All that has been said evidently supposes a free communication
established between all the parts of the capillary system; this
communication is in fact clearly demonstrated by observation. When we
examine a serous injected surface, of which the capillary system is
full, we see that this system is a real net-work with fine meshes, and
in which no vessel runs a distance of more than two lines, without
communicating with others. The passage then, is constantly open between
the portion that receives blood, and that which admits fluids differing
from it. The same arrangement exists in the dermoid system, in the
origins of the mucous, &c. and in general in all those in which the
capillary system contains blood and white fluids.
On the other hand, the organs in which we find only white fluids,
evidently communicate with those that are near them, and in which there
is blood; those in which blood alone flows, have the same arrangement.
The capillary system must then be considered as a general net-work,
spread throughout the body, which communicates on one side in every
organ, and on the other from one organ to another. In this respect
there is from the head to the feet a general anastomosis, a free
communication for the fluids. It is in this way that we can conceive
of the permeability of the body, and not from the cellular texture, in
which the serous and fatty fluids alone stagnate.
As the arteries enter the capillary system, and as the veins, the
exhalants, the secretories, go from it, it is evident from this manner
of considering the capillary system, that all these vessels ought to
communicate with each other; that by pushing a fine fluid into the
arteries, it should go out by the excretories, the exhalants, and
return by the veins, after having gone through the capillary system;
this is in fact what takes place. In this respect, a thousand ways
are constantly open for the blood to escape from its vessels, which
communicate thus everywhere without, and do not present any mechanical
obstacle to the blood in their cavity, which life alone retains within
the limits of its circulation. The oozings after death through the
exhalants, the excretories and the veins, are so well known, so many
anatomists have related examples of them, that I think it unnecessary
to give them in detail here. We have seen, then, fine injections pour
out upon the serous membranes, upon the pericardium, the pleura, the
peritoneum, &c. transude upon the mucous surfaces, even upon the skin.
We have seen them flow through the ureters, the pancreatic, biliary,
salivary ducts, &c. Haller, in the article upon each organ, has not
failed to relate examples of this sort, which prove the communication
of the arteries with all the other vessels, by means of the capillary
net-work. What anatomist has not sometimes made even coarse injections
return by the veins? The communication of these vessels with the
arteries, through the capillary system, is now an anatomical axiom. At
one time, it arrested much attention. It has been asked, if there was
any thing intermediate between the arteries and the veins; inspection
proves that the capillary system alone is there.
Hence it is necessary to represent the capillary system as a kind
of general reservoir, in which the arteries enter on one side, and
from which go out on the other side, in all the organs, the nutritive
exhalants, in some, certain particular exhalants, as those of the
sweat, the lymph, the fat, &c. in others the secretory vessels, &c. It
is a common reservoir, if I may so express myself, in which the red
blood enters, and from which the black blood, the exhaled, the secreted
fluids, &c. go out.
This idea is not hypothetical; the injections of which I have spoken
are the most evident proof of it. Let it not be said that it is a
transudation after death, analogous to that of the bile through the
gall-bladder: if it were so, not only the fine fluids injected would
go out by the excretories and the exhalants, and return by the veins;
but in oozing through the pores, they would fill the whole cellular
texture. On the contrary, nothing escapes into the cellular texture,
around the vessels by which the injection passes; there is then a
continuity of tubes from the artery which has received the fluid, to
the excretory, the exhalant, or the vein which transmits it.
These are the communications of the capillary system that explain
how the skin becomes livid on the place on which a dead body has
for a long time lain, as on the back, for example; how by turning a
dead body, so that the head may hang down, it becomes full of fluid;
how, on the contrary, by placing upright the body of one dead from
apoplexy, asphyxia, &c. the capillary system of the face is freed
in a great measure from the blood it contained; how an erysipelas
disappears on a dead body, when the blood, arrested during life on a
part of the skin, by the vital action, is spread after death to all the
surrounding parts; how every kind of analogous redness of the skin,
and even of the serous surfaces, disappears because the blood goes by
the communications of the capillary system to the neighbouring organs.
During life the tonic action retains the fluid in a determinate part;
abandoned to its gravity, and other physical causes, after death, it
soon disappears from the part in which it was accumulated, on account
of the innumerable communications of the general capillary system.
I would observe to those who examine dead bodies, that these
considerations are very important. Thus we must not judge of the
quantity of blood which penetrated the inflamed peritoneum or pleura,
by what is seen twenty-four hours after death; local irritation was a
permanent cause that fixed the blood in the part; this cause having
ceased, it escapes from it. A serous membrane may have been very much
inflamed during life, and yet exhibit almost its natural appearance
after death; as it is in erysipelas. I should have been often tempted
from opening dead bodies, to deny the existence of an affection which
had been real. The same remark applies to the inflamed cellular
texture, the mucous surfaces, &c. Examine a subject that has died of
angina, which during life gave the deepest red colour to the pillars of
the velum pendulum pelati, to the velum itself and the whole pharynx;
after death, the parts assume nearly their natural colour.
I would observe that in this respect it is necessary to distinguish
acute from chronic affections. In the chronic inflammations, for
example, of the pleura, of the peritoneum, &c. the redness continues
after death, because the blood is combined, as it were, with the organ;
it makes a part of it, as it makes a part of the muscles in a natural
state. So the chronic affections of the skin, of the mucous surfaces,
retain after death nearly the same blood, that they had during
life; whereas in acute affections, the blood retained for a time by
irritation, escapes when life has ceased, upon which this irritation
depended. These principles can be applied to many diseases; I repeat
it, they are of great importance in examining bodies. The neglect of
them has often led me into an error, upon the degree and even the
existence of acute inflammations, of which the organs that I examined
had been the seat.
V. _How, notwithstanding the general communication of the Capillary
System, the Blood and the Fluids differing from it, remain separate._
Since in the dead body, and consequently during life, there is in
the capillary system no organic obstacle to the communication of the
fluids through its small branches; since the general net-work that
these vessels form is everywhere free, how does it happen that the
blood does not pass into the part destined to the white fluids? how
is it that these do not enter where the blood is to circulate? Why
does not this fluid go out by the exhalants and the excretories, since
these tubes communicate with the arteries by the anastomoses of the
capillary system? This depends wholly upon the relation which exists
between the organic sensibility of each part of the capillary system,
and the fluid that it contains. That which carries the blood, finds in
all the other fluids irritants that make it contract at their approach;
and reciprocally, where the other fluids belong, the blood would be a
foreign fluid. Why does the trachea admit air, and reject every other
fluid? Why do the lacteals choose only chyle from the contents of the
intestines? Why does the skin absorb certain substances, and repel
others, &c.? It all depends upon this, that each part, each portion of
an organ, every organic particle, has its own sensibility, which is in
relation only with one substance, and repels others.
But as this kind of sensibility is remarkably subject to vary, its
relation to substances foreign to the organ changes also; thus the part
of the capillary system which rejected blood, admits it at the moment
when its sensibility has been increased. Irritate a part of the skin,
it reddens in an instant; the blood flows there; while the irritation
continues, it remains; when it ceases, it disappears. Whatever be the
external means which raise the cutaneous or mucous sensibility, we
observe the same phenomenon. We can in this way bring more or less
blood into some parts of the capillary system. Bring the hand to the
fire, the heat exalts the sensibility of its system, more blood enters
it; take it away, this property resumes its natural type, and the blood
is brought back to its ordinary quantity. The internal organs which
are subjected less to the causes of excitement, have less varieties in
their capillary system; yet, however, there are many, and all arise
from the same principle.
A series of organized tubes are unlike an assemblage of inert ones.
These last require mechanical obstacles to prevent the communication
of fluids with each other; where there is a communication between the
tubes, there is a communication in the fluids. On the contrary, in the
living economy, it is the peculiar vitality with which each tube is
animated, which serves for an obstacle and a limit to the different
fluids; this vitality performs the part of different machines that we
place in the communicating tubes, to separate them from each other.
Every organized vessel is then truly active; it admits or rejects
fluids which enter there, according as it is able or not to support
their presence. Disproportion of capacity has nothing to do with this
phenomenon; a vessel may have mere than four times the capacity of
the particles of a fluid, and yet refuse to admit them, if this fluid
is repugnant to its sensibility. It is in this point of view that the
theory of Boerhaave has a great defect.
At the period in which this physician wrote, the vital forces had not
been analyzed. It was necessary to employ physical forces to explain
vital phenomena; hence it is not astonishing that all his theories
are so incoherent. In fact, theories in the vital phenomena borrowed
from physical forces, exhibit the same inadequacy, as those would in
the physical phenomena borrowed from vital laws. What would you say,
if in explaining the motion of the planets, rivers, &c. they should
talk of irritability and sensibility? you would think it absurd; it is
equally absurd, in explaining the animal functions, to talk of gravity,
impulse, inequality of the capacity of the tubes, &c.
Observe, that the physical sciences made no progress until they
analyzed the simple laws that preside over their innumerable phenomena.
Observe also, that medical and physiological science was not accurately
explained, until the vital laws were analyzed, and it was shown
that they were everywhere the principles of the phenomena. See with
what ease all those of the secretions, exhalations, absorptions,
inflammation, capillary circulation, &c. are referred to the same
principles, flow from the same data, by deriving them all from their
real cause, the different modifications of the sensibility of the
organs which execute them. On the contrary, see how each presented a
new difficulty, when the mechanical causes were employed to explain
them.
From what has been said, it is then evident, that in the innumerable
variations of which the fluids of the capillary system are susceptible,
in the different portions of the system which they fill, there is
always antecedent variations in the sensibility of the vascular
parietes; these varieties produce the first.
It is especially in the capillary system and its circulation, that the
variations of the organic sensibility of the vessels produce varieties
in the course of the fluids; for as I have observed, in the great
arterial and venous trunks, in the heart, &c. the fluids are in too
large masses, and they are agitated by too strong a motion, to be thus
immediately subjected to the influence of the vascular parietes. Thus
when nature wishes to prevent the fluids from communicating in the
trunks, it places among them valves, or other analogous obstacles,
which become useless in the capillary system.
Though the anatomical arrangement be the same in the living and the
dead body, there is then a very great difference in the course through
the capillary system, in one and the other. Push, into the aorta of
an animal in whom you destroy life by opening this artery to fix in
it a syringe, different fine fluids; you will never see them fill the
capillary system, pour out by the exhalants, the excretories, &c. as
when the subject has been some hours deprived of life. The organic
sensibility inherent in the parts repels the injection; it can only
circulate in the great trunks, in which there is a large space. I
have injected, with other views, a great number of times, fluids by
the arteries and the veins; now, the capillary system is never filled
with these fluids; they circulate only in the great vessels, when the
animal can bear them. Mr. Buniva has also made comparative experiments
with injections upon living animals and those deprived of life; he has
experienced in the first a resistance which he has not found in the
other; now this resistance is in the capillary system, whose vessels
refuse to admit a fluid to which their organic sensibility is not
accommodated.
VI. _Consequences of the preceding principles, in relation to
Inflammation._
From what has been said thus far, it is easy, I think, to understand
what takes place in the inflammatory phenomena, considered in general.
If a part be irritated in any manner, immediately its organic
sensibility is altered, and increased. Without previous connexion with
the blood, the capillary system is then placed in relation with it; it
as it were calls it there; it flows there and remains accumulated until
the organic sensibility returns to its natural type.
The entrance of the blood into the capillary system is then a secondary
effect of inflammation. The principal phenomenon, that which is the
cause of all the others, is the local irritation which has changed
the organic sensibility; now this local irritation may be produced in
different ways; 1st, by an irritant immediately applied, as a straw
upon the conjunctiva, cantharides upon the skin, acrid vapours upon
the mucous surface of the bronchia or the nasal cavities, atmospheric
air upon any internal organ laid bare, as we see in wounds, &c.; 2d,
by continuity of organs, as when a part of the skin, of the pleura,
&c. being inflamed, those that are near it are also affected, and the
blood flows there, as when one organ is diseased, that which is near it
becomes so by the cellular communications; 3d, by sympathies; thus the
skin being seized with cold, the pleura is sympathetically affected;
its organic sensibility is increased, the blood immediately enters it
from every part. When this property is raised in one of these three
ways in the capillary system, the phenomena that result from it are the
same. For example, when in the pleura it is raised because the air is
in contact with this membrane, because the lungs that it covers have
been first affected, or because coin has seized upon the skin in sweat,
the effect is nearly analogous, as it respects the entrance of the
blood in the capillary system.
It is then the change that takes place in the organic sensibility, that
constitutes the essence and the principle of the disease; it is this
change which makes a pain more or less severe soon felt in the part;
then the sensibility that was organic, becomes animal. The part was
before sensible to the impression of the blood, but did not transmit
this impression to the brain; then it transmits it, and this impression
becomes painful. Irritate the healthy pleura in a living animal; it
does not suffer; irritate it on the contrary during inflammation, and
it gives signs of the most acute pain. Who does not know that most
often and almost always, a pain more or less acute is perceived in the
part, some time before it becomes red? Now this pain is the indication
of the alteration that the organic sensibility undergoes; this
alteration exists some time, often without producing an effect; this
effect, which is especially the afflux of blood, is subsequent.
It is the same of heat. I shall say hereafter how it is produced. It is
sufficient now to show that it is, like the passage of the blood in the
capillary system, only an effect of the change that has taken place in
the organic sensibility of the part; now this is evident, since it is
always consequent upon this change.
There happens then in inflammation exactly the reverse of what
Boerhaave thought. The blood accumulated according to him, in the
capillary vessels, and pushed _à tergo_ by the heart, as he termed it,
was truly the immediate cause of the affection, whereas, from what I
have said, it is only the effect.
If we reflect a little upon the innumerable varieties of the causes
which can alter the organic sensibility of the capillary system, it
will be easy to understand of what infinite varieties inflammation
is susceptible, from the momentary blush that comes and goes in the
cheeks, to the most serious phlegmon and erysipelas. We might make a
scale of the degrees of inflammation. By taking the cutaneous, for
example, we should see at the bottom the redness that arises and
disappears suddenly by the least external excitement upon the dermoid
system, which we can produce at will, and in which there is only an
afflux of blood; then those that are a little more intense, which
occasion cutaneous efflorescences of some hours, but without fever;
then those that continue for a day, with which there is some fever;
then erysipelas of the first order; then that which is more intense,
and which gangrene soon terminates. All these different degrees do
not suppose a different nature in the disease; the principle of them
is always the same; there is always, 1st, an antecedent increase of
organic sensibility, or alteration of this property; 2d, afflux of
the blood only if the increase is not great, afflux of the blood,
heat, pulsation, &c. if it is. As to fever, it is a phenomenon common
to every severe, acute local affection; it appears to depend on the
singular relation which connects the heart with all parts; it has
nothing peculiar in inflammation, but the particular modification it
receives from it.
The afflux of the blood in an irritated part takes place in
inflammation, as in an incision. In this the divided point has been
irritated by the instrument; soon the whole blood in the neighbourhood
flows there and escapes by the wound. This afflux is so evident a
result of irritation, that in a slight incision, the blood scarcely
flows at the instant of the division of the integuments, because there
is but little of this fluid at the divided place; but a moment after,
the irritation which has been felt, produces its effect, and it flows
in a quantity disproportioned to the incision.
When the alteration of the organic sensibility which produces
inflammation, has no varieties except in its intensity, the
inflammation itself differs only in degree. But the nature of the
alteration is oftentimes different; a feeble character is frequently
united with it; the part has then less redness, heat, &c. Other
modifications are also observed; now all these depend upon the
difference of the alterations that the organic sensibility experiences;
at least these alterations always precede them.
The influence of these alterations is not less evident when
inflammation terminates, than when it begins. If the organic
sensibility has been so raised, that it is as it were exhausted,
then the solid dies, and the fluid, which is no longer in a living
organ, soon becomes putrid. Examine the phenomena of every gangrene;
putrefaction is certainly only a consequence; there is always, 1st,
a desertion of the solids by the vital forces; 2d, putrefaction of
the fluids. The first is never a consequence of the second. When the
organic sensibility begins to diminish, the blood brought there by
inflammation is already susceptible of putrefaction; but the defect of
tone in the solid always precedes. There is this local phenomenon, as
well as the general, in putrid fever. It is incontestable that in this
fever, the blood has a tendency to be decomposed, to become putrid; I
will say further, that it often exhibits a commencing putrefaction.
The index of the alteration of this fluid is always the general state
of the forces of the solids; these have first lost their spring;
the symptoms of weakness are evident before those of putridity. All
the animal fluids tend naturally to putrefaction, which takes place
inevitably when life abandons the solids in which they circulate. In
proportion as the forces diminish in the solids, this tendency is
manifested. A commencement of putrefaction in the fluids during life,
is not a general phenomenon more improbable than the local phenomenon
of which we have spoken, viz. that the blood of an inflamed part
begins to putrefy and the part consequently becomes fetid, before the
organic sensibility has entirely abandoned the solid. It is only when
this ceases, that this putrefaction becomes complete; but then it is
extremely rapid, because it had commenced during life. So bodies that
have died of putrid fevers decompose with a rapidity far surpassing
those that have died of other diseases, because putrefaction had really
commenced before death.
Inflammation with a livid colour, small degree of heat, prostration of
the forces in the part, and termination by gangrene, is evidently to
well marked adynamic fever, what phlegmon is to inflammatory fever,
what irritation of the primæ viæ, which is called bilious affection,
is to the meningo-gastric fever, &c. I think if we examine attentively
local affections and general fevers, we shall always find a particular
kind of fever corresponding in its nature to a particular kind of local
affection. But let us return to inflammation.
If it terminates by suppuration, it is evident that there is a new
alteration of the organic sensibility to produce pus. The same thing
in scirrhus. The termination by resolution takes place when this
sensibility returns to its natural type. Examine well the inflammatory
phenomena in their succession; you will see, that always a particular
state in this property, precedes the changes they exhibit.
When our medicaments are applied upon an inflamed part, it is not upon
the blood that they act; it is not by lessening the heat, or relaxing.
The expressions _to soften_, _unbend_ and _relax_ the solids, are
inaccurate, because they are borrowed from physical phenomena. We
relax, we soften dry leather by moistening it; but we only act upon
the living organs, by modifying their vital properties. Observe that
though we already begin to recognize the empire of these properties in
diseases, medical language is still wholly borrowed from theories which
employ physical principles in the explanation of morbid phenomena. We
have arrived at a period when the manner of expressing ourselves upon
these phenomena should be changed; I do not here speak of the names of
diseases. Certainly every emollient, astringent, discutient, relaxing,
tonic, medicament, &c. employed with different views upon an inflamed
part, only acts by modifying differently from what it was, organic
sensibility. It is thus that our medicaments cure or often aggravate
diseases.
From what has been said, it is evident that the solids perform the
first part in inflammations, and the fluids only the second. Modern
authors have perceived this truth, and they have immediately assigned
an important part, in this respect, to the nerves; but we have seen
that these appear foreign to organic sensibility, that they are so
even after the most rigorous observation. The nervous influence, that
at least which we know in other parts, is, in inflammation, as in
secretion, exhalation and nutrition, almost entirely wanting. There is
in this affection, unalteration of the organic sensibility, and this is
every thing.
The kind of blood varies in inflammation, and in this respect, I
think the following rule is generally uniform; whenever the organic
sensibility is much raised, the life augmented and there is an increase
of forces in the inflamed part, then it is the red blood that remains
in the capillary system; then there is always great heat there. On
the contrary, when the inflammation approaches the putrid character,
the part becomes of a dull and livid colour; the capillaries appear
to be filled with black blood; the heat is less. In general, a bright
colour, in all eruptions analogous to inflammatory tumours, announces
the increase of the organic sensibility. A livid colour, on the other
hand, indicates its prostration; petechiæ are livid; scorbutic blotches
are so; a livid colour in tumours is the forerunner of gangrene. Do you
wish to know when cold acts as a stimulant? It is when it reddens the
end of the nose, the ears, &c. When these parts become livid, other
phenomena announce at the same time, that its action is sedative. This
is supported by my experiments upon life and death, which have proved
that the black blood everywhere interrupts the functions, weakens,
annihilates even the motion of the parts, when it is brought to them by
the arteries.
_Differences of Inflammation, according to the different Systems._
From what has been said upon inflammation, it appears that it has for
its seat the capillary system, for its principle an alteration in
the organic sensibility of this system, for its effect the afflux of
blood into vessels in which it did not before circulate, a consequent
increase of caloric, &c. Now where the capillary system is more
developed, where the organic sensibility is greater, inflammation
ought to be more frequent; and this is the case. It is especially in
the cellular, serous, mucous and dermoid systems that we observe it;
fine injections demonstrate in these systems a capillary net-work
infinitely superior to that of the others. Besides, as if there is not
only nutrition, but also exhalation and oftentimes secretion in these
systems, there must be more organic sensibility, a property from which
all these functions are derived.
On the contrary, inflammation is rare in the muscular, osseous,
cartilaginous, fibrous, arterial, venous systems, &c. where there are
but few capillaries, and where the organic sensibility presiding only
over nutrition, is necessarily found in a less degree.
Besides, as the capillaries make an integral part of the system where
they are found, and as each system has its peculiar kind of organic
sensibility, it is evident that they ought to partake of this kind; now
as it is upon this property that all the inflammatory phenomena depend,
they ought to present an aspect wholly different in each system. This
is what we shall be convinced is the case by an examination of each. I
shall only present here generally, that essential point of view, upon
which authors have not insisted.
Let us take first the systems most exposed to inflammation; we shall
see that phlegmon is the inflammatory kind of the cellular, erysipelas
that of the dermoid, and catarrh that of the mucous. We have not yet a
general name to express that of the serous; but who does not know how
it differs from the others?
In the systems rarely subject to inflammation, we know this affection
infinitely less than in the preceding; but there is no doubt that
it differs essentially. Compare the length and permanency of that of
the bones, with the rapidity and disposition to change of that of the
muscles, or rather of the fibrous bodies, in rheumatism.
The results of inflammation do not vary less than its nature; if
resolution does not take place, each has its own mode of suppuration.
Compare the pus of erysipelas, that of phlegmon, the milky or
flocculent fluid of the serous membranes, the whitish or greyish
humour, of a mucous consistence, that escapes from the membranes of
the same name after catarrh, the blackish sanies of the bones in
suppuration, &c. We shall see that some organs, as the fibrous bodies,
do not suppurate.
Gangrene once taken place, is everywhere the same, since it is only
the absence of life, and all dead organs have the same properties. But
according to the sum of organic sensibility which each system has, it
is more or less disposed to die after inflammation, in the midst of
others which retain their life. Who does not know that the carbuncle
which soon kills the part it seizes, only attacks certain systems; that
the osseous, the cartilaginous, the nervous, &c. are always exempt from
it?
The essential fault of every medical doctrine is that of considering
diseases too abstractedly; they are so modified in each system, that
their aspect is wholly different. If I may be allowed the expression,
it is always the same individual, but in entering each system, it has a
different appearance there, so that often you cannot recognize it. When
will medicine be so far advanced that the treatment will correspond
with these varieties? There should certainly be a general treatment of
inflammation; but it should be modified differently, according as we
apply it to phlegmon, erysipelas, catarrh, &c.
This then is a very evident proof of that peculiar character which
inflammation takes in each part. We know with what ease and rapidity
the blood flows to any part of the skin in consequence of irritation
there; prick or rub briskly a part of this organ, it reddens in a
moment. This takes place also, though less sensibly, on the mucous
surfaces. This is not equally seen upon the serous; I have frequently
ascertained this on living animals, when I have laid bare these
surfaces and irritated them in different ways. The afflux of the blood
does not immediately follow the irritation: there is always an interval
between one and the other, never less than an hour.