nor of the phenomena of this combination; I should only be able to
repeat what others have said upon this point. I will merely remark
that it would be very important to try the effects of tannin on the
large sub-cutaneous aponeuroses, the texture of which being essentially
gelatinous has much analogy with that of the dermis, and which from
their extent and delicacy might serve for uses to which the dermoid
texture when tanned is less adapted. We know that the tanned skin is no
longer what it was in the natural state, and that the substance with
which it is then penetrated gives it an artificial consistence. If much
tannin has been combined with it, it loses entirely the faculty of
acquiring the horny hardness, and becomes brittle; whilst if but little
of this substance is added to it, it preserves in part its suppleness
and the property of crisping from the action of caloric. I would
compare tanned skin to bone penetrated with the phosphate of lime, and
that which is not tanned, to the cartilaginous parenchyma from which
the acids have removed this phosphate.
II. _Parts common to the Organization of the Dermoid System. Cellular
Texture._
The whole dermis is penetrated with a large quantity of this texture.
It is arranged in the following way; from the exterior of the
sub-cutaneous cellular layer, an infinite number of elongations is
detached which penetrate the contiguous spaces of the chorion, enter
afterwards into those which are more exterior, and finally terminate
in the numerous pores which transmit outwards the vessels, the nerves
and the hairs, which have previously passed through this cellular
texture. We can then consider the chorion as a kind of sponge, the
spaces of which represent the interstices, and which the cellular
texture penetrates on all sides; so that if it was possible to separate
by dissection, these spaces from the cellular texture, and the
organs which are in it, there would be a kind of sieve pierced in all
directions. Art cannot arrive at it but with difficulty on account of
the delicacy of the parts; but that which is not done by dissection,
nature often effects. In biles I have observed that all that which
fills the interstices of the dermoid fibres disappears by suppuration,
and that these fibres, separated besides by the swelling of the parts,
exhibit truly the appearance of a sieve of which I have just spoken,
when the fluid that moistens them is removed. The bile differs in
fact from many other cutaneous eruptions, in this that it attacks the
cellular texture of the spaces of the chorion, whilst they have their
seat, as I have said, in the reticular body. I do not know any acute
affection which attacks the chorion itself; all have their seat either
on its surface, or in the cellular texture of its cells. Its dense
and compact texture seems, like that of the aponeuroses, not able to
be changed until a length of time. In elephantiasis I have seen this
texture evidently disorganized.
M. Thillaye showed me portions of skin taken from a cemetery, in which
every thing that filled the dermoid spaces had disappeared, and in
which these spaces and their dried fibres formed a real membranous
sponge through which the light could everywhere be seen. In this case
the reverse of what is seen in long continued macerations had taken
place, in which the fatty cellular texture, changed into a solid, white
substance, preserves, as I have said, the form of the spaces which
it filled, whilst the dermoid fibres reduced to the pulpy state, are
easily removed. In the first case it is the mould only which is left;
in the second it is the substance which is contained in it.
In chronic leucophlegmasia, the sub-cutaneous serum gradually extends
along the cellular elongations of the spaces of the dermis, separates
their fibres, consequently enlarges these spaces, and sometimes
penetrates even to the epidermis, which it breaks in different places,
and through the crevices of which it escapes. In this case, there is
not resolution of the skin into cellular texture, as it is called, but
a separation of the dermoid fibres, which always remain.
I do not presume that the cellular texture of the chorion extends to
its external surface, under the epidermis; for when this has been
removed, fleshy granulations are not formed, now, in all the parts
where the cellular texture is found, these granulations are produced,
when the parts are laid bare.
_Blood Vessels._
The arteries winding in the sub-cutaneous cellular texture, furnish
an infinite number of small branches which are introduced with the
cellular parcels into the most internal dermoid spaces, afterwards pass
into those that are nearer, approximate by winding and anastomosing
a thousand times through the spaces of the external surface of the
chorion, finally go through the pores of this surface, and give rise to
that external capillary net-work of which we have spoken in the article
upon the reticular body, and to which in the ordinary state but very
little red blood comes. In this course through the dermoid spaces, but
few small arteries remain in the fibres of the chorion itself, as fine
injections prove. These fibres resemble in this respect those of the
aponeuroses through which many vessels pass, but which have but few
belonging to their own texture.
The veins follow nearly the motion of the arteries, but in an inverse
direction. After having passed through the dermoid spaces and the
cellular texture which fills them, they go to the great sub-cutaneous
trunks, which run a long course, form, as we have seen, a system wholly
distinct by its position from that of the arteries and which can be
often traced through the integuments. Not seen in the natural state,
the venous ramifications of the spaces of the chorion are considerably
dilated in the subjacent cancerous tumours, and make the skin which
covers these tumours appear to be marked with blue lines, which always
grow larger as the tumour increases. Whenever there is a considerable
distention of the cutaneous organ by an aneurism, pregnancy, dropsy,
&c. this dilatation also takes place, provided the cause of the
distention pursues a chronic course; for nothing similar is seen in
acute affections, whatever swellings may have taken place, as in those
consequent upon fractures, upon compound luxations, &c.
All the black blood formed in the skin goes into the general venous
system; no portion belongs to the abdominal.
_Nerves._
Their distribution is nearly the same as that of the blood vessels.
Many very considerable branches, as different divisions of the
musculo-cutaneous, the internal cutaneous, the lumbar, the saphena,
the anterior tibial, the intercostals, the cervicals, &c. form a kind
of sub-cutaneous nervous system, from which go all the branches that
enter the dermis. These branches, in passing through the dermoid spaces
with the arteries and the veins, appear to anastomose often together,
go through the pores which terminate the spaces on the interior, and no
doubt form the papillæ. Observe even that on the hand where the papillæ
are very evident, there are, in proportion to the surface, many more
sub-cutaneous nerves than any where else.
_Absorbents._
Many absorbents creep under the skin; it is here that they can be
the most easily studied. All the veins are surrounded with them;
various fasciculi are observed in their interstices; so that a layer
of absorbents, arranged in the form of a continuous layer, seems to
separate, in the extremities, the aponeurosis and the skin. There is
no doubt that the origin of the most of these vessels exists in the
chorion, that they carry to the blood the fat and the cellular lymph
of its spaces, and the nutritive matter of its fibres. But is there a
particular order of branches opening upon the surface of the epidermis
to absorb in certain cases foreign substances? This question cannot be
answered by anatomical inspection. But the following considerations
appear to me to throw great light upon it.
1st. The sub-cutaneous absorbents, visible by injections, are too
numerous in proportion for the mere purpose of carrying back the fat
and serum of the neighbouring parts.
2d. There are many medicines which appear to be evidently absorbed;
such are mercury in the venereal disease, various purgative and
emetic substances, febrifuges even, as cinchona, which, when applied
by friction, have produced their effects as well as if taken by the
stomach; cantharides often act upon the kidneys, when the tincture is
used as a liniment, narcotic substances sometimes occasion a weight in
the head and drowsiness when they have been externally applied, &c.
These different effects are well known and many authors have given
examples of them.
3d. There is we know absorption of different kinds of virus, of that
of hydrophobia, of the small-pox, of the venom of the viper, &c. an
absorption, it is true, which rarely takes place when the epidermis
is whole, but which uniformly does, when this being removed, the
matter is found in contact with the external capillary net-work of
which we have spoken. I would remark even that the different kinds of
inoculation of the small-pox, of the vaccine disease, &c. evidently
prove both the existence and importance of this net-work, to which
heretofore sufficient attention has not been paid. There are many
contagious principles which are absorbed through the epidermis; such
are those of the plague which the clothes communicate and those of
different pestilential fevers which penetrate by the skin more than by
respiration. I believe cutaneous absorptions from which diseases arise
may be divided in the following way:
{1st, local, as the itch, herpes,
1st. Absorptions which take place { tinea capitis, &c. &c.
through the epidermis, and which {2d, general, as pestilential
produce an effect { diseases, putrid fevers taken
{ in an unhealthy place, &c. &c.
{1st, local, as the vaccine
2d. Absorptions which take place { disease, the small-pox, &c. &c.
only when the epidermis is removed,{2d, general, as hydrophobia, the
and from which arises { venom of the viper, a wound
an effect { with an instrument impregnated
{ with putrid matter, &c. &c.
We see by this table that the absorbents when charged with injurious
substances, sometimes do not transmit them beyond the part and
sometimes carry them to the blood, which conveys them to the different
organs of the economy. Some authors have thought that in those cases
in which the effects of the absorption become general, there is rather
nervous action and sympathetic phenomena, than the transmission of
an injurious matter into the circulation, and that consequently the
solids take almost an exclusive part in these diseases. But to remove
all doubt upon this point it is sufficient to observe, 1st, that, in
the absorption of many contagious substances, for example, when from
the puncture of the finger with a scalpel impregnated with putrid
substances, a pain is produced, there is even a redness along the whole
course of the absorbents of the arm, and the axillary glands afterwards
swell; 2d, that by transfusing into the veins most of the substances
that are applied in frictions, effects analogous to those which take
place in these frictions are produced. Thus purgatives and emetics,
transfused or absorbed, act upon the intestines and stomach the same
as if introduced in any other way. It seems to me that sufficient use
has not been made of the experiments of the last age upon transfusions.
By comparing their effect with that which takes place upon the
cutaneous organ, I think that it is impossible not to admit a morbific
principle in the blood, at the time of contagious diseases.
3d. After the use of mercury taken in frictions, the emanations of this
metal from the animal fluids, act evidently upon silver when placed in
the mouth, the rectum, &c. I am persuaded even that the blood which
in the natural state exerts but very little action upon this metal,
would alter it then. Accoucheurs know that the waters of the amnios of
those women who have made use of mercurial frictions exhibit the same
phenomenon.
4th. Many substances that are not medicinal can be transmitted to the
blood by cutaneous absorption. Water appears to enter it in this way,
in the rapid production of certain dropsies, in those cases related of
travellers, who wanting fresh water on the ocean, have in part quenched
their thirst by surrounding themselves with damp clothes, &c. When our
garments are impregnated with the oil of turpentine, the urine soon
acquires an odour that is owing to the principles transmitted to the
blood by absorption. Many judicious philosophers have asserted that the
weight of the body has been increased by a walk in the morning.
I have observed that after remaining in the dissecting room some time,
the intestinal flatus frequently acquires an odour exactly similar to
that which the bodies in putrefaction exhale. In the following way
I convinced myself that it was the skin as much as the lungs that
absorbed these odorous particles. I closed my nostrils, and fitted
a long tunnel to my mouth, which passing out of the window allowed
me to breathe the external air. The flatus from my bowels, after I
had remained an hour in a small dissecting room, at the side of two
very fetid bodies, acquired an odour nearly similar to theirs. I have
observed also that by touching for a long time fetid substances, the
flatus acquires more of this odour, than by remaining only in an air
loaded with cadaverous exhalations. Then the absorbents carry at first
these exhalations to the blood, which afterwards throws them out by the
mucous surface of the intestines. Thus when the urine is absorbed, the
saliva, the mucous juices, &c. have an urinous odour.
I could accumulate many other proofs of cutaneous absorption; but I
have selected only the principal. Many others have been cited; Haller
in particular, to whom I refer, has multiplied examples of it.
I would remark however that cutaneous absorptions have a character
of remarkable irregularity; that under the same apparent influence,
they sometimes take place and sometimes do not. It is thus that most
often we absorb nothing in a bath, that we escape or take contagions,
that the vaccine disease is or is not communicated, that the variolous
inoculation is also often uncertain, &c. This is not astonishing. It
requires a certain degree of sensibility in the skin for the absorption
of this or that substance; above or below this degree, the absorbents
repel this substance. Thus in the intestinal canal, if you raise by a
purgative, the ordinary degree of sensibility of the lacteals, they
cease immediately for a time to take up drinks, chyle, &c. and every
thing passes off by the anus. Now a thousand causes act incessantly
upon the skin; a thousand irritants by turns applied to it make the
degree of its organic sensibility vary every instant, increase,
diminish and remove it from that which is necessary for absorption.
Is it astonishing then that this function should exhibit so many
varieties? Many modern philosophers have produced numerous negative
facts against cutaneous absorption. What do these facts prove? only
the varieties of sensibility which I have noticed; but they do not
destroy the mass of positive facts, generally acknowledged and which
together form a body of proof which nothing can oppose. Thus we have
seen the mucous surfaces variable in their vital forces on account
of the variety of their excitants, vary also in their absorption.
If in the serous membranes, in the cellular texture, in the work of
nutrition for the organs, this function is uniform, it is because being
constantly in contact with the same bodies, the surfaces where it is
going on have an uniform degree of organic sensibility.
Many facts, in relation especially to contagions seem to prove that a
state of weakness is favourable to cutaneous absorption. 1st. Children
and women absorb more easily than strong and vigorous men. 2d. Many
physicians have observed that in the night in which the cutaneous organ
is in a state of remission in this respect, as it is not stimulated
by external objects, contagious diseases are more easily taken. 3d. I
have remarked that most of the pupils who have fallen sick during my
dissections, had carried to their chambers portions of subjects, the
emanations from which had been able to affect them during sleep. 4th.
We know that practitioners recommend, that persons should not expose
themselves to contagious miasmata during hunger, as the forces are then
languid on account of the emptiness of the stomach.
_Exhalants._
The external capillary system which surrounds the chorion and embraces
the papillæ, appears to be the origin of these vessels, as it is the
termination of the arteries of the dermoid spaces. The exhalants take
up their fluid there, which they throw out upon the epidermis. We have
no anatomical knowledge as to their form, their length, their course
and their direction; but their existence is incontestibly proved, 1st,
by injections, which are sometimes poured out upon the whole cutaneous
surface; 2d, by the sanguineous exhalation which takes place in some
diseases in which there is a real bloody sweat; 3d, by the natural
sweat and by transpiration, which can evidently have no other agents,
though some authors have admitted that there were certain pretended
glands for the secretion of these fluids.
An infinite number of calculations has been made to ascertain the
quantity of fluid which the cutaneous exhalants usually pour out.
We are dismayed when we read the result of the labours of many
philosophers upon this point, when we go over the calculations,
enormously multiplied, of Dodard, Sanctorius, Keil, Robinson, Roye, &c.
To what do all these calculations, for which the life of a single man
would perhaps be insufficient, tend? To prove to us that when we start
from a false principle, the whole chain of consequences drawn from it
is false, though these consequences may be rigorously deduced from each
other. In fact, most philosophers have considered the skin as a kind of
fountain with numerous capillary tubes, always throwing out in the same
time the same quantity of fluids, and being able consequently to be
subjected, like inert capillaries which pour out fluids, to proportions
and calculations of quantity. But the results of these calculations
have soon proved how mistaken their authors were. Read these results,
and you will see that none of them agree, that frequently very great
differences characterize them. Is this astonishing? A thousand causes
make the transpiration vary at every instant. Temperament, exercise,
rest, digestion, sleep, watchfulness, the passions, &c. increase or
diminish the action of the cutaneous exhalants. I do not speak of the
difference from climate, seasons, &c. which is still more decided.
An attempt has even been made recently to ascertain, what belongs to
the urine, to the transpiration, to the pulmonary perspiration and
to the excrements, to calculate the relation which exists between the
quantities thrown out in these four ways; useless researches! We might
obtain from them results for one man, which would not be applicable
to others. Thus see if we have ever been able to make a single useful
application to physiology or pathology of all these immense labours
on transpiration. What would you say of a man who, during the days of
the equinox, in which the state of the atmosphere was every minute
changing, should try to establish proportions between the quantities of
rain which fell in every quarter of an hour, or of one who endeavoured
to fix relations between the quantities of fluids which are evaporated
in given times, from the surface of a vessel under which the intensity
of the heat which warmed the water varied every instant. The comparison
is just. We might be able to say in general, at the end of a given
time, nearly how many pounds of substances went from the body; and yet
this varies in every individual. But to attempt to say in a general
manner what, in this common quantity, the urine and transpiration
separately furnish, is to prove that we do not understand the nature of
the vital forces.
We have already observed, that all our knowledge upon the varieties of
transpiration, is reduced to some general data; that, for example, in
cold seasons and climates, it is by the internal emunctories that the
residue of nutrition and digestion principally passes off, whilst in
warm climates and seasons, it is the cutaneous organ that principally
throws it out.
The skin on the one hand, and the kidneys and pulmonary surface on the
other, are then in this respect, in a constantly inverse activity.
Physicians very well know this difference in regard to the urine and
sweat; they know that when one is increased, the other is diminished:
that in winter the urine contains principles of various kinds, and
that in summer the transpiration has a salt taste and other peculiar
characters which it owes to the substances which are foreign to it
in the first season. But they have not so well examined the relation
of the transpiration with the sweat; this determined me to make the
following experiments:
I wished to know what is the state of the respiratory fluid in
summer, in which there is much transpiration, and in which all the
heterogeneous principles consequently go out by the skin. To obtain
this fluid which is exhaled in insensible vapour, I placed a clean,
empty bottle in a pail filled with ice and the muriate of soda, and
I respired a long time in it, taking care not to allow any saliva to
fall in. The parietes, chilled by the external ice, condensed into
small icicles the vapour of my breath, on the internal surface of the
vessel. When I had made a certain quantity of these, I withdrew the
bottle; then by putting it into tepid water, the icicles immediately
melted, and I had in a liquid state my respiration, which was before
in vapour. Now I have been struck with two things in this experiment,
1st, with the small quantity of fluid that I was able to obtain, though
I had respired for an hour, and afterwards made two men respire each
an hour; 2d, with this, that most of the reagents have no action upon
this fluid. Nitric, sulphuric and muriatic acids, lapis infernalis,
and alkohol produce no effect when mixed with it. In evaporating a
small quantity in the concavity of a watch chrystal, no residuum is
left; placed in a spoon over the flame of a candle, it experiences no
alteration from the heat. In a word, I have been almost tempted to
believe that it was nothing but water. I confess however that this
experiment ought to be carefully repeated.
The little fluid obtained made me believe that the form of the vessel
was not well adapted to the purpose, because it did not present
sufficient surface and the vapour of the lungs was too little divided.
I took then the spiral cylinder of a small alembic which I surrounded
with ice in a pail; I made a man breathe through it, and I obtained
in fact more fluid, but infinitely less however than I expected,
considering the great cloud that is formed in winter by respiration.
In an hour, two ounces of fluid only were condensed, which I weighed
comparatively with water, and found a little heavier, a proof that some
principles are mixed with its aqueous portion, and with which I am
unacquainted.