dispel, according to some, the morbific humour, and overcome, according
to others, a natural irritation by an artificial one. Why should we
not also in many cases irritate the mucous surfaces? why not act upon
the pituitary membrane, upon the glans penis, upon the membrane of the
urethra, upon the pharynx, &c. and especially upon the uvula which is
so sensible? why, instead of epispastics upon the perineum and sacrum,
should we not introduce a sound into the urethra for a paralysis of the
bladder? Instead of acting in hemiplegia upon the cutaneous organ, I
have already twice employed the following means; I have introduced a
sound into the urethra, one in each nasal fossa, and at the same time,
a surgeon irritated at intervals the uvula; the patients appeared to be
much more excited than by blisters. Very strong purgative enemas and
emetics prove the advantage of the excitement of the mucous membranes
in this case. Would it not often be better in ophthalmia, to produce
an artificial catarrh in the nostril of the diseased side, than to
put a blister or seton in the neck? I have once tried it; it did not
succeed; but the ophthalmia was of long standing; I propose to repeat
these experiments at the Hôtel Dieu upon a great number of patients. I
think that we might often in diseases make use of mucous excitements
instead of cutaneous, with much more advantage, because in the mucous
system the contact of a body is sufficient, and it is not necessary to
produce, by removing the epidermis, a kind of ulcer.
The mucous membranes by the continual secretion of which they are
the seat, enjoy a principal part in the animal economy. We ought to
consider them as one of the great emunctories by which the residue of
nutrition constantly escapes, and consequently as one of the principal
agents of the habitual decomposition which removes from living bodies
the particles that, having for some time contributed to the composition
of the solids, are afterwards to become heterogeneous to them. Observe
in fact that the mucous fluids do not enter the circulation, but go out
of the body; that of the bladder, the ureters and the urethra, with
the urine; that of the vesiculæ seminales and the different ducts with
the semen; that of the nostrils by the act of blowing the nose; that
of the mouth, in part by evaporation and in part by the anus with the
excrements; that of the bronchia, by pulmonary exhalation, which arises
principally, as I shall say, from the solution of this mucous fluid in
the inspired air; those of the œsophagus, the stomach, the intestines,
the gall-bladder, &c. with the excrements, of which they often form
in the ordinary state a part almost as considerable as the residue
of the aliments, and which they even compose almost entirely in some
cases of dysentery and fever, in which the quantity of matter voided
is evidently disproportioned to that taken in, &c. Let us observe upon
this subject that there are always some errors in the analyses of the
fluids in contact with the membranes of which we are speaking, as in
that of the urine, the bile, the gastric juices, &c. because it is very
difficult and even impossible to separate the mucous fluids from them.
If we recollect what has been previously said upon the extent of the
two general mucous surfaces, which is equal and even superior to the
extent of the cutaneous organ, and if we afterwards consider that
these two great surfaces are constantly throwing out mucous fluids, we
shall perceive how important this evacuation must be in the economy,
and of what mischief its derangement must become the source. It is
undoubtedly to this law of nature which wishes to have every mucous
fluid thrown out, that must be attributed, in part in the fœtus, the
presence of the unctuous fluid of which the gall-bladder is full, the
meconium which loads the intestines, &c. fluids which appear to be but
a mass of mucous juices, which being unable to pass off, remain until
birth, without being absorbed, upon the respective organs on which they
have been secreted.
The mucous fluids are not the only ones that are thrown out, and are
in this way excrementitious substances to the economy; this is the
case with almost all the fluids separated from the mass of blood by
secretion; this is evident as it respects the greatest part of the
bile; probably the saliva, the pancreatic juice and the tears are
also thrown out with the excrements, and their colour alone prevents
them from being distinguished like the bile. I do not even know if,
by reflecting on many phenomena, we might not attempt to establish as
a general principle, that every fluid separated by secretion does not
enter the circulation again, that this phenomenon belongs only to the
fluids separated by exhalation, as those of the serous cavities, of the
articulations, of the cellular texture, of the medullary organ, &c.;
that all the fluids are thus either excrementitious or recrementitious,
and that no one is excremento recrementitious as the common division
implies. The bile in the gall-bladder, the urine in the bladder, the
semen in the vesiculæ seminales, are certainly absorbed; but it is not
the fluid itself which re-enters the circulation; it is only its most
delicate parts, some of its principles which we do not exactly know,
probably the serous and lymphatic part; this does not resemble the
absorption of the pleura and other analogous membranes, in which the
fluid re-enters the blood as it came out of it.
That which is certain on the subject of the excretion of the secreted
fluids is, that I have never been able to produce absorption of the
bile by the lymphatics by injecting it into the cellular texture of
an animal; it produces there inflammation and afterwards suppuration.
We know that urine effused is not absorbed and that it destroys every
part it touches, whilst that effusions of lymph and blood are easily
discussed. There is as it respects the composition an essential
difference between the blood and the secreted fluids. The exhaled
fluids on the contrary, as the serum, in this respect resemble it very
much.
Another very evident proof that all the mucous fluids are designed to
be thrown out, is, that when they have continued for some time in any
quantity upon their respective surfaces, they create there a painful
sensation of which nature relieves us by various means. Thus the
cough, which is the constant result of an accumulation of mucus in the
bronchia, serves to expel it; thus vomiting in gastric derangements
answers the same purpose as it respects the mucous juices accumulated
in the stomach, whose presence produces a weight and even pain, though
the membranes be not affected. We cough at will, because it is the
diaphragm and intercostals by which this function is performed; we do
not seek in medicine for any means to excite it. But as we cannot vomit
at will, and as the presence of mucous juices often by fatiguing the
stomach, does not irritate it sufficiently to produce a contraction,
art has recourse to various emetics. We know what a painful sensation
of weight the continuance of mucus accumulated in the frontal,
maxillary, sinuses, &c. occasions, when there is a catarrh of a portion
of the pituitary membrane. The region of the bladder is for the same
reason, in catarrhs of this organ, the seat of a troublesome and even
painful sensation.
In general, the sensation which arises from the presence of the
mucous juices remaining too long and in too great quantity upon their
respective surfaces, varies because, as we shall see, each part of
the mucous system has its peculiar mode of sensibility; so that the
pain is not the same in each, though produced by the same cause. I
would only observe that this sensation does not resemble that which
arises from the tearing or the acute irritation of our parts; it is an
uneasy, inconvenient sensation, difficult to be borne. Every one knows
that which arises from mucus accumulated in the nasal fossæ, when the
nose has not been blown for a long time, that disagreeable one that
accompanies gastric derangements, &c. Those who have a weakness of
the lachrymal sac in which the tears, on account of this, accumulate
during the night, wake up with a sensation of weight, of which they are
relieved by evacuating the sac by pressure, if the puncta lachrymalia
are open.
_Blood Vessels._
The mucous membranes receive a very great number of vessels. The
remarkable redness that distinguishes them would be sufficient to
prove it, if injections did not demonstrate it; this redness is not
everywhere uniform. It is almost nothing in the sinuses of the face, in
the internal ear, of which the membranes are rather whitish, and which
appear so especially, because their extreme delicacy allows the bone
upon which they are applied to be seen very distinctly. In the bladder,
in the great intestines, in the excretories, &c. this colour, though
still very pale, is a little more evident; it becomes very much so in
the stomach, the small intestines, the vagina and in the pituitary and
palatine membranes. In the gall-bladder we cannot distinguish it,
because the bile always covers the mucous surface in the dead body.
This colour depends upon a very extensive vascular net-work, the
branches of which, after having passed through the mucous corion,
and ramifying there, divide and spread ad infinitum on its surface,
embracing the papillary body and covered only by the epidermis.
It is the superficial position of these vessels and consequently
their want of support on one side, that exposes them frequently to
ruptures from considerable shocks, as happens on the surface of the
bronchia from a severe cough, on that of the ear and the nose from a
violent blow on the head. We know that hemorrhage of the mucous system
bordering on the brain, is a common accident from concussions and
wounds of the head. Hence why the least gravel makes the ureters bleed;
why one of the signs of stone in the bladder is the passing of blood;
why a blunt sound carefully introduced is so often withdrawn bloody
from the urethra; why the least effort made with instruments carried
upon polypi, into a fistula lachrymalis or into the nostrils, produces
hemorrhage. I have already observed that we must carefully distinguish
these hemorrhages from those furnished by the exhalants, and which do
not suppose any vascular rupture.
It is also the superficial position of the vessels of the mucous
system, which makes its portions visible, as the red edge of the
lips, the glans penis, &c. often serve to show us the state of the
circulation. Thus in the different species of asphyxia, in submersion,
strangulation, &c. these parts are remarkably livid, an effect of the
passage of the venous blood, which has undergone no change from the
want of respiration, into the extremities of the arterial system.
The long continued exposure of the mucous system to the air, often
makes it lose the redness that characterizes it, and it then
assumes the appearance of the skin, as has been observed by Sabatier
in treating of prolapsus of the womb and vagina, which, from this
circumstance, have sometimes so misled some people, as to make them
believe it a case of hermaphrodism.
An important question presents itself in the history of the vascular
system of the mucous membranes, viz. whether this system admits more
or less blood according to different circumstances. As the organs
within which these membranes are spread, are almost all susceptible of
contraction and dilatation, as we see in the stomach, the intestines,
the bladder, &c. it has been thought that during the dilatation, the
vessels being more expanded, receive more blood, and that during the
contraction on the contrary, being folded up, as it were choaked,
they admit but a small quantity of this fluid which then flows into
the neighbouring organs. Chaussier has made an application of these
principles to the stomach, whose circulation he has considered as being
alternately inverse of that of the omentum, which receives during the
vacuity of this organ, the blood which this when it is contracted
cannot admit. An analogous use has also been attributed to the spleen
since the time of Lieutaud. The following is what the inspection of
animals opened during abstinence and at different periods of digestion,
has shown me upon this point.
1st. During the fulness of the stomach the vessels are more apparent on
the exterior of this viscus, than when it is empty. Within, the mucous
surface is not more red, sometimes it has appeared to me to be less
so. 2d. The omentum, less extended during the fulness of the stomach,
exhibits nearly the same number of vessels, as long, but more tortuous,
than when it is empty. If they contain less blood, the difference is
hardly sensible. I would observe, that in order to distinguish this
well, it is necessary to take care that in opening the animal, the
blood does not fall on the omentum which presents itself, and thus
prevent its state from being ascertained. This is besides a necessary
consequence of the arrangement of the vascular system of the stomach.
In fact the great stomachic coronary being situated transversely
between it and the omentum, and furnishing branches to each, it is
evident that when the stomach is lodged between the layers of the
omentum by separating these layers, and this by applying itself upon
it becomes shorter; it is evident, I say, that the branches which it
receives from the coronary cannot be equally applied to it also. In
order to do this, it would be necessary that they should go from one
to the other without the intermediate trunk that cuts them at right
angles; then, in distending, the stomach would separate them as it
does the omentum, and would be lodged between them; whereas it pushes
them before it with their common trunk, the stomachic coronary, and
makes them fold. 3d. I am confident that there is no such constant
relation between the size of the spleen and the emptiness or fulness
of the stomach, and that these two circumstances coincide necessarily,
and that if the first organ increases or diminishes under different
circumstances, it is not always precisely the reverse of the stomach.
I first made, like Lieutaud, experiments upon dogs to convince myself
of it; but the inequality in the size and age of those that were
brought to me, making me fear that I should not be able to compare
their spleens correctly, I repeated them upon guinea-pigs of the same
litter and size, and examined at the same time, some when the stomach
was empty and others when it was full. I have almost always found the
size of the spleen nearly equal, or at least the difference was not
very sensible. Yet in other experiments, I have seen under various
circumstances, inequalities in the size of the spleen and especially
in the weight of this viscus; but it was indifferently during or after
digestion.
It appears from all this, that if during the vacuity of the stomach,
there is a reflux of blood towards the omentum and spleen, this reflux
is less than it has been commonly said to be. Besides during this
state of vacuity, the numerous folds of the mucous membrane of this
viscus leaving it, as we have said above, almost as much surface and
consequently as many vessels as during fulness, the blood can circulate
in it almost as freely. It has no real obstacles but in the tortuous
courses, and not in the obstruction, compression and choaking of these
vessels by the contraction of the stomach; now this obstacle is easily
surmounted, or rather it is not one as I have proved in my Researches
upon Death. As to the other hollow organs, it is difficult to examine
the circulation of the neighbouring parts during their fulness and
vacuity, as the vessels of these are not superficial as in the omentum,
and as they themselves are not insulated like the spleen. We can only
then, to decide the question, see the state of the mucous membranes on
their internal face; now this face has always appeared to me to be as
red during the contraction as during the dilatation.
Besides I only give this as a fact without pretending to draw from it
any consequence in opposition to the common opinion. It is possible in
fact that though the quantity of blood may be nearly always the same,
the rapidity of the circulation being increased, more of this fluid may
consequently in a given time enter it when it is full; which appears
to be necessary to the greater secretion that then takes place of the
mucous fluids, a secretion excited by the presence of the substances in
contact with the surfaces of the same name. For example, there is no
doubt that there is three or even four times as much mucus secreted in
the urethra, when a sound fills it, as when it is empty; now the blood
must be in proportion.
The remarkable redness of the mucous system, the analogy of respiration
in which the blood flows through the mucous surface of the bronchia
the well known experiment of a bladder filled with blood and immersed
in oxygen, by which means the blood becomes red, have induced a belief
that the blood being separated from the atmospheric air only by a thin
pellicle or some of the mucous surfaces, as upon the pituitary, the
palatine, the glans penis, &c. assumed there a redder colour, either
from getting rid of a portion of its carbonic acid gas, or by combining
with the oxygen of the air, and that these membranes thus performed
functions accessory to those of the lungs. The experiments of Jurine
upon the cutaneous organ, experiments adopted by many celebrated
philosophers, seem to strengthen this conjecture.
I tried the following experiment to ascertain this fact. I drew through
a wound made in the abdomen a portion of intestine which I tied at one
point, I afterwards reduced it, keeping out a small portion only which
I opened and by which I introduced atmospheric air, which filled the
whole portion situated on this side of the ligature. I afterwards tied
the intestine below the opening, and reduced the whole of it. At the
end of an hour, the animal being opened, I compared the blood of the
mesenteric veins which arose from the portion of intestine distended
with air, with the blood of the other mesenteric veins arising from the
rest of the canal. No difference of colour was manifest; the internal
surface of the distended portion of the intestine was not of a more
brilliant red. I thought I should obtain a more evident effect, by
repeating with oxygen the same experiment upon another animal; but I
perceived no greater variety in the colour of the blood. As upon the
mucous membranes which are ordinarily in contact with the air, this
fluid is constantly changing and is agitated by a perpetual motion,
and as in the preceding experiment it remained stagnant, I attempted
to produce the same effect in the intestines. I made two openings in
the abdomen, and drew out at each a portion of the intestinal canal;
having opened these two portions, I fitted to one the tube of a bladder
full of oxygen and to the other that of an empty bladder; I afterwards
compressed the full bladder, so as to make the oxygen pass into the
other, by going through this portion of intestine, left in the abdomen
that the heat might support the circulation in it. The oxygen was
thus many times sent from one bladder to another, taking its course
through the intestine, which, on account of its contractility is more
difficult than it at first seems to be. The abdomen being afterwards
opened I found no difference between the venous blood returning from
this portion of intestine, and that which flowed from the others. The
superficial position of the mesenteric veins, covered only by a fine
and transparent layer of peritoneum, their size, if the animal be
rather large, render this sort of comparison very easy.
I perceive that we cannot infer from what takes place in the
intestines, what happens in the pituitary, palatine membrane, &c.
because though analogous, the organization may be different. We cannot
here as in the intestines examine the venous blood returning from the
part; but, 1st, if we consider that in animals who have respired oxygen
for some time, we see the palatine and pituitary membranes more red;
2d, if we reflect that the lividity of the different parts of this
membrane, in those destroyed by asphyxia by the carbonic acid gas,
depends not on the immediate contact of this gas upon the membrane,
but upon the passage of venous blood into the arterial system, as my
experiments have, I think, demonstrated; 3d, if we remark finally
that in these circumstances the contact of the air does not change,
after death, the lividity which the venous blood gives to the mucous
membranes, although the skin be then much more permeable to every
kind of aeriform fluid; we shall see that it is at least necessary to
suspend our judgment upon the colouring of the blood in the mucous
membranes, until further observations have decided the question.
The following experiment may also throw some light upon the subject.
I have inflated the peritoneal cavity of several guinea-pigs with
carbonic acid gas, with hydrogen, oxygen and atmospheric air, to see if
I could effect through a serous membrane what I could not make succeed
in a mucous; I have not, after these experiments, found any difference
in the colour of the blood of the abdominal system; it was always the
same as in the common guinea-pig which I killed for comparison.
I think however that I have remarked many times, both in frogs and
animals with red and warm blood, such as cats and guinea-pigs, that
the infiltration of oxygen into the cellular texture gives, at the end
of some time, a much brighter colour to the blood, than that which
this fluid exhibits in artificial emphysemas produced by carbonic
acid gas, hydrogen and atmospheric air, in all which the colour of
the blood scarcely differs at all from what is natural. But in other
cases oxygen has had no influence upon the colour of the blood; so
that notwithstanding having made many experiments upon this point, I
am unable to give any general result. It appears that the tonic forces
of the cellular texture and of the parietes of the vessels which are
spread upon this texture, receive a very variable influence from
the contact of the gases, and that according to the nature of this
influence, the fibres crisping and contracting more or less, render
these parts more or less permeable, either to the aeriform fluids
that tend to escape from the blood in order to unite with that of the
emphysema, or to this last fluid, if it tends to combine with the
blood, which no doubt produces the varieties I have observed.
The red colour of the mucous system is analogous to that of the
muscular system. It does not depend essentially on the blood
circulating in the small arteries of this system. It arises from
the colouring portion of the blood combined with the mucous texture,
especially in the deep part of the organs; for at the origin of the
mucous surfaces, this colour appears to be principally owing to the
blood in circulation; in fact asphyxia does not render so livid the
deep mucous surfaces, as it does those which are superficial and in
communication with the skin. The black blood arrives immediately to
these by the last arteries, and tinges them as we see. In syncope in
which the heart being affected no longer sends blood into the arteries,
we know that this portion of the mucous system becomes instantly white.
Besides the red colour of the deeper portions, can, like that of the
muscles, be removed by repeated washing and frequently changing the
water. Yet the water in which they have been washed is not as red as
that used for the muscles.
The instant a mucous surface is plunged into boiling water, however
red it may be, as that of the intestines and the stomach, it instantly
whitens. The action of the nitric, sulphuric and muriatic acids
produces in it also a sudden whiteness.
This colour of the mucous surfaces acquires a remarkable intensity in
inflammation. The redness becomes then extremely deep on account of the
quantity of blood that is accumulated in the capillary system. It is
particularly in dysentery that the internal surface of the intestines
exhibits this phenomenon in a striking degree. I ought however to
observe to those who open dead bodies, that they never should lose
sight of the original tinge of the portion of the mucous system they
examine, since each of the divisions of this system exhibits in its
shades remarkable differences. If the membrane of the bladder, the
rectum, &c. is found as red as that of the stomach in its natural
state, then pronounce that there had been inflammation; if the redness
of the sinuses equals that which is natural to the bladder and the
rectum, decide that inflammation had existed in them. There is, as
I have said, a scale of colour for the mucous system. It is then
essential to have an accurate knowledge of this scale, a type to which
we can refer the inflammatory state in the examination of dead bodies.
_Exhalants._
Does exhalation take place upon the mucous surfaces? The analogy of the
skin seems to indicate it; for it is well proved that the sweat is not
a transudation through the inorganic pores of the cutaneous surface,
but a real transmission by vessels of a peculiar nature and continuous
with the arterial system.