that every one of these
organs, however various in external appearance, is produced from
the same elements as the leaf, and is capable, under particular
circumstances, of reverting to that form. We cannot at present
enter fully into the theoretical structure of flowers, which is ably
discussed in Dr. Lindley's Introduction to Botany ; and we must
content ourselves with stating the fact that the leaf may be traced
through the successive forms of bract, sepal, petal, and stamen,
until we arrive at the pistil, whose carpels are manifestly composed
of a leaf with its edges folded together. Each of these organs is
capable of changing into any other which is intermediate between
itself and the leaf, or of at once assuming the form of leaf; and
accordingly we find in monstrous flowers, some of which are per-
manent varieties, numerous malformations of this kind, which
distinctly prove the origin of the different appendages. The
rudimentary or metamorphosed leaves which constitute the parts
of a flower are subject to the same laws of arrangement as ordinary
leaves, the tendency of which is to arrange themselves in a spiral
round their axis of growth ; but, when the latter is not developed,
a vertical is formed, as in the ordinary structure of flowers, which
normally consist of four or more such whorls. Hence every
flower with its peduncle and bracteas, may be regarded as a meta-
morphosed branch. Even the ovules which are developed at the
edges of the capillary leaves, which form the placenta, occasionally
assume the form of leaf-buds, and then bear a strong analogy with
the buds formed upon the margin of some true leaves, such as those
of Bryophyllum.

170 VEGETABLE PHYSIOLOGY.

The mode in which impregnation is effected in vegetables is
highly interesting. When the pollen is conveyed to the stigma by
the bursting of the anther, the agency of insects, or other means,
its outer coat soon ruptures, and long slender tubes are protruded
through it, which find their way downwards, through the lax cellular
tissue of the stigma and style, to the ovarium. The foramen of the
ovule, previously to impregnation, is of considerable size : and it
appears probable that in all cases it is presented by the adjustment
of the ovule, either to the placenta or to that point of the ovary by
which the pollen-tubes afterwards enter, so as to receive the direct
fertilizing influence of the pollen granules. M. Raspail, however,
thinks proper to deny the statements of this process, which were
first made by Brown, Amici, Brongniart, and Ehrenberg, and which
have been since verified by many observers. We cannot understand
the grounds on which M, Raspail bases his assertion, that the contact
of the pollen with the stigma is all that is necessary for the ferti-
lization of the ovule; since any one possessed of a good microscope
and a little patience may satisfy himself of the passage of the pollen-
tubes down the style in the Asclepiadese, although he may not be
able to trace their entrance into the ovarium. In the Coniferse,
however, when no stigma or style intervenes, the pollen-tubes have
been seen to penetrate the bottom of the nucleus, when they evacuate
their contents ; and the evacuated matter soon forms itself into a
bag, which eventually contains the embryo. We think it not im-
probable that the early development of the ova of all the more
highly organized beings may be eventually reduced to the same
type, as has already been accomplished with regard to those of
mammalia and birds. Considering the earliest state of the embrya
of animals and vegetables as analogous to the simplest permanent
forms of their respective kingdoms, and knowing how nearly the
latter approach one another, we should expect to find a correspond-
ing approximation in the former, especially as the life of the fcBtus
until birth may be regarded as almost purely vegetative. Of the
further development of the embryo in plants we have already
spoken.

The productions of hybrids in plants is readily effected by the
application of the pollen of one species to the. stigma of another
nearly allied to it. Almost endless varieties may be thus produced ;
but mules are seldom fertile, except with one of their parents. Many
plants, which have been described as distinct species, are either
accidental varieties or mules between two varieties; and this fact
leads us to doubt whether mules, fertile of themselves, are ever
produced between two really distinct species. We are aware that
the gardener would bring forward many instances to the contrary ;
but it must be recollected that a very large number of the plants
described as distinct species have in reality a common origin, and
are therefore to be regarded as belonging to the same natural
species, though artificially divided. The tendency of some plants

VEGETABLE PHYSIOLOGY. 171

to produce varieties is so great, that many South American speci-
mens, whose history was not known, have been described as distinct
species, until it was found that their seeds produced each other
indiscriminately. When two permanent varieties differ strongly
in form or colour, so as to be regarded as distinct species, which is
frequently the case, an immense variety of fertile mules may be
produced between them ; and it is by such an intermixture of breeds
that the races of edible fruits and vegetables have been brought to
so high a degree of perfection. If any instance of fertility in true
hybrids ever occurs, (of which some instances are on record in
animals,) the power appears to become extinct in a few generations.

We intended to dwell at some length on the elementary vital
properties of the tissues of plants, with the view of investigating
how far they may be regarded as analogous to those of animals :
our limits, however, allow us to say but little on this subject. All
parts of living plants may be regarded as possessing the property of
excitability, or irritability, in its most extended sense, exhibiting
the various manifestations of life under the influence of external
stimuli, and being totally dependent on them for their continuance.
In this point of view, they afford to the physiologist the means of
tracing the effects of vital stimuli upon organization, more imme-
diately than he can observe them in animals, since there is no good
reason to believe that the results are complicated in plants by the
influence of a nervous system. The spontaneous motions which
occur in plants are generally to be attributed simply to the elastic
and hygroscopic properties of their tissues; but the sudden con-
tractions which take place in many instances from the direct appli-
cation of a mechanical stimulus, would seem to indicate the existence
of a property not altogether unlike the irritability of muscular fibre,
but insusceptible of any other kind of stimulus.

It is a very interesting subject of inquiry how far the instinctive
actions of animals may be regarded as analogous to those of plants.
In the systems of the latter, we may observe the direct " respondence
of their organization to external agencies;" and the same would be
true of the organic functions of animals, if we adopt the opinion of
many physiologists, that they are not immediately dependent upon
innervation. The powers which Bichat termed (perhaps somewhat
incorrectly) organic sensibility, and insensible organic contractility,
may thus be considered as the proximate causes of the manifestation
of vital instincts both in plants and animals, whatever we may
think of their relation in the latter with the ganglionic system of
nerves; and we might then regard the obvious motions of plants as
occasioned by the exaltation of these powers in certain cases; whilst
the external instincts of animals, requiring for their manifestation
the exercise of the organs of voluntary motion, are obviously de-
pendent upon the nervous system, by which alone these organs can
be made to act. But, as Mr. Kirby justly remarks, "can we not
conceive that the organization of the nervous system may be so

172 VEGETABLE PHYSIOLOGY.

varied and formed by the Creator as to respond in the way that he
wills to the impulses of the physical powers of nature, so as to
excite animals to certain operations for which they were evidentl}''
constructed?" The subject upon which we have thus cursorily
dwelt is one which offers a wide field for investigation ; and we
hope that we have succeeded in showing that such an inquiry may
be conducted most philosophically, and with the greatest prospect
of success, when it is made to embrace all the classes of objects in
which vital phenomena are manifested.

PUBLIC HYGIENE/

M. DucHATELET is already known to our readers, as the author
of the remarkable work on Prostitution, which has been reviewed
in the two last numbers of this Journal. t The present one consists
of a series of memoirs on subjects connected with public hygiene,
more especially in reference to the State of Paris and its environs.

A short biographical sketch of the author is prefixed by his friend,
M. Leui'et, to whom was confided the publication of the work.
From this we learn that M. Duchatelet, renouncing the profession,
in which he had fair hopes of a bright success, had devoted the last
fifteen years of his life to the prosecution of a calling, which, although
dangerous as well as repulsive and even disgusting, must be allowed
to be of great importance, and one on which the health of large
cities, and the comfort and convenience of individuals so much
depend. He assures us himself, that he had traversed and examined
almost every sewer in Paris, had conversed with almost all the
workmen, had assisted them in their labours, had accompanied them
to the most infected spots, had spent days and even weeks in the
Augean stables of filth and nastiness in the neighbourhood of Paris
— Montfaugon and Bondy — had visited repeatedly all the workshops
of the tanners, the preparers of animal grease, glue, music strings,
Prussian blue, &c. and that he thus acquired an intimate acquaintance
with almost every hole and corner of the metropolis. He was long
one of the most efiicient members of the council of health (Conseil
de Salubrite), and repeatedly applied to by Government for infor-
mation relative to many of the public works. Numerous were the
reports which he drew up and published at difierent times. The
substance of these will be found in the two volumes under review.
We propose now to give a short analysis of the most important of
these. The first, to which we shall call the attention of our readers,
is one on the past and present state of the dissecting-rooms in Paris.

A historical sketch of these, during the last century, is detailed
with great minuteness. He mentions many curious particulars res-
pecting the extreme difficulty of prosecuting anatomical studies in
Paris, and the numerous obstacles which the teachers experienced
in procuring bodies for dissection, during the early and middle parts
of the last century. We were not aware, until we perused M. Du-
chatelet's work, that there had been no public or recognized amphi-

* Hygiene Publique, par A. J. B. Parent-Duchatelet. 2 Tomes, pp. 553 and
704. Bailliere, 1836.
■j- Medico-Chirurgical Review, Nos. L. & LI.
m 17

174 PUBLIC HYGIENE.

theatre of anatomy there, before the time of the great Dassault. To
this distinguished surgeon was due, it appears, the merit of having
overcome the national prejudices againstthe prosecution of dissecting,
and of having first established openly rooms for the purpose. His
example was followed, a few years afterwards, by several of his pupils,
among whom we may enumerate Dubois, Lallemand, Bichat, and
Boyer. All these celebrated men were teachers of anatomy, and
superintended for many years private dissecting-rooms.

At this period, the supply of bodies must have been scanty and
not easily obtained. Very few were procured from the hospitals ;
and hence recourse was necessarily had to the church-yards, which
were then numerous within the walls of Paris. The state of the
dissecting-rooms was, from all accounts, most shocking and repulsive.
They were small, miserably inconvenient, being often situated in
the attics of an inhabited house, filthy beyond description, and there-
fore not a little offensive to the neighbourhood. Complaints upon
complaints had been made against the continuance of such a nuisance,
and the ]ocal police of the town had repeatedly made atempts to
correct and improve the state of things. But what with the state of
agitation and confusion which prevailed for so many years, before
Bonaparte seized the reins of goveirnment, and other causes which
M. Duchatelet alludes to, it would seem that no effectual step towards
any change was taken until the year 1S06, when a commission was
instituted to examine into the state of the medical schools, and more
especially of the dissecting-rooms throughout Paris. The late Baron
Dupuytren was one of the number, and to him was entrusted the
charge of drawing up the report. Certainly none was better qualified
to advise Government on such a subject. He himself had been for
many years a teacher of anatomy in the metropolis, having been first
the assistant, and then the successor of the immortal Bichat. The
most important suggestion in the report was that, wherein the com-
mission recommended that all the small private schools should be
thenceforth abolished, and consolidated, as it were, into two great
central establishments ; one to be appertaining to the faculty of medi-
cine, the other to be attached to the Hopital La Pitie. We are told
that Napoleon himself took considerable interest in these affairs, and
that he had designed some important changes in many of the medical
institutions of his metropolis. Certain it is, that about this time,
1806, he had given orders that the present decayed building of the
Hotel Dieu should be demolished, with the view of reconstructing it
upon a grand and more commodious design, not only as a hospital,
but also as a great central school of instruction.

This project, like many others of the same mighty architect, has,
it is well known, never been carried into effect. Even the vile, fil-
thy dissecting-rooms, of which there used to be so many around the
hospital, continued to exist for several years afterwards ; and it was
not until 1813 that M. Pasquier, then the Prefect of police, issued
the ordinance, by which all the private schools were abolished, and
the suggestion of the commission was carried into effect — viz. the

PUBLIC HYGIENE. I75

establishment of only two greatanatomical amphitheatres. For some
time previously a very important change, in the mode of procuring
subjects for dissection, had taken place. We have already mentioned
that, in the time of Dessault, and of his immediate successors, the
cemetries within the barriers had yielded the supply of bodies for
the anatomists ; but, after Napoleon had ordained the removal of all
the church-yards to the outside of the walls, and the disinterment of
bodies was prohibited by severe penalties, the bodies of those who
died in the hospitals and hospices of the metropolis were appropriated
for the purpose.

The centralization of the dissecting-rooms gave great offence to
many of the young teachers and professors of the private schools ;
and various attempts were made to evade the enactment. These at-
tempts have gradually succeeded ; and hence, at the present time, there
are dissecting-rooms, not only at the La Pitie Hospital, and at the
Ecole de Medecine, but also at the Salpetriere, Maternite, St. Louis,
Beaujon,and Charite Hospitals. From M. Duchatelet's inquires, it
appears that between twelve and fourteen hundred bodies are dis-
sected annually at the La Pitie rooms, and not fewer than a thousand
at those of the School of Medicine. Most of the English, and other
foreigners, who go to Paris for anatomical instruction, dissect at the
former.

Our author examines at great length the question, whether the
existenee of anatomical amphitheatres in a city is at all injurious to
the public health ; as, some years ago it was often urged against
these establishments, that they were so many "foci" of infectious-
emanation. He has quite satisfied himself that there is not a shadow
of truth in this statement ; and among other argum^ents, he appeals
with confidence to the healthy state of the Hotel Dieu in former
years, when this hospital was surrounded by numerous dissecting-
rooms, some of which were even within its walls. He next adduces
the testimony of a great number of eminent authorities to confirm
his opinion. The first he quotes is the lateM. Lallemand, who ha&
left us an account of the dissecting-rooms first established by Dessault.
They were, it appears, situated on the top story of an old decayed
house. The number of bodies usually on the tables was from 50 to
60, and the number of pupils 200 or more. The rooms were very
seldom cleaned, and even the debris of the bodies was not removed
oftener than once a month. Nothing could exceed the abominable
stench diffused over the immediate neighbourhood ; and yet, says
M. Lallemand, we never heard of any diseases, which might be fairly
attributed to the presence of the dissecting-rooms, either among the
students themselves, or among the inhabitants of the adjoining houses.
Dessault himself used to say, that he really believed that the odorus
air of his dissecting-rooms saved him from attacks of epidemic and
other disorders, of which those hospital physicians and surgeons,
who seldom or never dissected a dead body, seemed to be much
more susceptible than himself He took pleasure in repeating the
old saying — " morte la bete, mort le venin ;" and therefore he did

176 PUBLIC HYGIENE.

not feel at all desirous, he said, to alter the state of the rooms under
his charge.

M. Duchatelet next appeals to the testimony of Dubois, DupuytreOj
Boyer, and of a host of others still alive, who have been, or still are,
teachers of anatomy. They all agree in opinion, that it is quite an
error to suppose, that the air of a neighbourhood is ever contaminated
— so as to induce disease — by the emanations from dissecting-rooms,
or that the students ever suffer from breathing the impure air of
these places.

M. Duchatelet applied to M. Andral, among many others, for his
opinion on this subject. The following is an extract from his letter :
— " As to the diseases which medical students contract during their
dissections, we have no good grounds for attributing them to cada-
veric emanations. Gastroenterites, meningites, and typhoid fevers,
are very frequent among the students during the first year of their
stay in Paris ; but these diseases depend so little upon the mere cir-
cumstance of the sejour' of the students in the dissecting-rooms, that
they are more common among those who have not begun to dissect.
Indeed the mortality among the medical pupils is certainly not
greater than am.ong an equal number of any other class of young
men. The fatigues of study, the late hours, the intellectual exertion
at home for the concours, &c. are much more hurtful to the constitu-
tion, than the labours of the dissecting-room. I have taken the
trouble to ascertain the general health of the servants of the amphi-
theatre— ^and some of them pass day after day there without once
going out — and it appears that they are quite as healthy in every
respect, as other men."

With respect to the health of the students themselves, M. Ducha-
telet has taken great pains to discover, whether there are any good
grounds for supposing that it is affected by the air and the labour of
the dissecting-room. According to his account, the most frequent
complaint among these youths is dyspepsia, attended often with
colicky pains and diarrhoea. But these symptoms are, says he,
attributable much less to their engagements in the dissecting-rooms,
than to the imperfect or improper diet, which the " res angusta
domi" imposes upon many of them. Not a few of the French
students, especially those who arrive from the provinces, are but
scantily provided with even the absolute necessaries of life. M.
Duchatelet assures us that he has known several who have lived for
weeks, aye and months too, upon stale bread, and an occasional glass
of brandy.

It may be worth while to notice also the usual good health of the
servants of the anatomical theatres. Many of them live within the
premises ; yet they do not suffer any direct inconvenience ; and it
has been often remarked that these men are singularly exempt from
febrile diseases.

The mention of these '^gar^ons" leads M. Duchatelet to allude to
a practice, which seems to have been, some years ago (and may be
still), very common among them, but which probably is quite un-

PUBLIC HYGIENE. 177

known to most of our readers. It appears that they were in the
habit of collecting all the fat from the dissected bodies, and selling
it to the enamellers, 'manufacturers of pearls, and other artisans, who
require that the lamps, which they use at their work with the blow-
pipe, should have a steady strong flame. Human fat, we are told,
is better suited for this purpose, than that of other animals, from its
remaining more uniformly fluid. Horse and dog grease is what is
commonly used ; and, as such, the fat from the dissecting-rooms
had been sold. M. Duchatelet mentions that two thousand litres
of human fat were found, some time ago, in the possession of one
of the servants attached to an anatomical amphitheatre. This man
confessed that he intended to have sold it, and that for several years
he had made a good deal of money in this way.

The police applied to the Academy for information, on the means
of distinguishing human fat from that of other animals. It seems
from the following extract of the report, drawn up by Dupuytren at
the time, that the question does not admit of an easy solution: —
"Les graisses d'homme, de cheval,etd'ane nepeuventetredistinguees
entre elles, parcequ'elles ont toutes une coleur unecoleur jaune, une
concrescibilite tres faible, une tres grande fetidite, et qu'elles se pre-
cipitent en globules."

But to return from this digression, to the question as to the influ-
ence of the exhalations from putrid animal bodies on the health of
those engaged in dissection, M. Duchatelet mentions that, it has been
conjectured by som.e, that the effluvia from human bodies are not so
injurious as the emanations from those of the lower animals. It
appears, however, that this idea is not warranted by experience.

M. Rousseau, who has, for six and thirty years, been the super-
intendent of the anatomical preparations at the Jardin des Plantes,
assured M. Duchatelet, that neither he, nor any of his assistants,
has ever sufiered from their occupations, even during the Summer,
although the bodies of the animals dissected there are often exces-
sively putrid.

Our author, not satisfied with the preceding authorities, appeals
to the testimony of Mr. Lawrence of London, contained in a letter
which this eminent anatomist wrote many years ago, to Dr. Bancroft,
and which is cited by Dr. Warren in the Boston Med. and Surg.
Journal. Mr. Lawrence mentions the case of the servant, who, with
his family, lived for ten years under the dissecting-rooms at St.
Bartholomew's Hospital without suffering the slightest derangement
of health.

The means, which M. Duchatelet proposes for the purpose of
purifying anatomical rooms, and to keep them in a siveet state, it is
scarcely necessarj' to notice ; as, in truth, they only consist in re-
commending the cleanliness, free ventilation, the removal of all the
debris as speedily as possible, and the use of the chlorides to the
floors and tables.

He has described and delineated a dissecting-table of a particular
construction, which may be of use, when it is an object to preserve

17*

178 PUBLIC HYGIENE.

a body from putrefaction for a great length of time, or to examine
one already much decayed. This table is boarded all round, and
perforated with numerous holes, which communicate with a flue
terminating in the chimney.

The effect of this contrivance when there is a fire in the grate, is
to cause a continued current of air to pass from within the room
towards the chimney. The body on the table is thus exposed to a
constant ventilation ; and, moreover, the offensive effluvia are pre-
vented from being diffused through the air.

From the subject of the dissecting-rooms, we pass on to the
report of our author on the recent disinterment of a number of
putrid bodies, from the vault of a church in Paris.

As soon as the uproar and bloodshed of the three "glorious days"
had ceased, it became one of the earliest duties of the Provisional
Government to provide interment for the unfortunate victims of
the struggle.

In some of the streets the dead bodies lay in dozens, heaped and
piled together ; and already, in consequence of the hot weather,
many of them had become most offensively putrid. There were
upwards of two hundred deposited at the Morgue, and almost as
many under the Pont Notre Dame.

At first it was proposed to dig a large grave for these in the
Gardens of the Archbishop's Palace, which is situated close to the
Cathedral ; but the officers of the Hotel Dieu very properly objected
to this proposal, as the air of the hospital might have been thereby
contaminated, and the health of the inmates seriously injured.
The bodies, therefore, were put into barges, and floated down the
river as far as the Bridge of Jena, opposite the Champs de Mars,
and there buried.

M. Chevalier had the charge of superintending the removal ; and,
by the judicious arrangements which he made, not one of the work-
men employed in the offensive occupation, suffered. Large quan-
tities of chloruret of lime, both in its dry and its liquid state, were
used for the purpose of disinfection.

While these steps were taken at one part of Paris, the people in
different quarters had, of their own accord, dug deep pits, wherever
there was a vacant spot, and had buried the bodies in heaps. No
injurious consequences ever followed, as far as we know, from this
proceeding. But in one neighbourhood, that of the Rues Mont-
martre and Mont-orgueil, a number of bodies having been collected
together under the portico of the church of St. JSustache, it was
unfortunately resolved to deposit them in the vaults underneath.
There they lay for some weeks, until the air of the church became
so offensive, that no service could be performed in it, and the
inhabitants of the adjoining houses began to complain of the fetid
emanations. The subject was referred by Government to the
Council of Health, for their advice as to what steps ought to be
taken. At first it was proposed to do nothing more than to re-open
the vault, and to introduce a quantity of quick-lime over the spot

PUBLIC HYGIENE. 17g

where the bodies had been thrown in, for the purpose of accelerating
their decomposition, and also of counteracting, it was hoped, the
offensive effluvia. But this inefficient measure was very properly-
rejected. A committee, which contained among its members M.
Labarraque, the famous chemist, M. Andral, and our author, was
deputed to ascertain particulars, and to suggest what should be done.
These gentlemen quickly determined on the necessity of removing
the bodies, however decayed and putrid they might be. M. La-
barraque proposed to superintend himself the operations. Having
had all (the windows of the church opened, he had a number of
buckets, full of the solution of the chloruret, placed in different
parts. The workmen also washed their hands and faces well with
it. When an opening was made into the vault from the floor of
the church, a quantity of the chloruret was thrown in, and one or
two of the workmen (servants employed at the Morgue and in the
public sewers) descended. M. Duchatelet immediately followed
them.

He tells us, that the stench was not nearly so offensive as might
have been expected. The floors and walls of the vault, and the
dead bodies also, (some of which were excessively putrid,) were
well washed with the chloruret. The bodies were then enveloped
in separate pieces of coarse canvas which had beeen steeped in the
solution, and were hoisted up into the church. The whole business
was completed in little more than two hours, and not a single
person engaged complained even of temporary inconvenience. The
bodies were then conveyed to the great cemetery at Montmartre,
and were all (43 in number) buried in the same grave.

The next memoir, which we propose to notice, is rather a lengthy
and tedious one, on the question, how far putrid effluvia affect the
wholesomeness, and tendency to decomposition, of sound meat and
other articles of food. The motive, which M. Duchatelet alleges
for his minute examination of this subject, is that it has been re-
peatedly stated, even by professional and scientific men, that the
health of the inhabitants, who live in the neighbourhood of slaughter-
houses, dissecting-rooms, public sewers, &c., has suffered, not only
from respiring a vitiated atmosphere, but also from their food be-
coming quickly corrupted.

To settle this question, he visited almost every hole and corner
of Paris — such as the neighbourhood of that most abominal sewer-
like stream, the Rivere de Bievre near the Gobelins ; many of the
laystalls, and especially that incomparable stable of filth and nastiness,
the enormous slaughter-houses at Montfaugon, where not only be-
tween 12 and 13,000 horses are killed yearly, but almost all the
ordure of Paris is collected together; the abodes of the workmen
employed in the disgusting occupation of making music strings
from the intestines of animals ; not to mention the houses of the
servants engaged in the Amphitheatres of Anatomy. The result of
all his inquiries has been, that the almost constant effluvia of these
places has very little or no effect in corrupting, or otherwise affect-
ing, the wholesomeness of any article of food. Meat, broth, and

1 80 PUBLIC HYGIENE.

vegetables, seem to be as easily preserved there, as in the healthiest
and most airy districts of the metropolis.

Not content with this mode of inquiry, our indefatigable author
carried on for a period of five months a series of direct experiments,
in his own laboratory, to determine the question under considera-
tion. He kept different articles of food, such as blood, milk,
chicken-broth, mutton-broth, beer, wine, gruel, solutions of starch
and gum, as well as meats of various sorts, surrounded with vessels
filled with the most putrid and putrefying substances; and he found
that, although they all (but in different degrees) acquired an offen-
sive odour, they speedily lost this on being exposed to the air; and
that they did not become decomposed sooner than other portions of
the same substances, which had been kept in a pure place. It may
be useful to know that, in conducting these experiments, M. Du-
chatelet discovered, that the substances might be preserved even
from acquiring the slightest offensive odour, by covering their
surface with a thin layer of oil ; and also, that boiling will effectually
remove it, after it has been acquired. The thicker and more viscid
a fluid is, the less readily does it become impregnated with the fetid
effluvia. Hence pure water is most quickly tainted ; whereas
solutions of gum, starch, gelatin, &c. are so, very slowly. We
have, however, already stated that this taint may always be removed
by exposing the fluid afterwards to the free air, and especially by
boiling. It thus appears that putrid emanations act merely as any
other odoriferous substance : the effluvia penetrate more or less
easily the substance which may be exposed to their influence; but
they do not cause any permanent or molecular changes in it, nor do
they seem to accelerate, in the slightest degree, the tendency to
decomposition.

M. Duchatelet has suggested a simple and very ingenious con-
trivance for the preservation of meat, and of other corruptible
substances. He finds fault with the common plan of merely sus-
pending them from the ceiling, as if the air was cooler there than
nearer the floor. If, however, a tray holding pieces of ice, or a
vessel of iced water be hung over them, a current of air from above
downwards, and vice vej^sa, w'lU beoccasioned : the cooledairdescend-
ing, and being replaced by a volume from below. He also suggests
the use of a table, constructed on the same principle as the dissecting-
table, which we have already described. These hints may possibly
be useful. M. Duchatelet mentions, that one of the famous shops
for "comestibles," in the Palais Royal, is provided with a table,
such ^s he recommends.

Our attention is now called to another memoir, which although
long — extending to 130 pages — is, nevertheless, very interesting.
It is occupied with a minute account of those disgusting, but very
necessary, establishments for the slaughter of old decayed horses,
and for the flaying of all the dead dogs and cats, not only in Paris
itself, but also such as are brought from several miles round. These
establishments are called "chan tiers d'equarrissage ;" and, from

PUBLIC HYGIENE. 181

what our author says of them, it would seem that the filth, stench,
and Hastiness of them is most insufferably horrible. Addressing
his countrymen, he says: "You may well be proud of your markets
and of your abattoirs, and of your fountains which wash and refresh
your streets, and of your sewers which dry and cleanse them ; but
is it not too bad, that every time you go out, and come into your
city, 'qui se pretend la capitale du monde civilise' (!), you run the
risk of being suffocated by the vile emanations from the slaughter-
houses and heaps of ordure, 'don I'aspect seul fait reculer d'hor-
reur?' "

The largest of the "chantiers d'equarrissages" is situated at
Montfaugon, a mile or so from the north-east extremity of Paris.*
There is another, of smaller extent, on the opposite side of the river,
not far from the Hospice de la Salpetriere. Various expedients have
been proposed, not only by private speculators, but also by the
public authorities, to obviate and counteract, if possible, the horrible
loathsomeness of these establishments. At one time it was ordered,
that the carcases of the beasts should be stripped at once, and that
all the flesh, fat, and garbage should be daily buried in deep pits.
But the proprietors, many of whom have made immense fortunes,
petitioned against this most oppressive (at least to them) regulation.
They had been in the habit not only of melting all the fat, which
fetched a high price, but also of selling the flesh, bones, &c. to the
farmers, for the purpose of manure ; not to mention the profitable
sale of the garbage, hoofs, &c.

In 1812, three gentlemen, who had a high name as most able
manufacturing chemists, suggested an ingenious plan for diminishing
the offensiveness of the "chantiers." It consisted in hanging up
all the stripped flesh, &c. in leaden chambers, and there exposing it
to an atmosphere of steam for several hours. The fatty matters,
being melted by the heat, drop down, and collect into a stream ;
while the fleshy parts are sodden, and therefore not liable to putre-
faction. They are then to be pressed by a machine into large
pieces, which are ready for sale to the sellers of dog and cat meat,
to the farmers, and to the manufacturers of Prussian blue, &c.
The Emperor Napoleon granted letters-patent to these gentlemen ;
but we are not informed whether they have ever carried their
project into effect.

In 1822, M. Dupuy, the professor in the Veterinary College at
Alfort, petitioned Government to be appointed Inspector of the
various slaughter-houses in and about Paris (to which, he states,
there are annually brought between 7 and 8,000 horses — 12,000

* Several years ago, a company of " equarrisseurs" was set going in anollier
district of Paris, and for a considerable time their affairs appeared to be very
thriving. Unfortunately, however, for the concern, it was discovered that the
pork and sausagemongers were in the habit of keeping an immense number of
grunters near the "chantier," for the purpose of feeding them with the vile gar-
bage of horse, dog, and cat flesh. For several months, Paris might have been
taken for a metropolis of Jews or genuine Musselmen; not a sausage or piece of
pork were to be seen any where !

182 PUBLIC HYGIENE.

dogs, and 6,000 cats*), for the purpose of prosecuting his researches
in comparative pathology; but this request was not complied with.
One of the abominable evils resulting from the "chantiers d'equar-
rissage" around Paris is, that the flesh of the dead horses has been
secretly sold as food to the inhabitants, on many occasions. During
the first revolution, it is well known that there was, for a con-
siderable length of time, a great scarcity of provisions ; and we have
the authority of M. Huzard, who had ample opportunities of ascer-
taining the truth, that a large portion of the animal food, consumed
during that period in Paris, consisted of horse-flesh. In 1803, the
surreptitious sale of this was again discovered ; and repeatedly in
ISll, when, it is well known, all articles of food were exceedingly-
expensive, and there was much want and distress among the lower
orders. The commissioners of police seized large quantities in the
houses of several of the petty victuallers, in the indigent quarters
of the metropolis. M. Pasquier, at that time head magistrate of
Paris (Prefect of police), applied to the council of health for their
opinion, whether the use of horse-flesh, as food, is injurious to
health, or not. Like many other commissions, the one appointed
to report returned a very dubious answer. M. Pasquier, therefore,,
acted upon his own judgment, and positively interdicted the sale of
the flesh from the "chantiers d'equarrissage" upon any account or
for any purpose. The very strictness of this injunction unfortu-
nately frustrated its intentions. The vast number of dogs in and
around Paris, not to mention the carnivorous animals in the Jardiii
des Plantes could not, it was^ alleged, be fed in any other way, hut
by the meat obtained from the horse-slaughter-houses; and hence
permission was afterwards granted for the sale of this meat to certain
persons, but only for the purpose now mentioned.

■It seems, however, that as recently as 1817, there was a quantity
of horse-flesh sold for human food in Paris; and in 1835, the com-
mittee, appointed to inquire into the state of the various laystalls
about Paris, actually proposed to Government to permit the sale of
horse-flesh for human food under certain regulations. This strange
suggestion was very properly rejected. t It was, however, again

* This statement of the number of beasts taken to the "chantiers" differs, it
will be noticed, from that given by our author. We are inclined to believe that
M. Duchatelet may be depended upon for the accuracy of all his assertions.

f Our author, indeed, seems rather inclined to permit the sale of horse-flesh,
under certain restrictions. He tells us, that many of the men employed in the
great slaughter-house at Montfaucon make use of it constantly, and that they
do not suffer any bad effects from the practice. In Denmark, and also, we be-
lieve, in Sweden, the public sale of horse-flesh is authorised ; and Baron Larrey
informs us, in his great work on Military Surgery, that the wounded of the
French army, in the Egyptian and Russian campaigns, were fed for weeks and
even months upon horse-flesh, without any injury to their health. "The flesh
of the horse (says he) makes a very good soup, especially if some lard is added
to it; or it may be broiled, or prepared as 'bojuf a la mode,' mixed with proper
seasoning. The liver, too, was highly esteemed by our soldiers in Russia.
During the siege of Alexandria, the health of the troops was mainly preserved
by the regular supply of horse-meat to them. It contributed very materially

PUBLIC HYGIENE. 183

proposed by some, after the last revolution in 1830, when great
numbers of the poorer classes were quite destitute and starving.
But although the practice was prohibited, it would seem that, even
in the present day, a large quantity of horse-meat is sold in Paris.
The following are the words of one of the commissioners of police,
published not long ago :

"II est de notoriete publique que I'on vend, a raison de quatre
sous la livre, chez divers restaurateurs de la capitale, de la viande
choisie de cheval, nouvellement abattue; que ceux, qui ne peuvent
ostensiblement faire entrer dans le jour de cette viande, vont a une
heure, et k un lieu convenu, en jeter, par dessus les murs, des

morceaux considerables, qui sont tl I'instant ramasses Ceci

se pratique tous les jours."

It would seem, from what our author says, that even dogs and
cats are often sold in Paris for human food. His own words are :
'•We have never visited this establishment (the slaughter-house at
Montfaucon, appropriated to the skinning of these animals), without
finding a number of them 'ouverts, depouilles, ettrousses avec soin,
tout prets enfin a faire cuire pour le repas auquel ils devaient
servir." ! !

But to return to the more immediate subject of our inquiry, that
of the "chantiers d'equarrissage," we must refer such of our readers,
as may wish to know particulars concerning them, to M. Ducha-
telet's work. There is a minute description given of the immense
establishment at Montfaucon, in the immediate vicinity of Paris.
He estimates the number of horses taken there, either dead or to be
killed, at between 12 and 13,000 annually. A considerable pro-
portion is sent from the country, within several miles around Paris.
The account v^hich he gives of the wretched fam.ished animals led
there, in dozens, to be slaughtered, furnishes a sad commentary on
the mercenary unfeelingness of man ! The number is always
greatest towards the end of the year ; because then a number of the
poor animals, which had been regularly worked out during the pre-
vious Summer and Autumn, are not deemed by their masters worth
the expense of their keep through the Winter. They are therefore
condemned to the slaughter-house, where they usually fetch from
10 to 20 francs a head.

There are four different methods in which the animals are killed :
by blowing air into an [opened vein, by pithing, by bleeding, or,
lastly, by felling on the head. The third of these methods is the
one usually adopted. A long knife is introduced into the thorax,

to the stoppage of a scorbutic epidemic, which had appeared among them.
I repeatedly partook of the meat myself, and found it both palatable and nutritious.
" After the battles of Eylau and of Eslingen, the wounded were fed upon horse-
flesh for several days; and when, at length, oxen were procured, the soldiers did
not recognize the difference. The cuirasses of the cavalry regiments served as
utensils to boil the flesh in, and gunpowder was used in the place of salt, of
which there was a complete want in the camp. ' Ce bouillon fut d'une tres
bonne qualite.' Marshal Massena partook of the same fare, and highly approved
of it."

184 PUBLIC HYGIENE.

in the direction of the arch of the aorta which is almost always
divided : the animal staggers for a minute or so, then drops down,
and expires in convulsions.

The only inconvenience of this method is, that the animal some-
times does not fall down on the spot, where he stood when wounded.
Hence, when there are a number of horses crowded together in a small
space, the "equarrisseurs" very frequently employ the last-men-
tioned method, felling ; as the animal usually falls down on the spot.
The animal is quickly stripped of its hide ; the flesh is next cut off
from all the bones, and heaped together for sale; the viscera are
thrown together in large masses, and the carcass is then carried oflf
to a corner in the yard.

We have omitted to state that the hair of the mane and tail is
always cut off before the animal is killed ; but this, usually, has
been done before the beast is taken to the slaughter-house. The
hides are sent off to the tanners (most of whose establishments are
on the other side of the Seine, adjoining the filthy stream of the
Bievre, near the Gobelins) ; the flesh is divided into different
heaps, some for human food (!), others for dog, pig, and cat meat,*
and for the supply of the carnivorous animals in the Museum of
Natural History. Some of the large dogs, kept in and about Paris,
are trained to go by themselves to the slaughter-house, for a weekly
supply at a time. The men know them, and fasten a large piece of
the flesh round their necks, and off they go, thus loaded, to their
masters' houses. What is not disposed of in these manners is, along
with the garbage of the viscera, sold for manure, or to the manu-
facturers of Prussian blue, &c. The small intestines are sometimes
used for the manufacture of the large coarse gut-strings. With
respect to the blood of the slaughtered horses, M. Duchatelet ex-
presses his surprise that it is not turned to more profitable account.
Often it is allowed to flow on the ground, into which it soaks,
forming a compost of most disgusting fetor ; this is afterwards
mixed with the dung, and sold as manure.

If the blood was collected and separated, by stirring, into its liquid
and its solid part, the former might be advantageously sold to the
refiners of sugar, &c. and the latter, when dried, might be used for
the food of animals, and even of man (!), or to some manufacturers.
Most poultry will eat blood readily. A curious phenomena has
been observed among the hens in some of the " chantiers :" the eggs
which they lay have no shells. At present, the chief consumption,
of the fibrin of the blood (dried) is in the way of exportation, to
the colonies, for manure. The tendons and hoofs are used for the
preparation of glue, and in the manufacture of combs, &c. The
horse-shoes are sold either as old iron, or to be again used as shoes ;
and the nails are collected together and sent into the provinces,
where they are generally used " pour garnir les sabots" of the pea-

* We are also told that many of the poultry-feeders about Paris give horse-
meat to their ducks, geese, and fowls.

PUBLIC HYGIENE. 185

santry. The fat is collected into heaps, melted, and sold at a high
price to the enamellers, manufacturers of pearls, and in general to
those who use the blowpipe in their work. The flame of a lamp, fed
with horse-oil, gives a more steady flame, than with almost any
other. This oil is also used in the manufacture of soap, for softening
harness leather, and sometimes in the preparation of gas.

We have thus disposed of almost all the soft parts of the animal ;
and the reader may now inquire, what becomes of the bones. At
one time they were used, in great quantities, in the building of the
walls (.') in and around Paris, especially of such as surround the
marshes and gardens. The bones were mixed up with moistened
earth, which on drying was held together efiectually. These walls
were very common in the Faubourg Saint Marceau, and in the neigh-
bourhood of the Temple, and the Barrier des Tourneaux — places
near which the "chantiers d'equarrissage" have been usually situated.
Many of the walls have of late years been destroyed, for the sake of
the bones ; but not a few are still standing.

The broad flat bones are used for coarse cutlery, and in the manu-
facture of toys ; but the chief consumption of horse skeletons is by
the manufacturers of ammonia, of animal charcoal, &c. When de-
prived of their gelatin, the bones are ground down and then sold
for manure to the land.*

Having thus discussed the economical uses of the " chantiers,"
our author proceeds to examine into the health of the workmen en-
gaged in the disgusting occupations of these places. With his
accustomed zeal he has accumulated a great number of facts, to prove
that the men are quite as health)^, or even more so, than most others
of the lower classes.

We are told of the " sante la plus florissante" of the men, the
"sanle brillante" and the " fecondite remarquable" of many of the
women, and the "force et mine admirables" of the infants, who are
sometimes cradled " dans Pinterieur d'une carcasse, comme dant un
bergeau !" The same holds true of the manufacturers of gut-strings,
and of their families: they are in general remarkably healthy.
What is especially worthy of notice, is, that the men very seldom
suffer anjT- inconvenience from wounding themselves, while engaged
in their operations. The wounds, it seems, heal quickly ; and it is
rare that any case of carbuncle or of the "pustula maligna" occurs.
"We shall mention," says M. D. "only one other circumstance in
reference to the health of the workmen in the 'chantiers ;' and that
is, the remarkable exemption from illness, which they enjoyed,
during the destructive prevalence of the cholera in Paris. There
were far fewer patients admitted into the hopital St. Louis, which is

* Our author states, that in no district is there so large a consumption of
bones for this purpose, as in Yorkshire. The quantity of bones sent to that
country from London is quite enormous; amounting annually, it is said, to 33
millions of kilogrammes (a kilogramme is rather more than two pounds of avoir-
dupois weight).

m 18

18Q PUBLIC HYGIENE.

situated in the district of the ' chantiers/ than into any other hospital
in the metropolis."

We do not wish it to be supposed, that, by the statements which
we have now been making, we approve of the abominable nuisance
of these establishments : but still it is a duty, which we owe to the
public, to conceal no well-ascertained facts ; and certainly one of
these is, that the cholera affected scarcely any of the workmen now
alluded to.

But we must now leave the " chantiers d'equarrissage," and pass
on to another subject, which our readers may think to be still more
uninviting — the state of the " fosses d'aisance" in Paris. M. Du-
chatelet, however, animated by a most laudable zeal to improve the
condition of every class of society in that gay city, devoted much
of his time and of his attention to this subject. " He had not," says
his biographer, " the repugnance which these places naturally excite ;
I had almost said that he liked them (je dirois presque q'il les aimait) !
An anecdote told of him givesproof of this. Being present at a gay
fete in the Hotel de Ville, he could not help saying to one of his
friends, ' J'aime centfois mieux aller dans un egout que de venir a
cette reunion : on ne me verra plus ici!' Under such guidance, we
shall not hesitate to accompany him in his rambles.

The state of the " fosses d'aisance" in Paris is certainly one of the
greatest reproaches to the metropolis, which is so boastfully called
by its inhabitants "the centre and mart of civilisation and refine-
ment."

Many of our readers are perhaps not aware that, with the excep-
tion of a few insulated public buildings, such as the Palace of the
Tuileries, the Hotel des Invalids, the Bicetre Hospital, and two or
three others, no dwelling in Paris is provided with a water-closet
on the English construction : (latrine a I'Anglaise.) The reason of
this great defect is no doubt, because the public sewers of the place
are not numerous, and most of them are very imperfectly constructed.
There are only a few large ones, crossing the metropolis in different
directions to carry off the water and filth in the kennels of the streets,
and the fluid refuse of manufactories ; but the houses themselves have
no communication with these sewers by means of private drains.
Hence the only means, of getting rid of all the accumulated foul
water, is to throw it either into the street, (to be carried off by the
kennel there,) or into the privies, there to collect, until they are
cleared and cleaned out — which operation is usually done once or
twice a year in the better classes of houses, and only once every
two or three years in the filthier parts of the metropolis.

Those who have been accustomed to reside in London, and in
the larger provincial towns of England, are indeed surprised, and
not a little offended, by the state of things in Paris. The " fosses
d'aisance" of a private house or hotel are frequently disgusting
beyond description to more senses than one ; and the practice of
resorting to those of a more public description happily does not
well suit English notions of decorum. Every thing is so admirably

PUBLIC HYGIENE. 187

appointed with us at home, that it is only when we leave this
highly favoured, (however heavily taxed,) country, that we are
sensible of the many conveniences and comforts, which w^ are
almost unconsciously enjoying.

Our author informs us, that the expenseof emptying and cleaning
the privies in Paris has of late years greatly increased, in consequence
of the improvements which have been made in their original con-
struction. Formerly they were nothing better than holes or pits,
dug in the ground, and walled on the sides. The urine, therefore
and all other fluid refuse which was thrown down, gradually soaked
into the soil, and the worthy people of Paris did not trouble them-
selves where it went, or what became of it. But now, and for some
time past, the " fosses" are built all round, being paved on the floor
as well as walled on their sides. The advantage (?) of this im-
provement is, that there is a vast accumulation of fluid as well as
of solid filth collected during several months, until the period of
emptying and cleaning comes round. The horrible offensiveness
of this operation we need not describe. The filth is carted away
to the great metropolitan laystalls at Montfaucon and Bondy, and
there piled up in vast heaps, to undergo certain changes of fermen-
tation and desiccation, before it is sold as manure to the farmers,
or until it is exported to the provinces or to the French West India
islands.

All this appears to the English reader most incomprehensibly
disgusting. But, " what," says our author, "is Paris to do with
this enormous mass of ordure ? The construction of our houses
does not admit of its being carried away by the sewers ; and more-
over, not only should our agriculture suffer from the want of a most
profitable manure, if this were done, but the Parisians would be
shocked also, were they to suppose that the waters of the Seine,
(from which until very recently all the supply of the metropolis is
derived,) were contaminated with the contents of the fosses."

Various expedients have been proposed at different times to obvi-
ate, as far as possible, the stench and loathsomeness of the closets.
The nature of almost all these experiments has been, to endeavour
first to separate the urine and other fluids from the solid contents,
and then to remove the former either by pumping it ofl", or by with-
drawing it in some other manner.

By far however the best method is that proposed by M. Cazenave
in 1818, and which consists in the adoption of moveable closets.
Strange to say, this method has never met with encouragement from
municipal authorities, although the advantages, not only in respect
of superior cleanliness, but also of diminished expense, are very
obvious. M. Duchatelet very properly says, that no privy, however
well and compactly constructed, can prevent the oozing of the water
through its floor and walls. If such be the case, there must neces-
sarily be a permanent focus of foul exhalation in every dwelling ;
and when, says he, we consider the numerous other agents all tending
to render the abodes of the poor unhealthy, can we be surprised
that low putrid fevers are so prevalent in Paris ? Besides this

188 PUBLIC HYGIENE.

consideration, there are others which deserve to be noticed. It is
well known that there are numerous wells in different parts of Paris,
and that many of the inhabitants derive all their supply of water
from these. Now not a few of them are situated in those very
neighbourhoods, where the "fosses" are the worst constructed, and
the least attended to. The urine, therefore, permeating the soil,
must necessarily contaminate the springs, from which the wells are
fed. If there was occasion for further argument, we might allude to
the melancholy circumstances, that scarcely a season passes over
without some accident to the scavengers employed in the disgusting
duties of their calling. If we take up the Annales d'Hygiene,
almost every number contains some lamentable instance or another,
either of death from asphyxia to these men, or of the horrid crime
of infanticide, where the child has been concealed in the privy.
These accidents could not occur, if the system of moveable " fosses"
was generally adopted.

But it is especially in reference to the benefit which agriculture
might receive, that our author strongly recommends the adoption of
these contrivances. "Not only," says he, "would none of the
solid matter be lost, but the mass of it would be very notably
increased. Putrefaction and fermentation cause a very considerable
portion to be dissipated ; and moreover we are quite certain that it
is less rich as a manure in its stale, than in its recent state."

It will naturally occur to our readers to inquire, what does M.
Duchatelet recommend to be done with the fluid contents of the
" fosses," The common practice hitherto has been, to cart it away
along with the fseces, in immense casks, to the laystalls at Mont-
faucon and Bondy — there to be employed in the manufacture of
ammonia, &c., and the refuse to be afterwards carried off by the large
sewers into the Seine. Before detailing his own proposal, our author
enters upon a minute and circumstantial inquiry, whether the waters
of the Seine would be contaminated, if all the urine of the metropolis
was discharged directly into its channel. Objections have often
been made, even by able men, to this plan ; and the French
government has allowed itself to be influenced by these objections,
in many of their municipal regulations. But it appears to have
been forgotten all the time, that the sewers disgorge their contents
into the river, and that many of these, as that of Montfaugon and
Amelot, communicate with it above Paris. Where is the difference
in point of salubrity, between the conveying of the urine and other
offensive fluids directly into the Seine, and the removing of it first
to one large depositary, before it is carried off into the river by the
sewer in the neighbourhood ? M. Duchatelet, however, not satis-
fied with giving this most satisfactory reply, proceeds to show that
thedreadof contaminating the waters of the Seine is utterly groundless.
He appeals to an admirable report of M.M. Fourcroy and Hall6,
who have clearly proved, that the relative proportion of the fluids
discharged daily into the river, with the actual amount of its mass,
is so small and inconsiderable, that they can have no appreciable
effect in vitiating it for almost any purposes, domestic or economical.

PUBLIC HYGIENE. 1S9

He calculates that the annual quantity of matters from the " fosses
d'aisance" in the metropolis amounts to about 103,000 cube metres.
One fourth of this may be supposed to consist of fseculent contents ;
and the remaining three fourths, or 77,100 cube metres, to be fluid.
We may therefore estimate the daily quantity at 211 cube metres.

Now the average volume of the water of the Seine, even in a dry
season, may be taken at 30,710 times larger than this quantity — 211
cube metres.

During the winter and Spring months, and after any continued
fall of rain, the preponderance is vastly more considerable. If we
take the medium quantity of water in the Seine, as it passes through
Paris, the flow may be estimated at 255 metres in the second ; — a
quantity, which exceeds that discharged into it from the sewers by
at least a million times.

The conclusion from all these calculations is, that the fluid contents
of the "fosses" might be discharged directly into the Seine, without
any danger of contaminating its waters.

Having resolved this point, M. Duchatelet proceeds to inquire,
what would be the most convenient and appropriate method of con-
veying these fluid contents to the river.

Our readers already know that this cannot be effected very easily
in Paris by means of the sewers, in consequence of the v^^ant of pri-
vate drains communicating with them. It is to be hoped that the
Parisians will at length be convinced of the utility, or, we should
rather say, the absolute necessity of these ; and that the present
method of carting away all the fluid as well as the solid contents of the
"•' fosses" will be gradually abolished. Many a year however must
pass over before this can be done ; and until that fortunate time ar-
rives, M. Duchatelet suggests that, if the moveable "fosses" were
universally adopted, and emptied daily of their fluid contents, these
might be advantageously got rid of, by discharging them into the
kennels in the middle of the streets — at least in those places of the
metropolis where there is a sufiicient supply of pure water to keep
up a constant current along these kennels.

This proposal may, on first consideration, appear very objection-
able ; but our indefatigable author assures his readers, that he has
quite satisfied himself that theaddition to urineof from four tosix times
its quantity of water will deprive it of all its offensive smell. Since
the opening of the Canal d'Ourcq (one of the great works of Paris
recently completed, and one, by means of which every part may be
abundantly supplied with water), there can be no scarcity of water ;
and the proposal therefore of M. Duchatelet, with the view of induc-
ing every householder to become a subscriber to this great under-
taking, is " qu'il sera dorenavant permis aux particuliers d'envoyer
sur la voie publique les urines, et les produits liquides des fosses
d'aisance ; mais seulement lorsque I'eau de I'Ourcq arrivera chez
eux, et lorsque son ecoulement pourra se faire, sur cette voie pub-
lique, en assez grande abonda.nce pour que ces matieres soient saos
odeur fetide."

18*

190 PUBLIC HYGIENE.

Before quitting the subject of the " fosses d'aisance" M. Ducha-
telet offers a few remarks, as to the best method of employing the
solid contents. For the purpose of destroying their effluvia and of
preventing their fermentation, he suggests that a quantity of animal
charcoal, or, in lieu of this, which of late years has become very
valuable and therefore very expensive, of calcined peat, or of the
refuse of tan yards, &c. be mixed with the fseculent matters, before
and after their removal from houses.

By the adoption of such simple means, much of the inconvenience
and offensiveness of the present processes might be avoided ; and the
heaps of ordure accumulated in the laystalls, which in the present
day are so disgusting, would be comparatively much less putrescent,
and therefore better fitted for transportation as manure, either to the
provinces, or to the colonies abroad.*

" In conclusion," says our author, " the changes now proposed in
the construction and regulation of the ' fosses d'aisance' are of such
high importance, and the results, which might be obtained from their
adoption, are so useful and so extensive, that they would suffice to
distinguish and to recommend to the gratitude of future ages the names
of those administrators, who may happily enforce them. This glory
is reserved for the present two Prefects of the department of the
Seine, and for the Municipal Council of Paris ! !" ♦

So much for the " fosses d'aisance" of Paris. But before quitting
the subject, it may be proper to allude to M. Duchatelet's 14th
Memoir, which is entitled " Researches to Discover the Cause and
the Nature of the Alarming Accidents, which occurred at Sea
on board a Vessel loaded \N\i\\ poudrette.^' The vessel it seems
sailed from Havre with a cargo of this most disgusting manure, and
was bound for Guadaloupe. In the course of two or three weeks
after leaving port, a scorbutic fever appeared among the crew. One
half of them died, and the remainder, when they reached their des-
tination, were miserably ill. Our author was appointed by the
Marine to investigate into the particulars of the case, when the vessel
returned to France.

It is not our intention to follow him through the details of the
report, which he drew up on the occasion. Suffice it to say, that
he came to the conclusion that \\\e poudrette had been shipped when
it was too wet ; that it ought to have been better dried ; and he very
properly suggests that a quantity of lime should be mixed with it,
before it is taken on board any vessel. The effect of the lime is to
absorb moisture and to counteract putrefaction and fermentation :
besides it is well known to be a useful manure itself.

If we were to give an opinion on the subject, we should say
that no vessel should be allowed to carry such a putrid cargo —
certainly not when bound to a tropical climate. Is it not strange

* This sort of manure to which the French give the name of "poudrette,"
seems to be an article of very considerable commercial importance in France.

PUBLIC HYGIENE. 191

that the fertile and luxuriant soil of the West Indies should require
dung, as manure, from Europe ?

The sixth memoir on the sewers of Paris, is the most elaborate
one of the collection. The author very justly remarks, that the
position of the French metropolis, lying as it does in a nearly hori-
zontal valley, renders the necessity of a proper system of drainage
the more imperative, while it adds greatly to the difficulty of eflfect-
ing this most important object. Much, he admits has been done ;
that much remains to be accomplished, before Paris can be called a
clean, or well appointed city. If there were a few more such zealous
labourers as our author, the good work would be quickly advanced.
Multitudes are hourly traversing the streets of the gay metropolis,
engaged in their business or their pleasure, without for one moment
considering, or perhaps without being at all aware of, the fact, that
they are passing over subterranean and therefore unseen, but most
important and necessary structures, without which the existence of
the health of the inhabitants would be speedily compromised, and
the streets rendered almost impassable. They do not remember,
that a number of their fellow-citizens voluntarily condemn them-
selves to pass their lives in subterranean canals, exposed to all sorts
of loathsome offensiveness, and doomed not unfrequently to perish
while engaged in their revolting occupations. And yet, without
the assistance of these men, a great part of Paris would become
quite uninhabitable, and must necessarily relapse into the state of
an unhealthy marsh ; such as it was three or four centuries ago. It
is well known that the site of the Louvre, of the Tuileries and its
gardens, and of the Champs Elysees, was formerly a swampy morass.
The ground is very low, and used to be generally overflowed by
the river during the Winter.

M. Duchatelet commences his memoir by alluding to the cloacae
of ancient Rome, which are always viewed among the mightiest
monuments of its greatness. Not satisfied with committing the
superintendence of these important structures to the care of the first
men of the state, the people of Rome invoked the protection and
assistance of certain divinities to preserve them. They had their
god, Sterquilinus, and their goddesses, Cloacina and Mephitina,
under whose special patronage all the public cloacae were believed
to be.

Such was the consequence attached by the Romans to those great
works. M. Duchatelet gives a very good and instructive account
of them ; and then proceeds to examine the state of the sewers in his
own metropolis. — Certainly no one was better qualified than he to
reprove and to instruct his countrymen on this subject. He had
devoted, as we have already said, several years of his active life to
the investigation of it. He had not only traversed every consider-
able sewer in Paris, and had conversed with all who knew any thing
of them, from the highest member of the Academy, to the lowest
of the workm.en, but he had even repeatedly assisted the latter in
their occupations.

192 PUBLIC HYGIENE.

" J'ai surmonte sans hesiter la repugnance et les dangers insepar-
ables de pareilles recherches ; j'y ai sacrifi6 mon temps, et mon
argent, et ma peine ; je ne puis dire les demarches que j'ai faites, les
fatigues que j'ai eprouv6es, et les contrarietes de toute espece qu'il
m'a fallu endurer." Such was the discipline which our excellent
author submitted to.

He first gives an historical sketch of the sewerage of Paris, from
the earliest period down to the present time. The perusal of this
sketch will well repay the readers who may take any interest in
the past and present state of the French metropolis, and more
especially those who at the same time are fond of geological researches,
respecting what has been called, by Cuvier and Brogniard, the basin
of Paris ; but it is impossible for us to do more than merely to
allude to it.

In another part of this article, we have explained in what manner
the contents of the "fosses d'aisance" are got rid of. They are not
discharged into the sewers, but are conveyed away to the great de-
positaries at Montfaugon and Bondy.

In this respect, the sewers of Paris are greatly inferior in point
of utility, as well as of cleanliness and general management, to those
of ancient Rome, and of London and other British towns. Not
only are their dimensions much smaller, but their course also is
uneven and irregular, and henee the current through them is slow
and apt to stagnate.

It is to these causes that we are to attribute the numerous accidents
which occur every year to the workmen employed in cleansing
the sewers of Paris. Such casualties are never heard of in London ;
whereas in Paris they are very frequent.

The Parisian sewers, every now and then, become obstructed
from the deposit and accumulation of their solid contents ; a large
quantity of carburetted and sulphuretted hydrogen gasses is evolved,
and the workmen, who are exposed to the effluvia, are apt to be
asphj'xiated.

Another topic, which has given rise to repeated discussion among
men of science, as well as among the municipal authorities of Paris,
is the question, how far the waters of the Seine, from which almost
the whole supply of the metropolis is derived, are apt to be con-
taminated by the discharged contents of the sewers.

Numerous experiments have been performed to ascertain, whether
there is any appreciable difference in the water of the river above
the city (say at the Bridge of Auslerlitz), from that lower down (at
the Bridge of Jena). The result of all these experiments has been,
to show that chemical analysis does not discover any difference.
Hence it has been concluded, that the contents of the various sewers,
as well as of the filthy streams, such as the Bievre, which flow into
the Seine, are quite neutralized by the comparatively enormous
mass of water in the river.

This may be the case, says our author, in Winter, and after heavy
falls of rain ; but during the Summer months, especially when the

PUBLIC HYGIENE. I93

season has been very dry, he has himself repeatedly observed, that
the water of the river has been foul and discoloured, even as low-
down as Sevres, from the foreign matters discharged into its channel
where it flows through Paris. The left or South side of the river
is always infected in a greater degree, and for a greater length of
time, than the opposite side — owing to the contaminating stream of
the Bievre, on the banks of which most of the ofifensive manufac-
tories are situated. Perhaps, says he, at no part of its course, is the
Seine so muddy and filthy, as where it passes under the Hotel Dieu
Hospital.

M. Duchatelet next proceeds to inquire what influence the sewers
have on the health of workmen, employed in keeping them in repair.
He first alludes to the effects which they produced upon himself.
The usual symptoms, which he first experienced, were headache,
and a certain degree of stupor, dryness of the throat, thirst, loss of
appetite, and sometimes slight dyspnoea ; but all these inconve-
niences speedily passed away, after he remained some time in the
sewer. With respect to the general appearance and health of the
regular workmen, he tells us that they are almost all thin, and rather
meagre ; their complexion is generally pale and earthy ; the lines
of the face are deeply marked ;* the abdomen is usually much re-
tracted ; — yet, on the whole, the health of these people is " parfaite
et fort rarement derangee. Their lives, too, do not seem to be at all
shortened by their apparently most unhealthy occupation. Many
of them suffer from lumbago and sciatica, — in consequence, probably,
of the wet to which they are exposed, and also of the bent position
which they are so often obliged to maintain for a length of time.
They are, he assures us, very rarely the subjects of cutaneous dis-
ease, or of any of those maladies which have been called "pu-
trid !" But, from numerous observations and inquiries, M. Du-
chatelet is satisfied that all venereal complaints are greatly agra-
vated in the workmen, if they continue their occupations. Indeed,
it has been very often remarked, that an impure atmosphere, of any
description, is exceedingly unfavourable to the recovery of syphilitic
patients : the disease generally becomes worse, and the only satis-
factory method of effecting a cure is removal into the wholesome air
of the country.

The same observation was made, forty years ago, by Parmentier
and others, in their memoir on the health of the " vidangeurs," or
those employed in cleaning the " fosses."

The late distinguished M. Halle, who probably did more for the
hygiene of Paris than any single individual, confirms the truth of
the statement, that syphilitic disease is always exceedingly obstinate
and severe in these men.

But of all the dangers, to which the workmen are exposed, none

* These men seldom exhibited that bleared appearance of the eyes, so commonly
observed in the regular scavengers, such as are employed in emptying the " fosses
d'aisance." M. Duchatelet attributes this affection to the ammoniacal gas,
evolved from putrefying fascal matter. Now this gas does not exist, or only in
minute proportion, in the sewers.

194 PUBLIC HYGIENE.

is so alarming as that of asphyxia from the air becoming vitiated
with azote, sulphuretted hydrogen, and other irrespirable gases.
The symptoms, accompanying the attack of asphyxia, vary somewhat
according to the nature of the gas which has caused it. If it has
been the ammoniacal sulphuretted hydrogen, the person is seized
very suddenly ; he becomes quite insensible in the course of a min-
nute or so, and death is usually preceded by convulsions of the limbs.
On the other hand the attack is much more slow and gradual, when
the asphyxia has been induced by azote : the breathing gradually
becomes more and more embarrassed ; vertigo and confusion come
on ; there are no convulsions ; and the person is slowly suffocated.
From what M, Duchatelet has observed, azote is the gas which is
most frequently and most abundantly evolved in infected sewers.*
The presence, however, of the sulphuretted and carburetted hydro-
gen gases, must add greatly to the pernicious effects of the azote.

In 1826, one of the chief sewers in Paris, that of Amelot, became
obstructed, in consequence, we believe, of its having been neglected •
for a length of time. Various attem.pts were made to clear it out ;
but none of these attempts had succeeded, and indeed most of the
workmen, who had been employed, had suffered from more or less
complete asphyxia, and some of them had lost their lives. The
sewer was therefore left to itself, and became an insufferable nuis-
ance to all the district ^through which it passed. In course of time
it was completely stopped up, and then the contents flowed back
upon the streets, and even into the courts of many houses in these
streets. To add to the difficulties to be overcome, we ought to state
that a new sewer had, a short time previously, been made to termi-
nate in the obstructed one, and that all the blood, garbage, &c. from
one of the chief " abattoirs" of the metropolis, as well as the water of
many thousand sulphureous baths used at the Hopital St. Louis, were
discharged into the former. A commission, consisting of some of
the most distinguished engineers and chemists, was appointed by
the Prefect of the Seine to superintend the operation necessarry for
the " curage et I'assainissement" of these sewers. Our author was
the secretary and reporter of this commission.

The workmen began their unpleasant operations at the mouth of
the sewer, where it terminates in the Seine opposite to the " He
Louviers." They were engaged for upwards of six months in this

* The results of two analyses are these : —

In one, the proportion of azote was 94 ;

of oxygen 2;

of carbonic acid, &c. gas . . 4 ;

In the other the proportion of azote was . . . . 89;
of oxygen . . . . 6 ;

of carbonic acid, &c. gas . 5;

M. Duchatelet has appended a table of twenty-one analyses of the air, taken
from infected sewers. In every one of these, the proportion of azote was found
to be greatly increased, and that of oxygen to be correspondingly diminished.
We recommend physicians and chemists to examine the particulars of this table
for themselves.

PUBLIC HYGIENE. I95

offensive and dangerous duty ; but, in consequence of the admirable
arrangements made, and the hygienic precautions which were taken,
not a life was lost ; although several of the workmen were at differ-
ent times, partially asphyxiated. By bringing them, however, at
once into the open cool air, and exhibiting stimulants, most of them
were quickly restored. In one case, after respiration was freely
excited, a universal shivering, followed by convulsions of the limbs,
came on : to these symptoms succeeded delirium, and then absolute
mania ; the patient roared and screamed aloud, tossed himself in all
directions, and appeared to be quite insensible of those about him.
After the operation of an emetic, his consciousness gradually re-
turned, and in the course of a few days he had quite regained his
former health.

Another man was brought to the surface insensible, pale, and
motionless; the limbs being quite relaxed and the respiration sus-
pended. By sprinkling cold water on the face, the breathing was
restored ; and then a few spoonfulls of an setheral mixture brought
back his consciousness and power of motion.

The directions, which M. Duchatelet gives for the treatment of
persons asphyxiated by foul air, deserve to be shortly noticed. The
person ought to be immediately brought into the open air, stripped
of all his clothing, stretched out on the ground, with the head slightly
thrown back ; cold water should then be dashed smartly on the face
and chest ; vinegar or volatile alcali should be applied to, or injected
into the nostrils, and the nostrils and throat should be tickled with
a feather. Friction on the surface is also very useful.'

If these means do not quickly succeed, then artificial respiration
must be induced. M. Duchatelet has never seen any good, but
sometimes serious mischief, from letting blood in asphyxia from
breathing a foul air. He therefore, as a general rule, condemns the
practice, until the patient has recovered from the immediate effects
of the attack. This caution is the more necessary to be attended to,
as medical men are far too apt to bleed indiscriminately in most
cases of suspended animation — and we may add, of injuries of the
head, and apoplexy. Whenever the act of breathing commences,
the great difficulty is overcome ; for, when once begun it is easy to
promote it by stimulants to the nostrils, by the feather introduced
into the throat, and by tickling the soles of the feet. In the after-
treatment of these cases, it is frequently necessary to apply leeches
to the temples, or even to bleed from the arm, and to administer
derivative medicines, to counteract the cerebral congestion.

We have already mentioned that some of the workmen suffered
repeatedly from ophthalmia. This affection was transitory, if treated
at once with astringent stimulating collyria. Sedative and emollient
applications were of no benefit.

The attack of colic, which in some cases quite resembled in
severity the worst form of colica pictonum, yielded generally to
antispasmodic purgatives.

Before quitting this subject, we shall briefly allude to some of the

196 PUBLIC HYGIENE.

most approved means to be employed by those who venture into
places v^^here the air is much vitiated. The first thing to be con-
sidered is, whether it be possible to establish a current of atmospheric
air through the place, by establishing a second opening in an oppo-
site direction from that where the first is situated. If this can be
done, the most ready and effectual mode of causing a free circulation
of air is, to place a brazier of live coals between the two openings.

After ventilation, perhaps no means are more powerful in coun-
teracting the deleterious agency of foul air, than chlorine and the
chlorurets. The chlorine itself — obtained from a mixture of the
oxide of manganese and of muriatic acid — is, for general purposes,
too strong and suffocating to be employed while the workmen are
in the sewer ; but this objection is obviated by having recourse to
its use, an hour or so before the men go to work. The chloruret
of lime, however, on the whole is to be preferred. It yields a slow
and very steady supply of chlorine ; never too free to incommode
the breathing, and yet active enough to purify the surrounding air.
Another advantage which it possesses is, that it may be used either
in a dry or fluid form. One of the most convenient modes of using
it by the sewermen and others, is to sprinkle a quantity of the dry
powder on a heap of straw : it should be renewed four or five times
in the course of the day. Another very good plan is to take a wide
mouthed bottle, and fill it with tow, on which the dry chloruret has
been sprinkled. This bottle should be hung round the workmen's
neck. Besides these precautions, it is useful to wash the face and
hands repeatedly with the solution, and to throw a quantity of it on
the offensive materials which the men are working at.

Masks of various forms, and other similar contrivancies have been
suggested, with the view of enabling persons to pass through, and
to remain in places where the air is more or less vitiated.

During the plague which raged at Marseilles in 1720, the physi-
cians and other attendants on the sick were in the habit of using
masks, which covered completely the head, and were provided with
eye-holes,and with a long appendage opposite the mouth and nostrils,
and anointed on its inner surface with various balsamic substances.

The simple expedient of tying a piece of sponge, or folded linen
well wetted with vinegar, over the mouth and nostrils may often
be used with much advantage. M. Fosse, who has paid much
attention to the subject now under consideration, informs us that
with this simple means he has been enabled to enter the most
infected places, and to continue in them for 10 or 15 minutes at a
time without experiencing any inconvenience. The fluid, with
which the sponge is wetted, should be different according to the
nature of the deleterious emanations. Thus, when M. Fosse went
into a chamber filled with the fumes of sulphur, he found that a
solution of potash was most useful. On other occasions, when he
was exposed to the abominable effluvia of sewers and privies, vinegar
or a solution of the chloruret of lime was preferred. Lime water
is probably the best preservative against carbonic acid fumes. Pure

PUBLIC HYGIENE. I97

water will suffice to purify the air from matters which are merely
diffused mechanically through it, and to condense the vapours of
metallic substances, as of mercury and arsenic.

To enable persons to remain for a greater length of time in an
irrespirable atmosphere, it is necessary to have recourse to some
means, by which a communication may be established either with
the external air, or with a reservoir containing it. Such is the
principle, it is well known, by which the men who go down in
diving-bells are enabled to continue under the surface of the water
for several hours at a time. On one occasion, at Bourdeaux, M.
Duchatelet saw the workmen remain for nearly six hours continu-
ously under water.

We may here allude to a very ingenious contrivance, proposed
some years ago by an English workman of the name of Robert, to
enable persons to enter into the rooms of a house on fire, and to
remain in the suffocating atmosphere for a considerable length of
time. The principle, on which this contrivance rests, is that the
air in rooms filled with smoke, is always much less vitiated near
the floor than towards the ceiling. The apparatus consists of a
mask, provided with eye-holes, which is put over the head, and
secured with a tape round the neck, so as to prevent the admission
of the surrounding air to the mouth and nostrils. A leather tube,
four or five feet long, proceeds from the mouth-pieces to which it is
secured, and this hangs down to near the ancles ; through it the per-
son breathes. The open and inferior end of it is lined with flannel
or with thin pieces of sponge, which have been previously well
wetted either with plain water, or with vinegar and water. The
first experiments were performed in public at Manchester, in 1825.
Robert and another workman, provided with their apparatus, went
into a room in which a quantity of cotton had been burned, and
which was quite full of smoky vapour ; they remained in it for
twenty minutes. On another occasion a quantity of moist straw,
chips of wood, sulphur, and resin, was set fire to in the middle of
a room, and the windows and door tightly closed, so that the room
was quickly filled with the most suffocating smoke. Robert remained
in it for upwards of half an hour. He was indeed considerably
exhausted when he came out; but this exhaustion seemed to be
owing rather to the highheat of the room, than toanyembarrassmentof
the respiration. Numerous other experiments were performed with
the apparatus both in this country and in France ; and M. Ducha-
telet informs us that it has been (with certain modifications) so
much approved of in Paris, that every body of firemen is provided
with it. The chief objection to it — but one which may be very
easily remedied — is, that the expired air is not got rid of, but enters
the tube to be again inspired. If it was provided with a double,
instead of a single, tube — the one for inspiration, and the other for
expiration — the apparatus would be much more efficient. The
reader will find a number of useful diagrams and descriptions of
different instruments in M. Duchatelet's work.
m 19

198 PUBLIC HYGIENE.

Here we must stop in our analytic review. Happy we should
have been, had the author been spared to meet the reward of praise
and of profit which his labours have so richly merited. But
naturally feeble, and of a delicate constitution, the powers of his
body were unequal to support the energies of his too active mind,

" A fiery soul which, working out its way,
Fretted the puny body to decay,
And o'er-informed the tenement of clay."

His literary and scientific works will long remain a monument of
his unwearied and most meritorious exertions.

EXPERIMENTS

BRAIN, SPINAL MARROW, AND NERVES.

*Among the physiologists who have endeavoured to investigate
the functions of the brain and nervous system in modern times,
Professor Mayer places our distinguished countryman Sir C. Bell
foremost on the list ; adding the names of Rolando, Bellingeri,
Magendie, and Flourans. The experiments of Flourans are some of
the most important on this subject, but the great objection to them is
the extensive injury which was unavoidably produced upon the brain,
its nerves, and vessels, during these experiments; so that the precise
effects upon the brain were probably more or less modified by the
effects of the operations. Professor Mayer's object has been to
repeat the experiments on a more simple plan ; to avoid opening
the cavity of the cranium, wounding the vessels, the severe hemor-.
rhage, and exposure of the wounded parts to the atmospheric air ;
and thus to make the result more simple and certain. He has en-
deavoured to determine how far the influence which the activity of
the brain exerts upon the organic system is disturbed, where, without
having undergone any injury, its supply of blood, which we must
look upon as the chief source of its vitality and activity, has been
partly or wholly cut off.

We may effect this object in two ways : viz. by tying the arteries
which supply the brain, and by injecting some foreign fluid into
these vessels. With regard to the first method, this chiefly refers
to putting a ligature upon the two carotids, because tying the verte-
bral arteries at the same time is not only almost impossible to effect,
but, as we shall also find, is instantly fatak On the other hand,
putting a ligature upon both carotids, and also upon one subclavian,
may be effected, as will be seen shortly.

The experiments of tying both carotids, besides their physiological
value, are interesting to the medical practitioner, because cases
might occur where it was necessary to undertake this operation in
the human subject : it is therefore highly desirable to be previously
acquainted with its effects on animals. This applies equally to the
operation of tying one carotid.

"On a former occasion," says Professor Mayer, "I have called
the attention of the surgical part of the profession to a consequence

* From the British and Foreign Medical Review.

200 EXPERIMENTS ON THE

of tying the carotid, as regards morbid action in the eye.* These
views have been recently confirmed by a new fact, viz. that in the
operation for tying the carotid of a man, which was performed by
Professor Biinger at Marburg, the eye of the same side suffered
considerably.

It will be impossible to give a detailed account of these experi-
ments ; we shall therefore content ourselves with presenting to our
readers a short summary, which the author himself has given at the
end of the physiological part.

Expermient 1. One carotidt being tied in a rabbit, produced
no peculiar symptom.

Ex2)eriment 2. Both carotids being tied in a dog, the following
symptoms were observed : The action of the heart diminished some-
what; the respiration sunk from forty-two to twenty-eight; weakness
of the eyes, sopor, trembling ; the body drawn to one side. The
animal recovered in six days.

Expe7'ime7it 3. Tying both carotids in a rabbit produced no
peculiar change.

Experiment 4. The same operation on a dog produced sopor,
weakness in the eyes, and diminished number of respirations in a
minute. In the course of four days the animal recovered.

Experiment 5. The same operation in a pigeon produced a
very considerable effect : viz. debility of the eyes, vertigo, trembling
of the head, inability to stand erect ; respiration sinking from 105
to twenty-two in the minute ; the temperature diminished 4° 5'
Fahr. : the action of the heart experienced but little change. The
animal died on the fourth day, convulsed.

Experiment 6. Tying both carotids in a rabbit produced trem-
bling of the head,f8ecal vomiting, convulsions, and death in fourteen
hours.

Experiment 7. The same experiment made on a horse was
followed by very violent symptoms : weakness of the eyes, vertigo,
collapse as if struck by lightning, incapacity of swallowing, violent
madness, convulsions, and death in fifty-eight minutes.

Experiment 8 produced the following symptoms in a rabbit :
insensibility of parts in opposite directions, viz. the right ear and
left eye ; expression of alarm ; drawing the head to one side ; diminu-
tion of the heart's action ; increased rapidity of respiration. Re-
covery on the third day.

Experiment 9. Tying the two carotids and left par vagum
produced the following effects: The head became lifeless, especially
upon the left side ; the left eye insensible ; the animal fell on the
left side ; convulsions, trismus, and tetanus followed ; the respiration
became slow and rattling ; the heart's action weak, and the temper-
ature fell 15°75' Fahr. General paralysis, and death in six hours

* Journ. fiir Chirurgie und Augenheilkunde, von Dr. v. Graefe, &c. 10 band,
3 heft.
"J" By carotid is understood throughout the Carotis communis.

BRAIN, SPINAL MARROW, AND NERVES. 201

after the operation. On examination after death, extravasations of
blood were found in the lungs and stomach, the lining membrane
of which was corroded.

Experiment 10. Both carotids of a rabbit were tied ; a series
of remarkable symptoms were the result. The paralysis was dis-
tinctly crucial : there was insensibility of the eye and ear, (the left
eye became insensible from the beginning, as also the right ear ;
whereas, the right eye and left ear continued sensible for some
time ;) tetanus and trismus ; incapacity of swallowing, food returning
from the oesophagus ; the heart's action but little diminished, whereas
the number of respirations fell to sixteen ; the temperature sank
27° Fahr. ; entire loss of animal heat, and death from loss of sensation
and irritability on the fifth day. After death, an unusual quantity
of pure gastric juice was found in the stomach. In both eyes an
inflammatory membrane had formed on the anterior surface of the
iris, closing the pupil.

Experiment 11. The symptoms were as follows. Distinct
crucial affection of the ear and eye ; both eyes afterwards became
insensible ; tetanus and trismus ; the head twisted to one side ;
chorea ; pulsations of the heart reduced to ninety, respiration to
twenty; the temperature fell 23° 5' Fahr. General paralysis, and
death in nine hours and a half Extravasations of blood were found
in the stomach, the lining membrane of which was corroded.

Experiment 12. Both carotids and the right subclavian artery
of a goat being tied, diminished the respiration and action of the
heart ; it produced affection of the eyes, vertigo, tottering with the
head, inability to keep itself on its legs, tetanus, and death in four
days.

Experiment 13. Injuring the cerebellum of a rabbit, by passing
an iron wire through it, and, five days after this, tying the carotids,
produced similar symptoms as in the eleventh experiment : the
animal died on the eighth day. An inflammatory membrana pupil-
laris was found in the eye.

Experiment 14. Injuring the cerebellum of a rabbit produced
no peculiar symptom ; whereas, tying the carotids seven days after,
(in doing which, the right par vagum and sympathetic were in-
cluded,) produced similar results as in the tenth and eleventh
experiments: viz. the right eye was paralyzed, the cornea ulcerated,
and, on dissection after death, an effusion of lymph was found on
the anterior surface of the iris. The animal died on the twenty-
first day.

Experiment 15. The two carotids having been tied in a rabbit,
the symptoms already described appeared; of which, the faecal
vomiting especially vi^as very severe. An iron pin was passed into
the brain on the sixth day : the animal appeared blind, ran against
every thing, and died on the eighth day.

Experiment 16. Tying the carotid and subclavian arteries in a
rabbit produced death in the space of a minute. It was very re-

19*

202 EXPERIMENTS ON THE

marlrable, that the heart continued to beat actively six minutes
after. Even forty minutes after death, when the animal had become
stiff for full ten minutes, the heart still beat eleven times in the
minute.

Experiment 17. The same operation instantly destroyed a
pigeon.

Experiment 18. Tying the carotids in a marmot, which was in
its hybernating sleep, produced complete rigidity and death.

Experiments of injecting a foreign Fluid into the Carotids.

Experiment 19. The injection of a little quicksilver into the
carotid of a rabbit produced violent sufi'ering, vertigo, twisting of
the head, insensibility of the eyes, (first of one, then of the other
side,) diminished action of the heart and respiration. The animal
died in twenty-two minutes.

Experiment 20, Under the same circumstance, lifelessness of
the head and body, tetanus, and death in four minutes.

Experiment 21. The symptoms were, diminution of the heart's
action, of the respiration and animal heat ; hemiplegia, and crucial
paralysis of the head, eyes, and ears ; trismus ; refusal to take food ;
incapacity of swallowing ; faecal vomiting ; rigidity, and death on
the fourth day. On examining the body, the lining membrane of
the stomach was found corroded, and an inflammatory exudation in
the eye. The similarity of the phenomena with those observed after
tying the carotids is remarkable : (see Exp. 10.)

Experiment 22. The paralysis of the head and eye was still
more distinct in this instance ; the cornea of the left eye ulcerated.
Death, on the eighteenth day, resulted from diminution of temper-
ature, rigidity, and want of nourishment.

Experiment 23. A small quantity of common injecting wax
was tfirown into the carotid of a ram. It produced sudden loss of
sensibility, of motion, and life, in the head, which spread gradually
over the whole body. The respiration stopped, as if the animal
seemed to forget the necessity of its continuance. The heart's
motion continued active, as if the remaining powers of life had con-
centrated themselves upon it. The animal died in twelve minutes.

Experiment 24. The same phenomena were produced in a goat,
and death in eight minutes.

From these experiments Dr. Mayer draws the following con-
clusions :

1st. That a healthy state of the cerebral activity is the necessary
condition of life : in other words, the encephalum (viz. the brain,
cerebellum, and medulla oblongata,) is the peculiar source of vital
power, — the ybw-s vitalis.

2d. The medulla spinalis, of itself, is not sufficient for the con-
tinuance of life, as its own lif'e depends upon the vital energy of the
encephalum. This inference is deduced especially from the results
of the Experiments 23 and 24.

BRAIN, SPINAL MARROW, AND NERVES. 203

3d. The vertigo and inability of preserving the upright posture is
also a result of impeded cerebral activity. We are scarcely justified
in attributing these effects to an injured state of the functions of the
cerebellum, because, even in the experiments where the vertebral
arteries are tied, the cerebellum receives a sufficient supply of blood.

4th. These experiments, moreover, tend to show that the brain
directs and guides the vital functions. The cause or principle of
the vital functions (viz. the circulation, respiration, nutrition, animal
heat, &c.) is not in the encephalum, but the impulse to exert these
functions of vegetative life emanate from it ; and they cease when
the encephalum sinks into inaction.

The necessity (we might almost say the recollection) of the vital
functions stops the instant the vital activity of the encephalum is
interrupted : the animal suddenly ceases to breathe, or merely
breathes slightly, and always slower; it holds the food in its mouth,
forgets to swallow it, or lets it fall out again. The stomach retains
some contractile power, but it is an antiperistaltic motion, producing
faecal vomiting. Where the destruction of the activity of the en-
cephalum has been gradual, general insensibility comes on, and the
animal dies, from loss of its animal heat, from hunger, rigidity, and
exhaustion. If we compare these experiments with those made by
Flourens, their results will be found extremely similar. The
symptoms which occur in the comatose stage of typhus come under
the same head : patients in this state die through insensibility to
the vital functions, from paralysis of the encephalum, if they be not
continually roused from their sopor, and stimulated by sinapisms, &c.

The physiological researches, especially during the last thirty
years, both in this country and the continent, have satisfactorily
proved that most, if not all, of the agents which exert such destruc-
tive energies on the nervous system do it through the medium of
the circulation : this has been shown by the experiments of Christison
and Coindet, of Brodie, Emmert, Viborg, and many others. Those
of Sir B. Brodie on the action of the woorara poison are well known.
Emmert showed this to be the case in a still more striking manner,
by amputating the leg of an animal, and leaving it connected with
the body only by means of the nerves : poisonous substances intro-
duced into the foot produced no effects, not even when applied to
the trunk of the nerve ; and Viborg even applied one drachm of
concentrated prussic acid to the brain of a horse which had been
exposed by trepanning, without producing any effect. The experi-
ments of Dupuy* on the contamination of the vital current strikingly
confirm Dr. Mayer's observations. He found that injecting water,
in which muscle had been soaked for four and a half years, produced
symptoms in animals precisely similar to those of typhus; viz.
debility, loss of sight, coma, falling of the head, &c. Gaspardt also

* Injection des Matieres putrides dans la Veine Jugulaire du Cheval. Nonv.
Bibl. Med. 1823, Jan., p. 90.

f Memoire Physiologique sur le Mercure. Magendie's Journal, t. i. No. 2,
p. 165.

204 EXPERIMENTS ON THE

injected mercury (half an ounce) into the carotid of a sheep, which
produced insensibility, coma, and death in fifty minutes ; but he
does not appear to have carried the subject further in this direction,
or to have made any practical deductions from it.

"The impulse," says Professor Mayer, "andthefeeling of necessity
to keep in action the vital functions, has its seat in the encephalum.
Thus, when we reverse the experiment, and separate the head and
brain from the trunk, especially in new-born animals, we observe
symptoms of the above-mentioned impulse in the decapitated head.
The heads of newly-born puppies or kittens, when thus separated
from the body, suck the finger which is put into the mouth for ten
or fifteen minutes. Attempts at respiration are made by opening
the mouth, (a fact first noticed by Le Gallois,) and by the glottis
alternately opening and shutting."

Dr. M.'s fifth and last inference is, "that the above-mentioned
experiments tend to prove, beyond doubt, that the circulation, the
production of animal heat, and lastly nutrition and secretion, depend
on the activity of the encephalum, and they stop when it stops ;
moreover, that the impulse to the continuance of these functions
proceeds from the encephalum. It cannot be denied that a variety
of causes connected with these functions have their' seat in the
body ; but the main-spring, which sets all the^ wheels of the vital
functions in motion, and without which they stop, resides in the
encephalum."

The anatomical part of this interesting essay presents some
minute research and elaborate investigation, which can only be ap-
preciated properly by aid of the engravings with which it is illus-
trated. Our limits, and the nature of the British and Foreign
Medical Review, will prevent our taking such copious extracts as
we could have wished, and we must merely confine ourselves to a
general outline of Professor Mayer's labours.

Experiments have shown that the most vital part of the encephalum
extends from the pons Varolii along the whole medulla oblongata,
and at least as far as the second cervical nerve of the spinal marrow ;
in any part of which a wound is instantly fatal; that, as we descend
along the medulla spinalis below this point, or ascend to the brain
and cerebellum above it, the effects of injuries become gradually
less fatal and dangerous. Professor Mayer's object therefore has
been to subject this centrum vitate to a minute and rigorous ex-
amination, and he has shown it to be a rich field for observation
and discovery. It will be excusable in us to indulge in a little
national pride in translating the following passage : if we had no
other motive than that of respect for the distinguished physiologist
to whom it refers, it would be sufficient ; but we deem it no more
than fair to show how honestly and honourably the Germans ap-
preciate the labours of other nations. We give it literally.

"The importance of distinguishing between the anterior and
posterior origins of the spinal nerves, since this fact was first es-
tablished by the talented Charles Bell, has been particularly insisted

BRAIN, SPINAL MARROW, AND NERVES. 205

upon. Magendie has the merit of having fully confirmed these
facts by the test of experiment, in which he has so often displayed
the master's hand ; and Joh. Miiller has still more recently confirmed
the original views of Bell by experiments on frogs."

The results of Professor Mayer's researches on the origin of the
glosso-pharyngeal nerve, the par vagum, the hypoglossus, spinal
accessory, and first cervical nerves, is to show that, of these, the
hypoglossus, the spinal accessory, and first cervical, belong to that
class of nerves which possess the double faculty of sensation and
motion. The question is, does not this compound structure enter
more deeply into the organization of the nervous system ; or, in
other words, shall we not find evidences of it in the phrenic, and
even in the sympathetic nerves ?

"With regard to the phrenic nerve," says M. Mayer, "I am aware
of no researches in which its origin has been traced farther into
the fourth cervical nerve. Fig. 1 not only shows the manner in
which the phrenic gives off four twigs to the ganglion spinale of
the fourth cervical nerve, but is also continued by means of two
others along the anterior root of this nerve into the spinal column,
so that we may justly say that the phrenic has its origin directly
from the medulla spinalis. This is the more remarkable, because
the phrenic, with the exception of its connexion with the cardiac
nerves of the par vagum and sympathetic, is purely a muscular
nerve (going to the diaphragm). If we examine the sympathetic,
we shall find that Soemmering has distinctly mentioned that it re-
ceives its roots, or connecting twigs, both from the posterior as also
the anterior roots of the spinal nerves."

Professor Mayer has succeeded in tracing the supposed origin of
the sympathetic into the spinal marrow itself, not only in animals,
but also in the human subject, and has given a drawing of the direct
and indirect connexion of the sympathetic with the spinal marrow
by the anterior and posterior roots of the second lumbar nerve.
Fig. 2 shows it in the human subject ; and fig. 3 in the calf, to the de-
scription of which he refers. According to this, he shows that the
sympathetic not only communicates by means of many twigs with
the ganglion spinale of the spinal nerves,and thus, with their posterior
roots, but that one, two, or even three insulated twigs of the sympa-
thetic are distinctly continued with those of the anterior root into
the spinal marrow.

"The nerves," says Professor M., "if I may so express myself,
show a remarkable predilection for decussating or crossing. An
arrangement of this kind I have observed in the cardiac nerves ;
the left branch passing to the right ventricle and pulmonary artery,
the right to the left ventricle and aorta. This is not very distinct
in the human subject ; whereas^ in animals it is much more so, and
remarkably so in the horse." — "On the other hand, this arrangement
of the nervous fibrillse in the central parts of the nervous system,
— viz. the brain and spinal marrow, — is only observed at one spot,
viz. at the origin of the corpora pyramidalia. I have always been

206

EXPERIMENTS ON THE

able to detect this decussation in the human subject, although of
variable extent ; whereas, in many mammalia, it does not exist at
all ; in others, again, it appears."

DESCRIPTION OF THE PLATES;

Figure 1.

Portion of the spinal cord from
which the 3d and 4th cervical nerves
arise. Front view, in the human
subject.

1. Third cervical nerve. 2. Fourth
cervical nerve. 3. Fifth cervical nerve.

a. Medulla spinalis.

h. Posterior root of the 3d cervical
nerve, consisting of five thick cylindri-
cal twigs, and passing into the ganglion
spinale.

c. Anterior root of the 3d cervical
nerve, consisting of three thin flattened
bundles with tapering extremities.

d. d. Accessory nerve, passing
downwards between the two roots of
the 3d and 4th cervical nerves.

e. Posterior root of the 4th cervical
nerve, consisting of two large and thick
bundles of filaments, of which the
superior gives oE a communicating
branch to the posterior root of the 3d
cervical nerve. They form the gan-
glion spinale, from which arise

f. A cutaneous cervical branch, and

g. A muscular branch to the scaleni.
h. Anterior root of the 4th cervical

nerve. An upper branch is observed
arising by three filaments from the
spinal cord ; it then receives a com-
municating filament from the lower
branch, takes its course to the ganglion
spinale, and, passing over it, forms,
with another superficial branch, the
superior root of

i. The phrenic nerve. A lower
filament of the anterior root is also
seen, which joins the phrenic nerve, as

k. The inferior root of the phrenic nerve. Between these two
roots of the phrenic nerve {i, A;,) four slender filaments are observed,
which come off from the ganglion spinale.

/,./. After this origin, the trunk of the phrenic nerve communi-
cates with the cervical nerve, and then passes downwards.

BRAIN, SPINAL MARROW, AND NERVES.

207

Figure 2.
A portion of the spinal cord from the lumbar region, with the
origin of the sympathetic and of the 2d lumbar nerve at this spot,
in the human subject.

a, a. Portion of the spinal cord from the lumbar region, seen
from behind.

b, b. Two filaments of the posterior root of the 2d lumbar nerve.

c. Ganglion spinale, formed from the above filaments.

d. Ramus muscularis dorsalis of the 2d lumbar nerve.

e. Anterior branch of the same (Ramus ileo-inguinalis).
f,f. A. part of the lumbar portion of the sympathetic. .

g, h, i. First, second, and third lumbar ganglion of the sympa-
thetic.

1, 2, 3, 4. Four branches of the anterior root of the 2d lumbar
nerve, dissected from each other.

The upper branch (1) takes its course outwards, and, passing by
the ganglion, assists to form the branch d, e. The branches 2 and
3 unite during their course, but again separate, so that No. 2 passes
into the trunk of the nerve e, which is formed of filaiments from the
ganglion and No. 1. No. 3 joins the sympathetic. The 4th branch
passes distinctly by itself into the sympathetic.

208

EXPERIMENTS, ETC.

k. Filament of communication between the 2d lumbar nerve and
the sympathetic, dividing into two branches h and m.

I. The upper branch gives off a twig to the nerve e, and then
passes into the 3d branch of the anterior root of the 3d lumbar
nerve.

7n. The lower branch divides into four filaments ; of which, the
anterior passes into the nerve e, having previously united with the
branch /, by a twig at n. Two other filaments unite with the
ganglion spinale, and the fourth goes to form the branch No. 4 of
the anterior root of the second lumbar nerve.

Figure 3.

Portion of the spinal cord at the origin of the second lumbar
nerve, in the calf

a a. Anterior surface of the medulla spinalis.

b. b, b, b, b. Five branches of the posterior root of the second
lumbar nerve,

c. Ganglion spinale formed from the above.

d. Ramus dorsalis of the second lumbar nerve.

e. Ramus anterior of ditto.

f,f. Part of the lumbar portion of the sympathetic nerve.

g. Second lumbar ganglion of ditto.

h. Anterior filament of the anterior root of the second lumbar
nerve.

i. Branches connected with the lumbar ganglion by two twigs,
and continued directly to the spinal cord. Two communicating
twigs pass thus to the following branches.

k. Second branch of the anterior root of the second lumbar nerve,
which receives the two above-mentioned twigs of communication
from the former, passing into d and e.

L Two branches of the sympathetic extending to the ganglion
spinale.

m. Twelve filaments of the sympathetic, which unite with the
trunk e.

VITAL STATISTICS.*

A STATISTICAL account of the British Empire was much wanted.
Englishmen have long hugged themselves in the belief, that they
excel all foreigners in occupations and in inquiries which practically
affect the business of life. The long wars with the French, and
our exclusion from the Continent, while they threw us on our
national resources, encouraged our national industry, and exhibited
our national energy, fostered at the same time that exclusive spirit
which has been said always to characterise islanders, and which, like
individual conceit, is too apt to engender ignorance and repress
improvement. It is now admitted that, in many respects, the Con-
tinental Nations excel us, and in few more than in the application of
science to matters of administration.

This is not the place for any but medical discussions, and we
have no intention of adverting to those parts of Mr. M'Culloch's
elaborate and valuable work, which do not immediately affect us.
In short, our business is with vital statistics, and vital statistics
only.

A chapter is devoted to them in the second volume, and its com-
position has been entrusted to Mr. Farr, who appears to have exe-
cuted it with ability and care. The chapter in question occupies
thirty-five pages, and is too much condensed, and too circumstantial
to enable us to present a complete account of it. Indeed that would
be unnecessary, as some of it is familiar to the medical reader.
Another circumstance which precludes our pursuing the writer
in detail, is his occasional disregard for simple and obvious arrange-
ment.

The subjects to which we shall first advert, are those involved in
the mortality of the population.

It appears that the annual mortality is about 2*13 per cent. That
mortality varies with age, sex, occupation, and locality.

1. Influence of Age on Mortality. From birth to the age of
puberty, the sickness and mortality decline ; from puberty they
increase slowly, but in a geometrical progression, up to the 50th or

* 1. A Statistical Account of the British Empire ; exhibiting its Extent,
Physical Capacities, Population, Industry, and Civil and Religious Institutions.
By J. R. M'CuUoch, Esq. assisted by numerous Contributors. In 2 Volumes
8vo, pp. 630-692. Charles Knight, London, 1837.

2. Medical Statistics, or the Causes and Effects of the Extension of
Human Life. By J. F. Palmer, Senior Surgeon to the St. George's and St.
James's Dispensary, &c.

m 20

210

VITAL STATISTICS.

60th year, and then more rapidly to the end. The following table
will show the ratio of mortality to age in the countries specified.

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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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9-3

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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on

We observe, first, that the whole mortality hasmaterially decreased.
Fever, plague, dysentery, cholera, (with the exception of the late
epidemic,) and small-pox, have diminished in a striking manner.
Measles and scarlet-fever have increased, yet, as Mr. Farr observes,
the mortality of all three diseases — of small-pox, measles, and scarlet
fever conjoined, is only half as great as that formerly occasioned
by small-pox alone. Fever has declined in nearly the same ratio
as small-pox. Consumption has decreased. It would appear that

224 VITAL STATISTICS.

fevers and consumption prevail together. It is very prevalent
among the British troops in the West Indies. We know that the
same causes tend to produce both fevers and consumption. Insuf-
ficient food and clothing, and exposure to wet and cold, are prolific
sources of both.

7. Fatal Diseases at different Jiges. The data for establishins;
this desirable information are not numerous. But the accurate
registration, which the working of the Act lately passed ensues, will
speedily remedy the deficiency that we complain of Seven tables
founded on the data that we have, are given in the work before us.
But they are too long for us, and their insufficiency will justify our
neglect of them. From the remarks appended to them, we shall
make two extracts.

1. ^^ What is the effect of the selection exercised by the assurance
companies ? What class of diseases does it exclude ? In the first
place, the eruptive fevers. Among 4,095 deaths in the Equitable
Society, only one was of small-pox. The deaths from consumption,
instead of making 20, only amounted to 8*3 per cent, of the deaths,
or 10"3 if those who died of ruptured blood-vessel be added.
But by way of compensation, the deaths from dropsy are 32 ; from
apoplexy and palsy 37 per 1000 ; instead of 11, 12, and 11, 10-6
the proportions dying of these two classes of disease in Carlisle and
Philadelphia. The advantage to the assurance offices of applying
tables founded on a city population in the last century, and including
all the sick, to a class of persons in good health, and little liable to
the eruptive fevers or consumption, is obvious. With a little study
the selection of long-lived persons may be carried to a still greater
extent."

2. Life, divided into five vicennial periods, is most secure in the
second ; the fatality of nearly all diseases increases afterwards in a
geometrical progression. Even consumption is not an exception to
this law.

3. With the civilization of a people, apoplexy increases. This is
apparently not difficult of explanation. Apoplexy is, in the great
majority of instances, the consequence of diseased cerebral arteries,
and the latter usually coexist with hypertrophy of the left ventricle
of the heart. In civilized life, the exertions of the brain, and the
influences of the passions on the heart, multiply to an almost incal-
culable extent. What wonder that both should suffer in their or-
ganization ?

" One of the most important results presented in this paper is, that
the character of diseases changes in a determined ratio at different
periods of existence. The tables indicate not only the degree, but
the kind of danger, we have to encounter at all ages : for example,
in the second vicennial period (20^40), the deaths from consump-
tion at Carlisle constituted 50, at Philadelphia 34, in the Equitable
Society 26 per cent, of the deaths from all causes ; in the third
vicennium the nature of the danger has altered, for the deaths from

VITAL STATISTICS. 225

consumption contribute but 23, 28, or 11 per cent, to the entire
mortality. From tables of this description, the probability of death
from each class of diseases can be calculated at all ages. We will
add one instance of their practical application. In the first period
of life (0 — 20) the eruptive fevers, inflammations, scrofulous and
dropsical effusions, are most to be dreaded ; in Philadelphia two-
fifths of the deaths were from affections of the brain and bowels.
Who, with these facts before him, can fail to see the impropriety of
giving children preparations of laudanum, spirits, or any food at first
but the mother's bland milk ? Cold often produces inflammation
of the lungs in winter : but too much tenderness in this respect, and
the accustoming of boys to a delicate diet, weaken the constitution.
Between 20 and 40, consumption, inflammations, fevers, and epi-
demics, are the most deadly shafts of death, which, as Dr. Clark
has shown, a judicious course of hygiene in this period may do much
to disarm. The same class of diseases maintains the preponderance
till 60 ; but, in the period following (60 — 80) dropsies and inflamma-
tions increase, while apoplexy gains a great ascendency. After 65 a
man should undertake nothing requiring great intellectual exertion, or
sustained energy : warmth, teniperance, tranquillity, may prolong his
years to the close of a century ; a rude breath of the atmosphere, a
violent struggle, or a shock, will suffice to terminate his existence.
The apoplexy of the aged can, with care, be averted for several years ;
but it is, perhaps, the natural death, the euthanasia of the intellectual :
their blood remains pure, the solids firm to the last, when a fragile
artery gives way within the head, — the blood escapes, and by a
gentle pressure dissolves sensibility at its source for ever."

We have reached the termination of the chapter. It concludes
with a few and but a few " conclusions," which wear, after the long
array of figures and of facts, a rather lame appearance. They may
be readily summed up. That governments should ensure an accurate
registration — that all classes are ignorant of physiology, and that
therefore the works and inventions of Rumford and of Arnott will
be useful — that prevention is better than cure, and quite as easy —
that the medical institutions of the country should be liberal — that
" medical writers should renounce the notion that a science can be
founded on the limited experience of an individual" — that practical
medicine cannot be taught by books, while the science of medicine
cannot be acquired in the sick room — that morbid anatomy is in-
dispensable— and, finally, that,i\ie Government, municipal and gen-
eral, should do their utmost to render towns healthy — are the in-
ferences deduced from the statistical data set forth — inferences, most
of them just, but oddly sorted, and some of them not very obviously
inferential. The reader in fact is almost tempted to apply to them
the pasquinade upon the ill-placed columns: —

Care colonne che fate qua?
Non sapiamo, in verita.
Ah, my dear columns, what do you there ?
Of that, we've not an idea, we declare.
21*

226 VITAL STATISTICS.

The author, in urging the prevention of disease, anticipates and
endeavours to parry a professional objection. That objection is
obvious and natural. If diseases can be materially prevented, if
public hygiene proves as successful as we are told it may, what is
to become of the present myriads of doctors ? Mr. Farr supposes
that a modified system of medical education, and of remuneration
for medical services, will correct that evil, and will fill the gaps in
the ledger and the pocket. A sanguine but extraordinary notion.
The doctors, like other folks, are paid for work done, and it requires
but a small share of economical knowledge to foretel, that their
payments will decrease when there is little work to do. Fortunately
even the statisticians cannot yet prevent epidemics, and once every
four or five years at least, the faculty may expect to obtain a good
dinner. An iron age is evidently approaching, and we recommend
our brethren to seize the present moment, (the influenza is on its
wing,) ere it is for ever flown. Pills will soon be a drug, draughts
will be dishonoured, the only bills sent out will be bills of mortality,
and they will be small and payable long after date. The statisticiansr
themselves will, after a short season, find their occupation gone, and
the dead will be too few to afibrd them a living. That practical
philosopher, Mr. Reeve, has anticipated the coming state of the pro-
fession, and we must shortly admit with him, that " there is nothing
stirring but stagnation."

The article on medical statistics, contained in the Dublin Review,
and contributed by Mr. Palmer, is a clear, judicious, and well-written
exposition of the causes that have contributed to the extension of
human life. Addressed to the public, it is calculated to engage its
attention, and to set before it in a plain yet striking manner, the
means of securing health and attaining longevity. The length to
which this article has run, in pursuing the more elaborate details of
the preceding author, precludes the possibility of our going far with
Mr. Palmer. We can only select a few points from his paper, which
either illustrate those that we have already dwelt on, or supply
deficiencies which thei/ exhibit.

Mr. Palmer traces with care and satisfaction the causes of the
demonstrative augmented value of life — a value higher in this calum-
niated country and climate than in any other in the world. Those
causes are general and medical. Among the former, cultivation of
the land and surface drainage — better clothing and better food than
formerly — increased commercial prosperity, are theprincipal, though
not the only ones. Those who talk of the " good old times," are
probably ignorant of what the real characters of those times were.
We would advise them to turn to our English history, and contem-
plate those ancestors, whose situation they conceive to have been so
incomparably superior to their own. We may mention a fact or two
for the benefit of those who admire so much not only the wisdom but
the manners of our ancestors.

It was not till the end of the reign of Henry VIII. that any salads,
carrots, turnips, or other edible roots were produced in England.

VITAL STATISTICS. 237

Queen Catharine, when'she wanted a salad, was obliged to despatch
a messenger to Flanders on purpose. In Edward the Sixth's reign,
which was after Henry's,* Erasmus ascribes the frequent plagues to
the nastiness, and dirt, and slovenly habits of the Englisih. " The
floors," says he, " are commonly of clay, strewed with rushes,
under which lies unmolested an ancient collection of beer, grease,
fragments, bones, spittle, excrements of dogs and cats, and every
thing that is nasty." Hollingshed gives a lively account of the
mode of living when Elizabeth came to the crown, at the close of
the sixteenth century. There was scarcely a chimney to the houses,
even in the considerable towns, the fire being kindled by the wall,
and the smoke finding its way out as it best might. The houses
were only watling, plastered over with clay. The people slept on
straw pallets, and had a good round log under their heads for a
pillow. Can we wonder at plagues and epidemic fevers prevailing
under such circumstances as these ; or, when we recollect the filthy
woollen under garments, that our ancestors, both the little and the
" great unwashed," were under the necessity of wearing, can we be
astonished thatthe present inhabitants of England should enjoy better
health, and a longer range of existence, than they did?

To the medical profession itself it would be absurd to dwell on
the influence which medical improvement must, ex necessitate, have
exerted, in efiecting the diminution of mortality. Yet there are
one or two statistical facts which we may quote. Out of 37 cases
of fever treated by Hippocrates, 21, or more than one-half, died;
whereas at the Fever Hospital of London, in 1S25, the total mortality
was less than 1 in 7 ; and at the Dublin Fever Hospital, from 1804 to
1812, did not exceed 1 in 12. Independently too of the decrease of
the numberof cases of small-pox, the diminution of fatality in the cases
that do occur is gratifying. From 1794 to 1798, the mortality, at
the Small-pox Hospital of London, was 32 in 100, or nearly 1 in 3 ;
but had diminished, in 1834, to 13 in 100, or nearly 1 in 8, a dimi-
nution which must principally be ascribed to the improved medical
treatment to which the patients are subjected.

But we must pause. This article has already attained a length
which precludes our adverting to further facts. As opportunities
occur, we shall return to the subject of vital statistics, and endeavour
to disseminate the accurate data and important conclusions that it
furnishes.

* Anno Domini, 1553.

PROGRESS

OF

THE ANATOMY AND PHYSIOLOGY

OF

THE NERVOUS SYSTEM

• DURING THE YEAR 1836.

BY PROFESSOR MULLER, OF BERLIN,

Inquiries into the minute structure of the nerves form an unusually
large proportion of the scientific communications of the past year.
Besides Ehrenberg's* excellent work, we have a treatise by Valentint
full of interesting observations on the ganglia and on the terminations
of the nerves. EmmertJ has traced the distribution of the extremi-
ties of the nerves in the muscles. Gottsche§ and TreviranusIT have
examined the structure of the retina, and Treviranus that of many
other parts of the nervous system. Volkmann|| and Langenbeck**
have directed their attention to these and similar objects, and Kro-
nenbergtt has investigated the structure of the plexuses. These
labours, as well as those of Remak,f J have for their object the rich
and still unexhausted topic of the minute anatomy of the nervous
fibre.

*Ehrenberg in Abhandlungen der K. Akademie der Wissenschaftenzu Berlin
aus d. J. 1834.— Berlin, 1836. p. 605.

f Valentin iiber den Verlauf und die letzten endender Nerven. Nov. act. nat.
Vol. xviii. p. 1. p. 51.

t Emmert iiber die Endigungsweise der Nerven' in den Muskeln. Bern,
1836.4.

§ PfafF's, Mittheilungen aus dem Gebiet der Medicin, Chirurgie, und Phar-
macie. Neue Folge — Altona. Heft 3. 4. Heft 5. 6. (See Brit, and For. Med.
Rev., Vol. iv. 499.)

^Treviranus, Beitrage sur Aufklarung des orgnischen Lebens — Bremen 11.

II Volkmann, Beitrage zur Physiologie des Gesichtssinns. — Leipz. 1836. 8.

** Langenbeck de Retina Observationes Anatomicae-pathologicas. — Gotting,
1836. 4.

ft Plexuum Nervorum Structura et Verlutes. — Berolini, 1836. 8.

ii Miill. arch. p. 145,

230 REPORT ON THE NERVOUS SYSTEM.

The distinction of the nerves according to their fibres becomes
more and more difiicult. Treviranus found the fibres, in the recent
subject, in the brain as well as in the nerves, for the most part
straight and uniform ; Volkmann, that the varicose fibres in the
nerves of sense (the optic nerve) are not constant ; whilst Remak's
observations prove that it is impossible to classify the nerves accord-
ing to their varicose or cylindrical form, as single varicose fibres
were seen more or less frequently in the most different nerves.
And to denominate those fibres organic, which are to be found dis^
tributed alike in the nerves of sense and motion, is forbidden by
their great changeableness and the impossibility which exists to
draw exact limits between the cylindrical and varicose fibres : for
one and the same fibre is often alternately cylindrical and varicose,
and the nervous fibres in young animals are generally more inclined
to this latter form. But even the existence of varices in nerv-
ous fibres which are not exposed to any disturbing cause is become
altogether a matter of doubt. Treviranus was the first who ex-
pressed this doubt. The articulated form of the fibres of the
brain is, no doubt, an observed fact ; but this form is produced,
according to Treviranus, by the influence of air and water ; accord-
ing to Valentin, by tension ; and, according to E. H. Weber, by
water and pressure combined. Weber, therefore, examined the
nervous fibres uninfluenced by these disturbing causes, by merely
moistening them with albumen. He then found, in common with
Valentin, that, when he was able to isolate thin lamella of the brain,
as, for instance, the delicate layers of the valvula cerebri, without
pressure or stretching, the fibres had the appearance of nearly uniform
tubes ; and both observers agree in ascribing this structure to the
fibres of the brain. There seems, indeed, to be no longer any doubt
that the fibres of the brainand of the nerves, examined in a recent state,
and independent of all disturbing causes, approach mostly to the cy-
lindrical form, though they are not everywhere, perfectly uniform, or
free from slight irregularities. It is always, however, a characteristic
of the fibres of the brain and of the nerves of sense, that they very
readily assume this form, which is the case with no other tissue ;
this character, therefore, cannot be omitted from a definition of these
nerves, and may be usefully applied in the discrimination of doubt-
ful cases. It is not exactly made out on what this property dis-
covered by Ehrenberg depends ; the cause is probably to be found
in the unequal cohesion of the tubes or of their contents. According
to E. H. Weber's observations, unevenness and bulging out of the
sheath which surrounds the soft contents, (a protrusion which occurs
more on one side than on the other,) arise under the eye of the
observer during protracted examination. As far as the contents of
these tubes are concerned, they are, according to Valentin, perfectly
clear, transparent, oily, and without any trace of globules, and the
fibres, with the exception of a different degree of softness in the
walls in the central parts, are throughout identical in the centre and
in the periphery of the nervous system. This point, namely the
proportion which the sides of the tubes bear to their contents, with

REPORT ON THE NERVOUS SYSTEM. 231

the discrimination of which the modern minute anatomy of the
nervous fibre began, is still one of the most difficult subjects of inves-
tigation. Valentin does not express himself everywhere with equal
confidence on this question. According to him, the substance of
the primitive fibres is everywhere a half-fluid, slightly adhesive and
transparent oily substance, which, in consequence of its refractive
power, shows, when isolated, a finer internal line parallel to its super-
ficies, without being, for this reason, divisible into a tube and its
contents ; when isolated it assumes either the globular form of all
fluids or at least that of a flattened sphere. The contents, however,
may readily be pressed out of the varicose fibres, so that the mere
sheath remains. He describes the expressed contents of the tubes
of the nervous fibres as a grumous mass, consisting partly of divided
and curved threads, and partly of isolated irregular globules, between
which again are other globules isolated, oily, perfectly transparent,
regularly or irregularly swollen, and exceeding for the most part
in thickness the thread-like tissue of the brain and spinal marrow.

Whether or not the minute elementary structure of the nerves is
known, must still remain a matter of doubt. These large cylinders,
which are called primitive fibres, greatly exceed in strength the
elements of other tissues. Schwann saw, in fibres of the thickness
of the primitive fibres of the mesentery of a frog, still finer fibres
running out of them. Treviranus discovered stripes running in the
length of the cylindrical tubes, he even saw distinctly smaller ele-
mentary cylinders in the primitive fibres, the first having a diameter
of 0,0013 mili metres, the latter of 0,0053 in a spinal nerve of the
Crucian [Cyprinus Carassius, Linn.) In rabbits the elementary
cylinders were 0,0016 in diameter, and the stronger cylinders enclos-
ing these, and called the primitive fibres, 0,0099. In his latest
observations Remak observed the contents of the nervous tubes to
be a somewhat smaller, flat, and quite solid thread ; or a flat, pale
fillet which could be isolated from the easily wrinkled tube in large
pieces by pressure. He did not succeed in detecting a more minute
fibrous structure in this fillet, although, in some cases, it would be
split into two or more fibres.

Much also still remains to be observed in the minute anatomy of
the primitive fibres of the central parts, before general physiological
conclusions can be formed. In some animals there are striking
exceptions, as, for instance, in the spinal marrow of the Cyclosto-
■mata. The spinal marrow of the Petroniyzon is generally known
to be extensible ; it can easily be torn into threads, which may be
regularly pulled ofi'in the direction of its length. In the examina-
tion of these parts I find that, in the spinal marrow of the Petro-
myzon marinus, there are different kinds of fibres, consisting of
flat, thin, band-like threads, as broad as the primitive fibres of the
nerves of the ox. I have never seen such bands in the spinal marrow
of any other animal. These flat bands exist in all parts of the spinal
marrow, their edges are parallel and without swellings of any kind,

232 REPORT ON THE NERVOUS SYSTEM.

and they are pale, transparent, not divided into a tube and contents,
nor can any minute structure be discovered in them : they do not
join together, nor do they give off branches. Besides these, there
are somewhat finer threads, of which it is difficult to say whether
they also are flat ; and there is moreover a peculiarly fine fibrous
structure, consisting of other fibres which are greatly more minute
even than those already mentioned.

Concerning the distribution of the nervous fibres in apparent anas-
tomosisand plexus, Kronenberg's communications are very complete.
His researches give additional confirmation to the assertion that the
primitive fibres of the cerebral nerves continue separate up to their
ultimate distribution, that they merely change from one bundle to
another, a change which takes place not only in the plexus but in
every part of the nervous trunks and branches. No one has hi-
therto studied with so much perseverance as Kronenberg the comport-
ment of the fibres in the several plexus : the researches which this
author has made into the minute structure of the brachial plexus of
the mammalia and of the lumbar plexus of the frog form a very good
foundation for physiological experiments. We shall again refer to
the physiological part of these researches.

The ultimate distribution of the nerves has been illustrated by the
labours of Treviranus, Gottsche, Valentine, and Emmert. Although
Schwann's investigations were less favourable to a loop-like termina-
tion of the primitive fibres in corresponding ones distributed to the
muscles, and Treviranus stated that he had observed a sudden ter-
mination of the primitive fibres in the muscles without minuter
subdivisions, the observations of Valentin and Emmert tally with
the opinions of Prevost and Dumas, who had not themselves ex-
amined the primitive fibres. The same distribution has been observ-
ed by Valentin in the iris and ciliary ligament, and even in parts
exclusively sensible, as in the interior of the cochlea of birds, in the
ampullas, in the sacks of the teeth, and in the skin of the frog.
Breschet saw this distribution in the cochlea and ampullae, and in
his earlier examinations of the papilla of the skin. Burdach, junior,
also hit upon the same loop-like union of two fibres, as stated in a
Written communication to me on the examination of the nerves in
the skin of a frog, and he saw these loops formed by the fibres of
different branches of the nerves. It would be very difficult at pre-
sent to form any conclusion from these observations respecting
further propositions in the physiology of the nerves, as every such
conclusion must rest upon the hypothesis that the so-called primitive
fibres are really the minutest parts of the nerves. Even if this were
the case, we should still hesitate to consider the loop-like union of
two primitive fibres with each other as a general fact, as regards the
nerves of sensation ; for this does not occur in the retina of verte-
brated animals and of insects, in both of which the nervous fibres
continue separate to their termination. As to the organ of hearing,
I have lately convinced myself that it is just as little the case in the

REPORT ON THE NERVOUS SYSTEM. 233

lamina spiralis, the most important part of the cochlea of birds. The
largest portion of the nerve of the cochlea lies upon the edge of the
cartilage of the cochlea, and distributes its branches very regularly
to its substance. A number of minute fibrillag arise from the cartilage,
and pass transversely close together and in parallel lines through
the greater part of the breadth of the lamina spiralis. These trans-
parent fibrillse are much more minute than the primitive fibres of
the nerves, and end indistinctl}'^ without coalescing. In all proba-
bility they are the continuations of the primitive fibres of the nerve
of the cochlea which pass through the cartilage, and are here divided
to the utmost degree of minuteness. The difference between these
fibrillae and the darker nervous fibres before they enter upon the
cartilage, may perhaps depend upon the absence of their sheaths and
tubes. The lamina spiralis of the cochlea of birds, first discovered
by Windischmann, is undoubtedly the most important part of the
cochlea ; and I cannot therefore agree with Huschke in considering
the arched and wrinkled vascular membrane, falsely called the
membrane of hearing (Gehorblatter) as such. Breschet also agrees
with what has been stated on this subject. The nerves of the cochlea
are not distributed to the lining membrane (Gewolbten Haut) ; the
sac (Flasche), on the other hand, receives numerous nerves, but I
have never succeeded in tracing the loops of the primitive fibres,
and observed merely plexus consisting of bundles of minute fibrillse.
In reference to the present state of the physiology of the nerves,
the question whether or not the fibres of the nerves of sensation ter-
minate by loops is of no moment. The conclusions to which we
have arrived depend, in no degree, upon this alternative ; and, as it
is certain that the truncated ends of a divided nerve are as capable
of sensation as the extremities of the nerves themselves, it is also
clear, h priori, that if the loop-like connexions of the extremities of
the fibres of the nerves of sensation do exist, it can make no differ-
ence, as, after the removal of these loops by dividing the nerves, the
result remains the same. Treviranus found a papillary termination
of the nervous fibres not merely in the retina, but also a similar dis-
tribution in the auditory and olfactory nerves. In these latter nerves
the papillae are more thread-like. He examined the auditory nerve
in the lamina spiralis of the cochlea of young mice, and found the
bony part entirely covered by thread-like papilla, lying close the
one on the other. The cylindrical fibres of the nerve pass more
disunited underneath the lining membrane of the cochlea to the
membranous edge of the lamina spiralis, and after making numerous
gyrations in the canals which contain them, pass through small
openings and make their appearance externally as minute sound
globules, having a diameter of from 0,0016-0,0033 milimetres. The
cylindrical fibres of the auditory nerve itself had the same diameter.
Treviranus found that, in the fox, the nerve of the semicircular
canals, at their entrance into the ampullae, expand on each side into
a sheet in which the cylindrical fibres subdivide into still more
minute cylinders, and again reunite to form still larger cylindrical
m 22

234 REPORT ON THE NERVOUS SYSTEM.

fibres. The line of this reunion is marked by a dark ring, which
consists of very minute cylinders. In a turkey-cock the extremities
of the nerves had the appearance of bundles of extremely minute cy-
linders, and seemed to spread themselves over the internal surface of
the ampullae. In a bream, the nerves, which, before their entrance into
the ampullae, had a diameter of 0,0066 milimetres, terminated after
their entrance in cylinders of 0,0010-0,0015 milimetres. Gottsche
found the extremities of the nerves of the cochlea in hares and rabbits,
and of the acoustic nerve in fisli (Platersaborealis) club-like. In many
fish, for instance in the sturgeon, the auditory nerve divides into
threads which appear truncated ; but in the place it forms, according
to Gottsche, swellings which are twice as thick as the fibres them-
selves : these swellings contain in their interior a cavity, and the
nervous fibres themselves exhibit a complete canal. In hares the
nervous cylinders terminate upon the cochlea by egg-shaped knobs,
which are distinctly raised above the internal membrane of the
cochlea, like flower-buds. Treviranus found the papillae of the ol-
factory nerve of mice thread-like and elongated ; in the mouse they
lie close to each other, but in the hedgehog they are more isolated.
Their diameter is from 0,003 to 0,005 milimetres. Upon the lining
membrane of the nose of the turkey-cock, turtle, and bream, he saw
merely the blunt extremity of the minute cylinder, without any
projection.

Inquiries into the minute anatomy of the retina have yielded a
great deal of information. E. C. R. Langenbeck has been able to
distinguish in the retina, 1, an external granular coat, (the cortical
layer;) 2, Ehrenberg's filamentous nervous coat ; and 3, a vascular
coat, consisting of blood-vessels, which are united by much cellular
substance into a delicate membrane. He found the fibres in the ner-
vous coat, as in the optic nerve, varicose. Volkmann also made the
same observation, but states that the varicose appearance is not con-
stant, the swellings being at times entirely absent. These discrepan-
cies no doubt partl)^ depend upon the time and manner of observing.
In recent eyes of mammalia and fish, I saw the fibres in the optic nerve
as well as in the nervous membrane without swelling of any kind,
and much more minute than they appeared when examined later.
In the brain of different animals also I saw the fibres, when not
submitted to pressure, very frequently at least, with almost straight
outlines, and when pressed upon swollen and irregular. In the
situation of the 7nacula flava of the retina, Langenbeck observed
that the granular layer terminated only by a sharp edge ; where the
retina borders on the ciliary ligament, the granular layer of the
retina also terminated, and the fibrous coat becoming much thinner
formed what our author calls the ciliary part of the retina ; this part
lies upon the ciliary ligament, overlaps the posterior edges of the
ciliary processes, is continued to their anterior edges, and terminates
at the junction of the capus ciliare with the uvea. This prolongation
is said to contain small articulated tubes. Langenbeck saw the ves-

REPORT ON THE NERVOUS SYSTEM. 235

sels of the retina in connexion with those of the ciliary ligament in
the foetus of the pig. Treviranus does not recognize any ciliary
2)art of the retina. At some little distance from the roundest edge
of the retina he could distinguish neither the vascular membrane nor
Jacob's membrane. Near this edge, however, both its surfaces were
covered with delicate membranes, of which the external was homo-
geneous and the internal highly vascular. Both of these membranes
were prolonged over the edge of the nervous coat, they then lay close
together, were formed into long folds, and extended to the ciliary
ligament. The most careful examination detected no nervous matter
between these membranes.

The exact relation which the coasts of the retina bore to one
another had hitherto remained unknown ; we therefore stated some
years since that its exact structure semed problematical. Treviranus
has made a great step towards the elucidation of this subject ; and
his discovery, published a little before his death, was the last benefit
he conferred on science. The chief part of this discovery is shortly
expressed in the author's own words. The optic nerve divides into
nervous cylinders, which radiate upon the external surface of the
retina. Each separate cylinder, or each bundle of cylinders, devi-
ates at a certain point from the horizontal direction, and turns towards
the opposite internal surface of the retina. Soon after it has changed
its direction it passes through oj)enings in a vascular network which
springs from the central vein of the optic nerve. Before it reaches the
internal surface of the retina it penetrates a second vascular network
derived from the last branches of the central artery. After it has
passed through this last it is covered by a sheath-like continuation of
the vascular membrane of the retina, and ends behind the vitreous
humour in the form of a papilla. The transverse diameter of the cy-
linder was, in the hedgehog 0,001 milimetres; in the rabbit 0,0033,
and in birds 0,002-0,004 ; in the frog the cylinders had a diameter of
0,0044 milimetres, thepapillse of 0,0066,and thelatter in the Crucian
of 0,0039-0,004 milimetres. Ehrenberg recognized also in the retina
of frogs and fishes staflf-shaped bodies, whose connexion with the
nerves seemed indistinct ; he saw also club-like bodies in the Schnei-
derian membrane of the nose. Gottsche's observations contain many
interesting details in illustration of the discovery of Treviranus.
The so-called granular membrane of former writers, concerning which
so many different opinions have been broached, is not found in re-
cent eyes. If we observe a perfectly recent retina, we see, according
to Gottsche, an appearance similar to a thatched roof, and small dis-
tinct nervous cylinders project out of it ; if we let this remain
upon the glass and moisten it from time to time, we see distinct gra-
nules ; the Qye of a fish which has been dead from three to four
hours has the same appearance. We agree perfectly in this remark.
Upon the internal surface of the retina of recently killed mammalia,
frogs, or fishes, we distinctly perceive the staff'-like cylinders pro-
jecting from the surface, presenting an appearance like a thatched

236 EEPORT ON THE NERVOUS SYSTEM.

roof. Sometimes we see these cylinders externally, as Gottsche
also states. Michaelis thinks that they are merely seen through the
membrane, an opinion with which I fully agree. The little cylinders
are easily broken off, and swim about in a detached form ; when
separated they are much longer than broad ; in frogs I have often
seen them of unequal lengths, and some of these are slightly bent.

Volkmann and E. H. Weber have confirmed the statements of
Treviranus in respect to mammalia : they saw the fibres always
tortuous, but without papillae, which indeed are not present in mam-
malia, but merely the staff-like bodies. The fibres of the retina were
obviously free from swelling, but they saw some varicose fibres (in
rabbits) which were not produced by water, for they employed the
aqueous humour and avoided using pressure in their observations.
The swollen fibres were more visible in the brush-like expansion
of the optic nerve, and were situated by the side of and between the
uniform fibres. In frogs both these observers saw all the fibres at first
uniform and free from enlargements.

I make the following extract from a treatise on the structure of
the retina which Dr. Michaelis has communicated to me in manu-
script, and which is about to appear in the nov. act. net. cur.

According to Michaelis the retina extends only to the ciliary
ligament, for so far only does the granular membrane and the expan-
sion of the optic nerve proceed. He found the structure most dis-
tinct in a young owl. In this case the thick, defined, projecting
border of the ciliary ligament overlaps the edge of the retina, whilst
half the thickness of the retina lies above, and the other half below
this border. On the other hand, in the pig, the retina, prominent
and abruptly cut off, lies over the ciliary ligament which firmly
attaches itself by a defined margin to the inner surface of the retina.
In the calf, again, the retina becomes thin at its edge, and attaches
itself to the ciliary ligament by a sharp border. In men the ciliary
ligament projects over the retina externally by a zigzag edge, and
under this covering the retina first becomes thin.

Michaelis describes four layers in the retina : an external serous
layer, a granular layer, a nervous and vascular layer, and lastly an
internal serous layer. The external layer is the membrane Jacobi:
in mammalia this membrane shows under the microscope only slight
dimples ; in the heron they appear in regular and clear divisions
sprinkled with small blood-red globules, having a diameter of 3^
of a line, and between these there are still other globules more minute
and of a citron-yellow colour : these globules adhere only to the
external surface. In owlets they are of a bright yellow colour. The
second or granular coat is the thickest membrane of the retina, and
exhibits both on its external and internal surface a globular forma-
tion ; when fresh it is as clear as water, but after death and under
the influence of chemical agents it becomes opaque, whilst the ner-
vous membrane remains transparent both in spirit and water. When
divided the cut surface seems to consist of cylinders standing upright,

REPORT ON THE NERVOUS SYSTEM. 237

closely packed, and bearing each upon the extremity which is in
contact with the nervous coat a small globule. It appears to be the
substratum of the nervous threads which run upon it ; in the situation
of the so-called foramen centrale it becomes thin, and has the appear-
ance of a mere granular coat. The fasciculi of the nervous coat are
best shown by means of spirit of creosote. Our author states the
thicknessof the fibres at 3 ^00 of aline. These fibres have very slight
and infrequent swellings ; in fish they are quite uniform. The trunks
of the vessels lie internal to the nervous coat. The serous or inner-
most coat is seen by maceration in dilute sulphuric acid. On the
surface which is in contact with the retina hang a number of minute
globules having a diameter of y-Joj- lines, and separated from each
other by tolerably regular intervals of i^o'sV lines. Most of these
little globules are furnished with fine threads of different lengths,
which resemble the primitive fibres of the nerves. Michaelis con-
siders these threads as the terminations of the nerves. The serous
membrane always remains attached to the retina after the separation
of the vitreous humour. Our author has not been able to ascertain
the exact connexion of the tunica Jacobi and of the internal serous
membrane of the retina with the ciliary ligament. The thickness of
the retina gradually decreases towards its anterior edge, where the
primitive fibres are separated and do not touch each other.

Michaelis has made many observations on the macula lutea ; at
this spot the granular membrane is very thin, but begins to increase
in thickness at ^ line from its centre, and obtains its greatest thick-
ness at a distance of |- line. This strong ring or ridge around the
foramen centrale, which foramen is formed by a single layer of little
globules, is the macula lutea. The fibres of the retina have a pecu-
liar arrangement around this point ; for whilst, in other situations,
the nerves radiate in straight lines from the optic nerves, around the
macula lutea they are arranged in the form of arches, of which one
part meet in the so-called foramen centrale, the next in succession
converge in a regular manner from each side towards a line which
stretches from the macula lutea. Between this spot and the optic
nerve the nervous fibres are less numerous, more or less straight,
and perfectly distinct the one from the other. The thin transparent
spot, which has obtained the name of foramen centrale, is not quite
round, but star-shaped ; in young subjects it is elongated.

Although the modern investigations into the structure of the
nerves are highly important, many things still remain to be deter-
mined. The termination of each separate fibre of the fibrous coat
in a staff-like body seems still rather a postulate than an ascertained
fact. For it is of the first importance to the physiology of vision
to know what proportion the number and size of the primitive
fibres of the optic nerve bear to the number and size of the termi-
nations of the nerves in the nervous coat, or to the number and
thickness of the staff-like bodies. If every extremity of a nerve
corresponded to a fibre of the optic nerve, the thickness of the retina
ought to progressively diminish from the point of entrance of the

238 REPORT ON THE NERVOUS SYSTEM,

optic nerve to the border of the ciliary ligament, independently of
the varying thickness of the other coats of the retina. The obser-
vations of Gottsche favour this supposition. It is not easy, however,
to understand how so many fibres as are necessary to furnish the
stafi'-like bodies can be compressed into the narrow compass of the
optic nerve. (Compare J. Miiller's Physiology, i. p. 688, and
Volkmann, a. a. 0. p. 104.) At all events, the fibres of the optic
nerves and the nervous fibrillse of the fibrous coat of the retina are
much more minute than the strong cylinders of other nerves. As
far as I have been able to compare the optic nerve of rabbits, and its
minute fibrillse distributed to the fibrous coat of the retina, vi^ith the
cylindrical tubes of other nerves of the same animal, I should say
that the union of many fibrilla of the retina or of the optic nerve
would be necessary to occupy as much space as the primitive cylin-
ders of any other nerve ; and the extraordinar}'^ minuteness of these
fibrillae clearly shows how small must be the staff'-like bodies in
the retina of the rabbit. Wagner also (Burdach's Physiology, v.
p. 143,) found the nervous fibres of the retina of the ox very minute
sU --wiv lines, whilst the cylinders of the ciliary nerve of the same
animal ranged from tIo- so o lines. The primitive fibres are most
easily examined in the optic nerve of fish. I have never seen any
fibres so minute as in the optic nerve and retina of rabbits, and in
the optic nerve of the cyprinus (probably these are varieties here).
It is difiicult to understand how the fibres, pressed into the small
compass of the optic nerve, should sufiice for the formation of so
large a surface as that of the retina, if this surface be formed, like mo-
saic work, by the extremities of the nerves. But if we assume that
the staff-like bodies are situated in rows upon the sides of the primi-
tive fibres, so that a greater number of them are attached to one fibre,
such a supposition is at variance with the theory of sensations ; for
the sensation of any one part does not appear to take place in the
length of the fibres of other nerves, but depends upon the number
of fibres, of which each has only one origin in the brain. If the
sensation of different parts took place in aliquot parts of the length
of the fibres, we must suppose the mind to be present in the entire
body, and in every minute part of the whole length of a fibre : with
such a supposition the sensation felt by those who have lost a limb
by amputation are at variance. But if sensation be conveyed to the
brain only from the extremities of the nerves, a fibre can refer every
change which takes place in aliquot parts of its length to one spot
only. For it would be absurd to suppose that the sensation of a
part depends on the different distances which the nervous principle
has to travel from the various points of a fibre to the brain. If, on
the other hand, we consider the superior nerves of sensation as dif-
ferent from the other nerves, and as participating more closely in
the operations of the mind, so that this is actively percipient in the
extremities of the nerves of the retina, the difficulty of supposing
the fibrillae of the optic nerve sufficient to form the entire inosaic

REPORT ON THE NERVOUS SYSTEM. 339

of the retina is at an end ; but other difficulties suggest themselves
into which we cannot inquire further at present. This state of the
question, which we have long considered, has determined us to
mention merely those facts in the physiology of the nerves which,
are clearly established, conscious how many things yet remain
unexplained and contradictory in the still unfinished theory of
sensation.

The observations on the decussation of the optic nerves refer
merely to the general course of the fibres, in respect to their cross-
ing or not crossing. Whether there were transverse unions or
divisions could be ascertained only by minute dissection. In the
decussation of the optic nerves Volkmann saw no divisions of the
fibres. I also looked for such divisions in vain, even when the cross-
ing of the crossing parts was very perceptible. Treviranus says
that many of the internal fibres appear to come in an arched form
both sides and to anastomose with each other ; but that these con-
nexions when they take place never extend to the primitive fibres.
He also saw them cross one another without uniting.

The terminations of the fibres in the brain have been examined
by Valentin. The primitive fibres of the nerves which join the
spinal marrow do not terminate there, but pass on to the brain.
The primitive fibres which unite with the extremity of the spinal
marrow run forwards ; those, on the other hand, which come lite-
rally from the higher nerves go first transversely inwards to or near
the cineritious substance, and then pass on in a longitudinal direction
to the brain. In the true medullary substance the fibres lie side by
side, but where the medullary and cineritious substances touch each
other they receive between them the globules of the cineritious
substance, which we shall presently mention, and radiate through the
cortical substance. Here they form loop-like terminations, as in the
peripheral extremities of the nerves. These fibres are most distinctly
seen at the union of the medullary and cineritious substance, or in
the yellow substance at the periphery of the hemispheres of the
cerebrum and cerebellum. In examining the latter, this appearance
has presented itself here and there. The existence of different sys-
tems of fibres on the surface of the cerebrum, those namely of the
crura cerebri and commissures, and especially of the corpus callo-
sum,and the presence of three distinct sets of fibres inthe cerebellum,
renders it doubtful to which system the different loops of fibres
belong. These loops do not appear to me to be exactly traceable
to the continued nervous fibres ; and we must give up the idea of
a complete and continuous circle of the nervous fibres, to which even
the observations of E. H. Weber concerning the origin of the ner-
vous trochlearis in the central line of the valvula cerebri are not
favourable.

The investigations also of the ganglia, and of the grey substance
of the central parts of the nervous system, have been very fruitful
in results. In the interior of the ganglia of the non-vertebrated

240 REPORT ON THE NERVOUS SYSTEM.

animals (leech, common snail,) Ehrenberg observed club-like bodies.
In the ganglia of the leech these clubs form eight bundles, of which
each pair pass through long tubes into the four roots of the ganglion.
These clubs contain in their swollen parts a nucleus, and in the
leech, in addition to these, numerous small globules. Valentin has
described similar bodies in the abdominal ganglia of the leech. He
saw globules which, like those of the ganglia of the higher animals,
contained a nucleus. On a spot near the surface of this nucleus is
placed a larger and redder body, and sometimes many swollen ones.

THE END.

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