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-The Project Gutenberg EBook of Treatise on the Anatomy and Physiology of
-the Mucous Membranes, by Xavier Bichat
-
-This eBook is for the use of anyone anywhere in the United States and most
-other parts of the world at no cost and with almost no restrictions
-whatsoever.  You may copy it, give it away or re-use it under the terms of
-the Project Gutenberg License included with this eBook or online at
-www.gutenberg.org.  If you are not located in the United States, you'll have
-to check the laws of the country where you are located before using this ebook.
-
-Title: Treatise on the Anatomy and Physiology of the Mucous Membranes
-       With Illustrative Pathological Observations
-
-Author: Xavier Bichat
-
-Translator: Joseph Houlton
-
-Release Date: September 5, 2016 [EBook #52987]
-
-Language: English
-
-Character set encoding: UTF-8
-
-*** START OF THIS PROJECT GUTENBERG EBOOK TREATISE ANATOMY OF MUCOUS MEMBRANES ***
-
-
-
-
-Produced by Sonya Schermann, John Campbell and the Online
-Distributed Proofreading Team at http://www.pgdp.net (This
-file was produced from images generously made available
-by The Internet Archive)
-
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-
-
-
-
-
-
-
-  TRANSCRIBER'S NOTE
-
-  Italic text is denoted by _underscores_.
-
-  Obvious typographical errors and punctuation errors have been
-  corrected after careful comparison with other occurrences within
-  the text and consultation of external sources.
-
-  More detail can be found at the end of the book.
-
-
-
-
-  A
-
-  TREATISE
-
-  ON
-
-  THE ANATOMY AND PHYSIOLOGY
-
-  OF THE
-
-  Mucous Membranes;
-
-  WITH
-
-  ILLUSTRATIVE PATHOLOGICAL OBSERVATIONS.
-
-
-  _From the French_
-
-  OF
-
-  XAVIER BICHAT.
-
-
-  BY JOSEPH HOULTON,
-
-  MEMBER OF THE ROYAL COLLEGE OF SURGEONS IN LONDON.
-
-
-  LONDON:
-
-  PRINTED FOR J. CALLOW,
-
-  Medical Library,
-
-  16, PRINCES STREET, CORNER OF GERRARD STREET, SOHO.
-
-  MDCCCXXI.
-
-
-
-
-CHARLES WOOD, Printer,
-
-Poppin's Court, Fleet Street, London.
-
-
-
-
-THE
-
-TRANSLATOR'S PREFACE.
-
-
-The works of no medical writer deserve a more attentive perusal
-than those of the illustrious BICHAT. Erudite, observant, and
-industrious, he, at an early age, reared a monument of science,
-which will perpetuate his name and matchless talents. From the
-rich treasures he has left, the Translator presumes to present
-this Treatise in an English costume. Where all is excellent it
-is difficult to make a satisfactory selection; yet this portion
-of the author's productions merits the particular attention of
-medical students and practitioners in general, as it leads to the
-knowledge of the structure and economy of that part of the animal
-organization, which, more than any other, is subject to morbid
-affections.
-
-The aim of the Translator has been faithfulness, clearness, and
-conciseness, rather than elegance: how he has fulfilled his
-intention he must leave to the decision of the candid Reader.
-
-  SAFFRON WALDEN,
-  JULY 1, 1821.
-
-
-
-
-CONTENTS.
-
-
-  SECT.                                                             PAGE
-
-     I. _Of the Situation and Number of Mucous Membranes_              1
-
-    II. _Of the Exterior Organization of Mucous Membranes_             9
-
-   III. _Of the Interior Organization of Mucous Membranes_            20
-
-    IV. _Of the Glands of Mucous Membranes_                           37
-
-     V. _Of the Vascular System of Mucous Membranes_                  54
-
-    VI. _Of the Variations in the Organization of Mucous Membranes_   64
-
-   VII. _Of the Vital Powers of Mucous Membranes_                     70
-
-  VIII. _Of the Sympathies of Mucous Membranes_                       81
-
-    IX. _Of the Functions of Mucous Membranes_                        85
-
-     X. _Remarks on the Affections of Mucous Membranes_               98
-
-
-
-
-A
-
-TREATISE
-
-ON
-
-MUCOUS MEMBRANES.
-
-
-
-
-SECTION I.
-
-OF THE SITUATION AND NUMBER OF MUCOUS MEMBRANES.
-
-
-1. The Mucous Membranes occupy the interior of those cavities,
-which, by various openings, communicate with the skin. Their
-number, at the first view, appears very considerable; for the
-organs within which they are reflected are numerous. The stomach,
-bladder, urethra, uterus, ureters, the intestines, &c., borrow from
-these membranes a part of their structure: nevertheless, if it be
-considered, that they are continuous throughout, that everywhere
-they are observed to be extended from one organ to others, arising,
-as they did at first, from the skin, their number will appear to
-be singularly limited. In fact, in thus contemplating them, not as
-insulated in each part, but as continued over various organs, it
-will appear that they are reducible to two general surfaces.
-
-2. The first of these two surfaces, entering by the mouth, nose,
-and anterior surface of the eye, (1) lines the first and second
-of these cavities: from the first it extends into the excretory
-ducts of the parotid and submaxillary glands; from the other it is
-continued into all the sinuses, it forms the tunica conjunctiva,
-descends by the puncta lacrymalia through the canal and lacrymal
-sac to the nose. (2) It descends into the pharynx, and there
-furnishes the inner surface of the Eustachian tube, and thence
-it penetrates and lines the internal ear. (3) It sinks into the
-trachea, and spreads itself over all the air passages. (4) It
-enters the œsophagus and stomach. (5) It extends into the duodenum,
-where it furnishes two branches, one destined to the ductus
-communis choledochus, to the numerous rami of the hepatic duct, to
-the cystic duct and gall bladder; the other to the pancreatic duct
-and its various ramifications. (6) It is continued into the small
-and large intestines, and finally terminates at the anus, where it
-is identified with the skin.
-
-3. The second general mucous membrane enters, in men, by the
-urethra, and thence spreads from one part through the bladder,
-ureters, pelves, calices, papillæ, and uriniferous tubes; from the
-other it sinks into the excretory ducts of the prostate gland,
-into the ejaculatory ducts, the vesicula seminales, the vassa
-defferentia, and the infinitely convoluted branches from which they
-arise. In women, this membrane enters by the vulva, and from one
-part penetrates the urethra, and is distributed, as in men, through
-the urinary organs; from the other part it extends into the vagina,
-which it lines, as it also does the uterus and the fallopian tubes,
-and through the apertures at the extremities of these ducts it
-comes in contact with the peritoneum. This is the only example
-in the economy, of a communication between the mucous and serous
-surfaces.
-
-4. This manner of describing the track of the mucous surfaces by
-saying that they extend, sink, penetrate, &c., from one cavity
-to another, is certainly not conformable to the march of nature,
-which forms in each organ the membranes that belong to it, and
-does not thus extend them from one to the other; but our manner
-of conceiving is best accommodated by this language, of which the
-least reflection will rectify the sense.
-
-5. In thus bringing all the mucous surfaces to two general
-membranes, I am supported, not only by anatomical inspection,
-but pathological observation also furnishes me with lines of
-demarcation between the two, and with points of contact between
-the different portions of the membranes of which each is the
-assemblage. In the various sketches of epidemic catarrhs made
-by authors, we frequently see one of these membranes has been
-affected throughout its extent, whilst the other, on the contrary,
-has remained untouched. It is not uncommon to observe a general
-affection of the first, _viz._ that which extends from the mouth,
-nose, and anterior surface of the eye, into the alimentary canal
-and bronchi. The last epidemic observed at Paris, with which M.
-Pinel was himself affected, bore this character: that of 1761,
-described by Rayons, presented the same feature: that of 1732,
-described in the Memoirs of the Edinburgh Society, was remarkable
-for a like phenomenon. Now we do not see at the same time a
-corresponding affection in the mucous membrane which spreads over
-the organs of urine and of generation. Here is, therefore, (1)
-an analogy between the different portions of the first, by the
-uniformity of the affection; (2) a line of demarcation between
-them, by the healthy state of the one and the disease of the other.
-
-6. We observe also, that irritation on any one point of these
-membranes frequently produces a pain in another point of the same
-membrane, which is not irritated; thus a stone in the bladder
-causes a pain at the end of the glans, worms in the intestines
-produce an itching at the nose, &c. &c. Now in these phenomena,
-which are purely sympathetic, it is extremely rare that the partial
-irritation of one of these two membranes produces a painful
-affection in a part of the other.
-
-7. We ought, therefore, from inspection and observation, to
-consider the mucous surface in general as formed by two grand
-membranes, spread over several organs, and having no communication
-with each other but by the skin, which is intermediate, and which,
-being continuous with both, thus concurs with them to form a
-general membrane, entire throughout, enveloping the exterior of the
-animal, and extending to the interior over most of its essential
-parts. It should seem, that there exists important relations
-between the internal and external portions of this unique membrane,
-and this we shall soon be shown by ulterior researches.
-
-
-
-
-SECTION II.
-
-OF THE EXTERIOR ORGANIZATION OF MUCOUS MEMBRANES.
-
-
-8. Every mucous membrane presents two surfaces; the one adhering
-to the adjacent organs; the other free, beset with villosities,
-and always moist with a mucous fluid: each of them deserves a
-particular attention.
-
-9. The adherent surface is attached to muscles almost throughout
-its extent. The mouth, the pharynx, the whole of the alimentary
-canal, the bladder, the vagina, the uterus, and part of the
-urethra, &c. present a muscular bed, embracing the exterior of
-their mucous coat. In animals that have the panniculus carnosus,
-this disposition perfectly coincides with that of the skin, which,
-as we shall see, is in other respects analogous in structure
-to mucous membranes. In man the cutaneous organ presents here
-and there traces of this exterior muscle, as we observe in the
-platysma myoides, the palmaris brevis, the occipito frontalis, in
-most of the muscles of the face, &c. This disposition of mucous
-membranes places them under the influence of those habitual changes
-of contraction and dilatation, which are favourable to their
-secretion, and various other functions.
-
-10. This muscular bed is not immediately inserted into the exterior
-surface of the mucous membranes, but rather, according to Albinus,
-into a dense layer of cellular tissue, which all the ancient
-authors have denominated, in the stomach, intestines, and bladder,
-the nervous coat; but when well examined it presents no character
-analogous to that which the name indicates. The experiment of
-inflation, by which it is brought into its primitive state, is not
-so easy as Albinus and others have pretended; which led me to think
-that its nature might not be cellular, but that it was probably
-of a fibrous texture, formed by a web of extremely delicate and
-scarcely visible tendons, offering points of origin and insertion
-to all the fleshy fibres of the muscular bed, which, as we know,
-never describe entire circles, but rather different segments of
-that curve. I confess that this conjecture, though very likely, is
-not founded upon any decisive and rigorous experiment.
-
-11. Whatever may be the nature of this intermediate membrane to
-the mucous and muscular coats, it evidently has a dense, close
-texture, which gives it a resistance very analogous to one of the
-fibrous membranes. It is from this that the organ receives its
-form; it is this which maintains and controls its shape, as may be
-proved by the following experiment. Take a portion of intestine:
-remove in any part of the bowel a part of this membrane, with the
-serous and muscular membranes: having applied a ligature to the
-inferior end, inflate it, the air will produce in the denuded part
-an hernia of the mucous coat. Take another portion of intestine,
-turn it, dissect off a small part of the mucous membrane and of
-this coat: inflation will produce upon the serous and muscular
-coats the same phenomenon as in the preceding case it did in the
-mucous membrane. It is therefore to this intermediate tunic that
-the mucous membrane owes its power of resistance to substances
-which distend it. This applies equally to the stomach, bladder,
-œsophagus, &c.
-
-12. The free surface of mucous membranes, or that which is
-continually moistened by the fluid from which they borrow their
-name, presents two kinds of wrinkles or folds, the one inherent
-in their structure and which is constantly present, whatever may
-be their state of contraction or dilatation, such as the pylorus,
-the valvula conniventes, the valve of the colon, &c. These folds
-are formed, not merely by the mucous membranes, but also by the
-intermediate membrane mentioned above, and which in these parts
-takes a remarkable density and thickness.
-
-13. The other folds may be called accidental, and are only observed
-during the contraction of the organ; such are those of the inner
-surface of the stomach, and of the large intestines, &c. In most
-of the human subjects brought to our amphitheatres, these folds in
-the stomach, of which so much has been said, are not perceptible,
-because generally the subject has died of a disease which has
-impaired the vital powers, without preventing all the action of
-this viscus; so that, although it is frequently found empty, its
-fibres are not in the least contracted.
-
-14. In experiments on living animals, on the contrary, these folds
-are very apparent; and observe how they may be demonstrated.
-Let a dog eat or drink copiously; open it immediately, and make
-an incision into the stomach the whole length of its greater
-curvature, no fold will then appear, but it soon contracts, its
-edges are drawn in, and the whole of the mucous surface is covered
-with numerous prominent plicæ in the form of circumvolutions. The
-same result may be observed in the stomach of a recently killed
-animal by distending it with air, and then opening it; or, what is
-still better, by laying it open whilst empty, and stretching it,
-the folds will disappear, and when we cease to make the extension
-they immediately form again and are very apparent.
-
-15. I would observe on the subject of inflating the stomach, that
-by distending it with oxygen gas the application of this fluid
-does not produce more prominent folds, and therefore no stronger
-contraction, than when carbonic acid gas is used for the same
-purpose. This experiment presents a result very similar to what
-I have observed when I have rendered animals emphysematous by
-different æriform fluids. Frogs and Guinea pigs (these are the two
-kinds I have chosen, the one being an animal of red and cold, and
-the other of red and warm blood) presented very little difference
-in their irritability, or their Galvanic susceptibility, whether
-inflated with oxygen gas or with carbonic acid gas. They live very
-well with this artificial emphysema, which gradually disappears.
-Inflation with nitrous gas is always mortal, and its contact
-appears to strike the muscles with atony. The stomach distended
-with it very soon loses its power of contracting, and its folds
-disappear. Here, as in all the experiments which have the vital
-powers for their object, we frequently obtain very variable results.
-
-16. It follows, from what we have said respecting the folds of
-mucous membranes, that in the contraction of the hollow organs,
-which are lined by them, they suffer but a very trifling diminution
-of surface, they scarcely contract at all, but fold themselves
-within; so that in dissecting them upon their contracted organ, we
-have an extent of surface nearly equal to that which they present
-during its dilatation. This assertion, which is true concerning
-the stomach, the œsophagus, and the intestines, is, perhaps, not
-quite so as respects the bladder, whose contraction does not show
-within such prominent folds, but they are sufficiently marked to
-bring the mucous membrane of this organ under the general law.
-It is, also, nearly the same with the gall bladder; yet we find
-here another cause; observed alternately, in a state of hunger and
-during digestion, it will be found to contain double the quantity
-of bile in the former case that it does in the latter, as I have
-had the opportunity of seeing in numerous instances, in experiments
-made with this object in view, or with other intentions. Now, when
-it has evacuated part of its contents it does not contract upon
-the remainder of the bile, with the energy of the stomach when it
-contains but little food, nor with the power of the bladder when
-it contains but a small quantity of urine, but is then flaccid,
-so that its distention or nondistention has but very trifling
-influence upon the folds of its mucous membranes.
-
-17. Moreover, in saying that the mucous membranes present with
-trifling variation the same extent of surface in the dilatations
-as during the contraction of their respective organs, I intend to
-speak of the ordinary state of the functions only, and not of those
-enormous dilatations which are frequently seen in the stomach and
-bladder, more rarely in the intestines. In such cases there is
-doubtless a real extension, which in the membrane coincides with
-that of the organ.
-
-18. One remarkable observation that the free surface of mucous
-membranes affords us, and which I have already pointed out,
-is, that this face is everywhere in contact with bodies of a
-different nature to that of the animal: these bodies are either
-introduced from without for its nourishment, and are not yet
-assimilated to its substance, as we see in the alimentary canal
-and in the trachea, or they are produced within, as we observe in
-the excretory ducts of the glands, which all open into cavities
-lined by mucous membranes, and discharge those particles, which,
-after having for some time formed a part of the composition of
-the solids, become heterogeneous to them, and are thrown off
-by that habitual action of decomposition, which takes place in
-living bodies. According to this observation we must consider the
-mucous membranes as defensive coats, placed between our organs and
-foreign bodies, and that they consequently serve the same purpose
-internally which the skin does externally, as respects bodies that
-are in contact with it.
-
-
-
-
-SECTION III.
-
-OF THE INTERIOR ORGANIZATION OF MUCOUS MEMBRANES.
-
-
-19. Between the mucous and other membranes, as respects their
-interior organization, there is this essential difference, that
-they are always formed by several thin fibrous layers; these layers
-or coats are, with the exception of the rete mucosum, the same as
-those which compose the skin with which these membranes have the
-most exact analogy. We are about to examine separately each of
-these layers, which are the epidermis, the corps papillaire, and
-the chorion, in their general attributes; we shall afterwards
-consider the particular modifications which they undergo in the
-different parts of the mucous surfaces.
-
-20. All authors have admitted the epidermis of mucous membranes:
-it appears, even, that the greatest part of them have believed
-that it is merely that portion of the skin which descends into the
-cavities to line them; Haller in particular is of this opinion; but
-the least inspection is sufficient to show, that here, as in the
-skin, it forms but a layer superficial to the corps papillaire and
-chorion; boiling water, which detaches it from the surface of the
-palate, the tongue, and even from the pharynx, leaves the two other
-coats denuded and apparent.
-
-21. This epidermis is very distinct upon the glans, at the anus, at
-the orifice of the urethra, at the entrances of the nasal fossæ,
-and of the mouth, and in general wherever the mucous membranes
-arise from the skin. It is demonstrated in these different places
-by the frequent excoriations which occur on them; it may be raised
-from the lips by a very fine lancet by the action of boiling water,
-a hot iron, or even by epispastics, as the method of the ancients
-proves, who employed them to produce a fresh raw surface for the
-cure of the hare lip.
-
-22. But in proportion as we go into the depth of the mucous
-membranes, the existence of this coat becomes more difficult to be
-demonstrated; it cannot be raised by the finest instrument, nor
-detached by boiling water, at least in the gall bladder, in the
-stomach, and intestines. I have made these experiments in fresh
-slain animals, and also in those where the natural heat had quite
-left them. But what our experiments cannot effect, inflammations
-will often produce. All the authors, who have written on the
-affections of the organs which are lined by these membranes,
-mention instances in which flakes, more or less considerable, have
-been voided by the urethra, anus, mouth, nostrils, &c. Haller has
-collected a great number of similar observations. Without doubt
-the separation of the epidermis in these cases is produced nearly
-in the same way as we observe it in cutaneous inflammations. In
-many subjects that have died with symptoms of inflammation of the
-mucous membranes, and which I have already had the opportunity of
-dissecting, or of seeing dissected, I have not yet been able to
-observe this separation going on; that is to say, the epidermis
-separated at one point, and still remaining adherent at others, as
-in erysipelas. I have tried in vain to produce this effect by the
-application of an epispastic to the inner surface of the intestines
-of a dog.
-
-23. This epidermis is subject, like that of the skin, to become
-callous by pressure. Choppart cites a case of a shepherd, "dont
-le canal de l'urètre présentoit cette disposition, à la suite de
-l'introduction fréquemment répétée d'une petite baguette pour se
-procurer des jouissances voluptueuses." We know the density that
-this envelope takes in the stomachs of the gallinacea. In certain
-circumstances, where the mucous membranes are protruded from
-the body, as in prolapsus ani, inversion of the vagina, in the
-artificial anus, &c., sometimes the pressure of the dress produces
-in this epidermis a thickness evidently more considerable than is
-natural to it.
-
-24. The epidermis is attached to the hair on the skin, although
-it does not afford its immediate origin; sometimes also piliform
-productions are observed in the mucous membranes. The bladder, the
-stomach, the intestines, and the pituitary membrane have been in
-various instances the seat of these unnatural excrescences: Haller
-has cited various instances of them.
-
-25. This envelope appears to have upon the mucous surfaces the
-same texture as on the skin, excepting in the delicacy of the
-laminæ from which it is produced. It is to this delicacy, which
-gives more exposure to the nerves, that we must doubtless refer
-the facility with which we excite various remarkable modifications
-in the sensibility, when by the Galvanic process we apply zinc to
-the mucous surface of the conjunctiva, the pituitary membrane, the
-internal membrane of the rectum, or of the gums, &c., and bring
-these several metal plates into mediate or immediate contact. The
-epidermis when removed is quickly reproduced; being destitute
-of all kinds of sensibility, it in this respect serves the same
-purpose as the skin, by guarding the very sensible corps papillaire
-which is subjacent to it. To its presence over the mucous membranes
-we must attribute the ability they have of being exposed to the
-air, and even to the contact of foreign bodies, without excoriating
-or inflaming, as is seen in cases of artificial anus, prolapsus
-ani, &c., whilst serous and fibrous membranes never suffer such
-exposure with impunity. Hence there is no danger, in this respect,
-from opening the bladder: hence, on the contrary, that precept so
-justly recommended, not to open the cavity of the peritoneum, and
-to make the least possible incision into the synovial capsules.
-I would observe, that the existence of the epidermis upon mucous
-membranes is an important consideration, as respects the opinion
-of those who, like Séguin, believing them to be without it, have
-said, that contagion is always received by the lungs, and not by
-the skin, which is, according to them, defended by this envelope.
-
-26. In the organization of the skin, immediately under the
-epidermis is placed the corpus mucosum, particularly described by
-Malpighi, and generally considered as the seat of colour in the
-different varieties of the human species. It is described as a
-coat, pierced with holes by the passage of the nervous papillæ: M.
-Sabattier points out the manner of demonstrating it. Sömmering has,
-it is said, seen it separated from the epidermis and chorion on the
-scrotum of an Ethiopian. I confess that I have not yet been able to
-perceive it: M. Portal does not appear to have been more fortunate.
-
-27. We distinguish only a kind of gelatinous juice intermediate
-to the corps papillaire and epidermis, and most commonly it is
-not even apparent; I have never been able to observe more with
-certainty. In examining the skin of a Negro with attention, the
-epidermis being detached, I have seen the external surface of the
-chorion tinged with black, and that was all. Further, whatever
-this corpus mucosum may be, it certainly does not exist in mucous
-membranes, since they do not participate in the colour of the
-integuments. The heat of the sun, which darkens these in white
-people, does not appear to act upon the commencement of these
-membranes, which are equally exposed with them to its influence,
-as is seen in the red borders of the lips, &c. Nevertheless, I
-have many times remarked on the palates of dogs, which have been
-the subjects of my experiments, similar spots to those which have
-marked their skin.
-
-28. The sensibility of the skin is principally owing to the corps
-papillaire; that of the mucous membranes, exactly analogous to
-that of the skin, appears to me to arise from the same cause. The
-nervous papillæ of these membranes cannot be questioned: at their
-origin, where they dip into the cavities, even in the commencement
-of these cavities, as on the tongue, the palate, the internal
-surface of the alæ nasi, on the glans, in the fossa naviculare,
-on the inside of the lips, &c., inspection is sufficient to
-demonstrate them. But, we ask, do these papillæ exist also in those
-parts of mucous membranes which are more remote from the surface of
-the body? Analogy answers in the affirmative, since sensibility is
-the same there as at their origin; but inspection proves it in a
-no less certain manner. I believe, that the villosities with which
-we see them everywhere thickly furnished are nothing else than
-these papillæ.
-
-29. Very different notions have been entertained concerning the
-nature of these villosities: they have been considered, in the
-œsophagus and in the stomach, as destined to the exhalation of the
-gastric juice, in the intestines as serving for the absorption of
-chyle, &c. But (1) It is difficult to conceive how an organ, so
-nearly similar throughout its extent, should fulfil, in different
-parts, such different functions; I say so nearly similar, because
-we know, that the villosities of the small are more prominent than
-those of the large intestines. (2) What would be the functions of
-the villosities of the pituitary membrane, of the internal coat
-of the urethra, and of the bladder, if they had no connection
-with the sensibility of these membranes. (3) The microscopic
-experiments so boasted of by Leiberkuhn, on the erection of the
-intestinal villosities, have been contradicted by those of Hunter
-and Cruikshank, and, above all, by those of Hewson. I can assert,
-that I have never seen any thing of the kind on the surface of
-the small intestines during the absorption of chyle, and yet it
-appears to be a thing that cannot vary in different examinations.
-(4) It is true that these intestinal villosities are everywhere
-accompanied by a vascular web, which gives them a colour very
-different from that of the cutaneous papillæ; but the nonappearance
-of the cutaneous web is occasioned only by atmospherical pressure,
-by means of the contraction that it produces in the minute vessels:
-see, for instance, the newly-born infant; its cutaneous surface is
-as red as that of its mucous membranes, and if the papillæ were a
-little more elongated the skin would exactly resemble the internal
-surface of the intestines: moreover, who does not know, that the
-vascular web surrounding the papillæ is rendered so apparent by
-fine injections as entirely to change the colour of the skin?
-
-30. That in the stomach this vascular web exhales the gastric
-juice, and in the intestines it is interlaced with the origin of
-the absorbents, so that they embrace the villosities, are facts
-that we must admit, after the experiments and observations of the
-anatomists, who in these times have been engaged with the lymphatic
-system: but that does not contradict the assertion, that the bases
-of these villosities are nervous, and perform the same functions
-only on the mucous membrane as the papillæ do on the cutaneous
-organ. This view of them, by explaining their existence as observed
-generally over all the mucous surfaces, appears to me much more
-conformable to the plan of nature than to suppose that they
-perform, in their different parts, diverse and frequently opposite
-functions.
-
-31. However, it is difficult to decide the question by ocular
-observation; the tenuity of these prolongations conceals their
-structure even from our microscopic instruments, a kind of agents
-by which physiology and anatomy do not appear to me in other
-respects ever to have obtained great assistance, because when parts
-are so viewed each person sees in his own way, and is impressed
-accordingly. It is therefore the observing of the vital functions
-that should above all guide us. Now by judging of the villosities
-in this way it appears evident, that they have the nature which
-I have attributed to them. The following experiment will serve
-to demonstrate the influence of the corps papillaire upon the
-cutaneous sensibility: it succeeds also with mucous membranes.
-If we remove any part of the epidermis, and irritate the corps
-papillaire with a pointed instrument, the animal writhes, cries,
-and gives signs of acute pain. If afterwards the cutis be pierced,
-and with the instrument the internal surface of the chorion be
-irritated, the animal will not appear to suffer pain, unless by
-accident some nervous filaments should be touched. Thence it
-follows very evidently, that the sensibility of the skin resides
-in its external surface, that the nerves pass through the chorion
-without being interwoven with its texture, and that their diffusion
-only takes place on the corps papillaire. It is the same in mucous
-surfaces.
-
-32. The length and form of the villosities vary in the different
-mucous surfaces. Their appearance is not the same in the stomach,
-the intestines, the bladder, the gall bladder, on the glans, &c.;
-which variation exactly coincides with the sensibility peculiar to
-each organ, a sensibility proved by numerous observations since
-Bordeu, who was the first to direct the attention of physiologists
-to the particular modifications that this property undergoes in the
-different parts.
-
-33. Like the skin, the mucous membranes have their chorion: it is
-thick on the palate, gums, and pituitary membrane, delicate in the
-stomach and intestines, not very distinct in the bladder, gall
-bladder, and excretory ducts. It appears to be formed of condensed
-cellular strata, strongly united, as in the skin. Maceration
-develops this texture in a very sensible manner. There is
-nevertheless this difference, that in dropsy the cutaneous chorion
-rises and resolves itself into distinct cellules, that become
-filled with water, whilst no such change takes place in the mucous
-chorion under similar circumstances. Does this difference in the
-morbid state suppose a dissimilarity of structure? Certainly not;
-for the synovial membrane is evidently of the same nature as the
-serous membranes; and nevertheless it does not participate in the
-hydropic diathesis which often affects them universally. It would
-be curious to expose mucous membranes to the action of tan, to see
-if they would present the same phenomena as the skin.
-
-
-
-
-SECTION IV.
-
-OF THE GLANDS OF MUCOUS MEMBRANES.
-
-
-34. Besides the three strata, which we have just mentioned, the
-mucous membranes present in their structure a great number of
-glands and blood vessels. The mucous glands exist in all membranes
-which bear that appellation: they are situate under their chorion,
-and even in its substance: they continually discharge, through
-imperceptible orifices, a mucilaginous fluid, which lubricates
-their free surface, and defends it from the impression of the
-bodies with which it is in contact, at the same time that it
-facilitates the passage of those substances.
-
-35. These glands, which are very apparent in the bronchi, palate,
-œsophagus, and intestines, where they take the name of the
-anatomists who have particularly described them, are less obvious
-in the bladder, the gall bladder, uterus, vesiculæ seminales,
-&c.; but the mucus which moistens the membranes unequivocally
-demonstrates their existence. In fact, since this fluid is nearly
-of the same nature on all the mucous surfaces, and, in those where
-the glands are apparent, is evidently furnished by them, it must be
-secreted in the same manner in those where they are less evident.
-The identity of secreted fluids, certainly, supposes the identity
-of the secreting organs. It should seem, that in situations
-where these glands escape our observation, nature makes up for
-their tenuity by increasing their number. In the lower animals,
-particularly in the intestines, they form by their number a kind
-of new layer, in addition to those we have described. The same may
-be observed in the palate, velum, &c. in man.
-
-36. There is therefore this great difference between mucous and
-serous membranes; that the fluid which lubricates the former is
-furnished by secretion, whilst that which moistens the latter is
-produced by exhalation. We know but little of the composition
-of mucous fluids, because in the natural state it is difficult
-to collect them, and in the morbid state, where their quantity
-increases, as for instance in catarrhs, their composition probably
-undergoes some alteration: but their functions in the animal
-economy are well ascertained.
-
-37. The first of these functions is to defend the mucous membranes
-from the impressions of the bodies with which they are in contact,
-and which, as we have observed, are all heterogeneous to the
-animal. Here, without doubt, we see the reason why the mucous
-fluids are more abundant in the cavities where these bodies remain
-for some time, as in the bladder, at the extremity of the rectum,
-&c., than in those organs through which they merely pass, as in
-the ureters, and in general in all the excretory ducts. Observe
-again, why, when the impression of these bodies might be hurtful,
-these fluids are poured out upon their surfaces in a much greater
-quantity. The sound which is introduced into the urethra, and is
-allowed to remain there; the instrument that is left in the vagina
-to secure a polypus; that which, with a similar intention, remains
-some time in the nasal fossæ; the canula, fixed in the lacrymal
-sac, to remove the obstruction; and the tube that is introduced
-into the œsophagus, when deglutition is interrupted, always
-determine a more plentiful secretion upon the corresponding mucous
-surface. This is one of the principal causes why it is so difficult
-to retain elastic tubes in the trachea; the abundance of mucous
-fluid, which is then separated, chokes up the apertures of the
-instrument, and renders its frequent removal necessary, and may
-even threaten the patient with suffocation, as Desault has himself
-observed, although he has nevertheless many times succeeded with
-that operation.
-
-38. It therefore appears, that every acute excitement of mucous
-surfaces determines, in the corresponding glands, a remarkable
-augmentation of action. But how can this excitement, which does
-not take place immediately upon the glands, have so great an
-influence over them? For, as we have said, these glands are always
-subjacent to the membrane, and are consequently separated by it
-from the irritating bodies. It appears that the above fact belongs
-to a general modification of the glandular sensibility, which is
-susceptible of being put into action by every irritation upon the
-extremities of the excretory ducts, which will be proved by the
-following considerations: (1) The presence of food in the mouth
-produces a more abundant flow of saliva. (2) The catheter fixed
-in the bladder, and irritating the ureters, or their vicinity,
-increases the flow of urine. (3) The introduction of a bougie, but
-half way up the urethra, will often be sufficient to occasion the
-bladder to contract with a power equal to force the urine through
-the passage, and so to overcome an obstruction in the canal. (4)
-The irritation of the glans, and of the extremity of the urethra,
-sub coitu, determines the contraction of the vesiculæ seminales,
-and augments the secretory action of the testes. (5) The action
-of an irritating fluid on the tunica conjunctiva occasions an
-abundant flow of tears. (6) In making experiments upon the state
-of the abdominal viscera during digestion, and under the influence
-of hunger, I have observed, that whilst the food is only in the
-stomach there is very little flow of bile; but it increases
-when the aliment passes into the duodenum, so that then there
-is a considerable quantity in the intestines. During hunger the
-gall bladder is distended, and but little bile flows into the
-intestines. At the end of digestion, and even when that process
-is half finished, the gall bladder contains but half of its full
-quantity; yet it might be expected to empty itself more easily
-during abstinence, for then the bile it contains is of a deep
-green colour, very bitter, very acrid, and likely to irritate the
-organ which encloses it. On the contrary, during, or immediately
-after digestion, it is more clear, mild, and less irritating;
-there must, therefore, be, during digestion, another stimulus: now
-this stimulus is the aliment passing over the mouth of the ductus
-communis choledochus[A].
-
-39. Let us conclude, from these numerous considerations, that one
-of the principal means that nature employs to augment the action
-of the glands, and to excite that of their excretory ducts, is
-irritation upon the extremities of these ducts. We must refer to
-that cause the abundant secretion and excretion of mucous fluids
-in the cases above stated. It is also to this susceptibility of
-the mucous glands, to be excited by irritation at the extremities
-of their excretory ducts, that we must attribute the artificial
-catarrhs which are occasioned by the respiration of chlorine
-gas; the flow of mucus which attends a polypus, any tumour in
-the vagina, stone in the bladder, &c. The frequent occurrence of
-leuchorrhea in women who use coition immoderately, the abundant
-flow of mucus from the noses of those persons who take snuff, in
-all these cases there is evidently an irritation of the mouths of
-the mucous ducts.
-
-40. The mucous membranes, by the continual secretion of which they
-are the seat, perform a principal part in the animal economy.
-They are to be regarded as one of the grand emunctories, by which
-the residue of the nutriment constantly escapes from the body;
-and consequently as one of the principal agents of that habitual
-decomposition which carries away from living bodies the particles
-which for some time formed part of the solids, but have at length
-become heterogeneous to them.
-
-41. Remark the fact, that none of the mucous fluids enter into
-the circulation, but are thrown out externally; that of the
-bladder, ureters, and urethra, with the urine; that of the vesiculæ
-seminales and of the vassa defferentia with the semen; that of
-the nostrils by the action of blowing the nose; that of the mouth
-partly by evaporation, and partly by the anus with the excrements;
-that of the bronchi by the pulmonary exhalation, which is effected
-principally by the solution of this mucous fluid in the air of
-respiration; those of the œsophagus, of the stomach, of the
-intestines, of the gall bladder, &c., with the excrements of which
-they frequently form, in the ordinary state, a part nearly equal to
-the residue of the aliment; and they even compose almost the whole
-of the matter voided in certain dysenteries and fevers, where the
-quantity is evidently disproportionate to the food that has been
-taken. Let us observe on this subject, that in the analysis of the
-fluids, in contact with the membranes of which we speak, as the
-urine, bile, gastric juice, &c., there are always some errors,
-because it is very difficult, impossible even, to separate them
-from the mucous fluids.
-
-42. If we call to mind what has been said above, upon the extent
-of the two general mucous surfaces, that they are equal and even
-superior to the extent of the cutaneous organ; if we afterwards
-contemplate these two grand surfaces, constantly throwing off the
-mucous fluids, we shall see of what importance this evacuation
-must be in the economy, and of what derangements its lesion may
-become the source. It is doubtless to this law of nature, which
-ordains that every mucous fluid shall be rejected externally, that
-in the fœtus we must attribute the presence of the unctuous fluid,
-of which the gall bladder is full, and of the meconium choking up
-the intestines, &c., kinds of fluids which appear to be only a
-collection of mucous juices, which, as they cannot be evacuated,
-remain, until birth, upon the organs where they have been secreted.
-
-43. It is not the mucous fluids only that are rejected externally;
-almost all the fluids, separated from the mass of blood by the
-means of secretion, have the same destiny: this is evident in
-the most considerable part of the bile. It is very probable,
-also, that the saliva, the pancreatic juice, and the tears, are
-discharged with the fæces, and that it is their want of colour
-alone that prevents them from being distinguished like the bile.
-I do not know even if, in reflecting on a crowd of phenomena, one
-would not be tempted to establish, as a general principle, that no
-fluid, separated by secretion, returns into the circulation; that
-this destination belongs only to fluids separated by exhalation,
-as those of the serous cavities, of the articulations, of the
-medullary organ, &c.; that all the fluids are thus excremental or
-recremental, and that there is no recremental excrement, as the
-common division points out[B].
-
-44. What is certain, at least, is, (1) that I have never been able
-to effect the absorption of bile or saliva by the lymphatics.
-When I have injected them into the cellular tissue of an animal
-they have always produced inflammation and suppuration. (2) We
-know that the urine, when infiltrated, does not become absorbed,
-and that it strikes with death every part that it touches; whilst
-the infiltrations of lymph, or of blood, are readily absorbed.
-(3) There is an essential difference between the blood and the
-secreted fluids as concerns their decomposition, whilst exhaled
-fluids and serum, &c., are in that respect very similar.
-
-
-
-
-SECTION V.
-
-OF THE VASCULAR SYSTEM OF MUCOUS MEMBRANES.
-
-
-45. The mucous membranes receive a great number of vessels: the
-remarkable redness which distinguishes them would be sufficient
-to prove it to us, if it could not be demonstrated by injections.
-This redness is not everywhere uniform; it is less in the bladder,
-large intestines, and frontal sinuses; very marked in the stomach,
-small intestines, and vagina, &c. It is produced by a web of
-very numerous vessels, whose supplying branches, after having
-passed through the chorion, finish on its surface by an infinite
-division, embracing the corps papillaire, and is covered only by
-the epidermis.
-
-46. It is the superficial position of these vessels that frequently
-exposes them to hæmorrhages, as we remark principally in the nose,
-and as is seen in hæmoptysis, hæmatemæsis, hæmaturia, in certain
-dysenteries, where the blood escapes from the parieties of the
-intestines, in uterine hæmorrhages, &c.; so that those spontaneous
-hæmorrhages, which are independent of any external violence applied
-to the open vessels, appear to be special affections of the mucous
-membranes; they are seldom observed but in these organs, and they
-form at least one of the grand characteristics which distinguishes
-them from all the other membranes.
-
-47. It is also the superficial situation of the vascular system of
-mucous membranes that renders their visible portions, as on the
-lips, the glans, &c.; serviceable in showing us the state of the
-circulation. Thus, in various kinds of asphyxia, in submersion,
-strangulation, &c., these parts present a remarkable lividity; the
-effect of the difficulty that the venous blood finds in passing
-through the lungs, and of its reflux towards the surfaces where the
-venous system arises from that of the arteries.
-
-48. I have already observed in the fœtus, and newly born infant,
-that the vascular system is as apparent in the cutaneous organ
-as in the mucous membranes; that the redness is there the same;
-it is even in that part more marked in the earlier periods of
-conception; but soon after birth all the redness of the skin seems
-to concentrate itself upon the mucous membranes, which before,
-being inactive, had no need of so considerable a circulation, but
-which, becoming all at once the principal seat of the phenomena
-of digestion, of the excretion of the bile, of the urine, of the
-saliva, &c., demand a larger quantity of blood. The long continued
-exposure of mucous membranes to the air frequently occasions them
-to lose their characteristic redness, and they then assume the
-colour of the skin (as M. Sabattier has well observed in treating
-on prolapses of the uterus and vagina). By this circumstance some
-have been deceived in believing such instances to be cases of
-Hermaphrodism.
-
-49. An important question in the history of the vascular system of
-the mucous membranes presents itself, which is, does this system
-admit more or less blood, according to its various circumstances?
-As the organs within which this sort of membrane is spread are
-nearly all of them susceptible of contraction and dilatation, as
-is observable in the stomach, intestines, bladder, &c., it has
-been believed, that during their dilatation the vessels, being
-more spread out, received more blood, and that during their
-contraction, on the contrary, being folded on themselves, and as
-it were strangulated, they admitted but a small portion of this
-fluid, which then flows back into the adjacent organs. M. Chaussier
-has applied these principles to the stomach, the circulation of
-which he has considered as being alternately the inverse of that
-of the omentum, which receives, during the vacuity of that organ,
-the blood which it, being in a state of contraction, cannot admit.
-Since M. Lieutaud, an analogous use has been attributed to the
-spleen. Observe what I have ascertained on this subject from the
-inspection of animals opened during abstinence, and in the various
-periods of digestion.
-
-50. (1) Whilst the stomach is in a state of repletion its vessels
-are more apparent on its exterior surface than during its vacuity;
-its mucous surface at this time has no higher degree of redness,
-but it has sometimes appeared to me to be less red than when the
-viscus was empty. (2) The omentum, being less extended during
-the plenitude of the stomach, presents nearly the same number of
-apparent vessels, equal in length, but more folded upon themselves
-than during the vacuity of that organ[C]. If they are then less
-loaded with blood the difference is scarcely perceptible. I would
-here observe, that great care is requisite in opening the animal,
-or the blood will fall upon the omentum, and prevent us from
-ascertaining its real state. (3) I am confident that there is no
-such constant relation between the volume of the spleen and the
-stomach in its different states of vacuity or plenitude; and if
-that organ increases and diminishes under various circumstances,
-it is not always in the inverse ratio of the state of the stomach.
-Like Lieutaud, I at first made experiments on dogs, in order to
-satisfy myself respecting the facts just stated; but the inequality
-in the size and age of those which were brought to me leading
-me to fear that I might not be able to compare their spleens
-correctly, I repeated them on Guinea pigs, whose size and condition
-corresponded, and examined, at the same time, some whilst the
-stomach was empty, and others whilst it was full. I have almost
-always found the volume of the spleen nearly equal, or at least the
-difference has not been very perceptible. Nevertheless, in other
-experiments I have seen the spleen, under various circumstances,
-to show variations in its volume, but more particularly in weight;
-and this was the same during digestion as after that process was
-finished. From what has been said it appears, that if, whilst the
-stomach is empty, there is a reflux of blood to the omentum and
-spleen, it is less than has been commonly asserted. Moreover,
-during this state of vacuity, the numerous folds of the mucous
-membrane of this viscus leaving it, as we have before said, almost
-as much extent of surface, and consequently of vessels, as during
-its plenitude, the blood must circulate there nearly as freely as
-when the viscus is in a contrary state; it has therefore no real
-obstacles; the only impediment is in consequence of the tortuous
-direction the vessels are then thrown into. Now this obstacle is
-easily surmounted, since the vessels suffer no constriction or
-diminution of calibre by the contraction of the stomach.
-
-51. As respects the other hollow organs, it is difficult to examine
-the circulation of their adjacent viscera during their plenitude
-or vacuity; for their vessels are not superficial, as in the
-omentum, or insulated, as in the spleen; therefore, to decide
-this question concerning them, we can only observe the state of
-the mucous membranes upon their internal surface. Now they have
-always appeared to me as red during the contraction as during the
-dilatation of the organs. Finally, I give this only as a fact,
-without pretending to draw any inference from it opposed to the
-common opinion. It is, in fact, possible, that though the quantity
-of blood be always nearly the same, the rapidity of the circulation
-may increase; and consequently, in a given time, more of this
-fluid will be sent there during the plenitude of the viscera. This
-appears to be necessary for the secretion of the mucous fluids,
-which are then more abundant.
-
-
-
-
-SECTION VI.
-
-OF THE VARIATIONS IN THE ORGANIZATION OF MUCOUS MEMBRANES IN
-DIFFERENT REGIONS.
-
-
-52. The assemblage of the epidermis, corps papillaire, chorion,
-glands, and vessels, constitutes in the mucous membranes their
-intimate organization, which presents very considerable variations
-in the different regions in which they are examined. I shall point
-out only the principal of them; for in no different parts do these
-membranes present the same appearance, and in order to describe all
-their differences they should all be examined.
-
-53. One of these variations is that which the aspect of mucous
-membranes presents at their origin, when compared with their
-appearance in the more remote parts of the organs. Compare, for
-instance, the surface of the glans, the inner surface of the
-lips, the orifice of the urethra, &c., with any portion of the
-inner surfaces of the stomach, intestines, &c. In the first the
-corps papillaire will be seen slightly marked, and offering no
-villous character, the epidermis thick, very distinct, and easily
-separated, the chorion very evident, the vessels rather less
-superficial, the mucous glands numerous and very large, more
-especially in the mouth; in the other characters almost opposite
-will be observed; we should say, that the mucous membranes have
-at their origin a structure of a middle kind between the skin and
-their deeper portions.
-
-54. Another variation of structure, not less striking, is that
-which is met with in that portion of mucous surface which lines
-the sinuses. Here it has more redness, and an extreme tenuity;
-the three layers cannot be distinguished; and although there is a
-considerable secretion of mucous fluids, there are no perceptible
-mucous glands. Such are the characters of those portions of the
-pituitary membrane, which are considered as adapted to augment the
-sensation of smell, but which do not perform that function in the
-manner generally understood. In fact, the instant when an odour
-enters the nose, having the air for its vehicle, it cannot at once
-pass into the sinuses, because the orifices by which these cavities
-communicate with the nose are very small; but it enters gradually,
-impregnates all the air which they contain, and not being able to
-escape readily, for the same reason that rendered its entrance
-difficult, the sensation is prolonged, which on the general
-pituitary membrane is soon dissipated by the action of the fresh
-air. Thus therefore the pituitary membrane is destined to receive
-the impressions of odours, and its extensions into the cavities of
-the sinuses to retain them.
-
-55. With regard to the particular structure of that portion of
-mucous membrane which lines the sinuses I remark, that it is
-absolutely the same as of that which is spread over the surface
-of the internal ear, with the exception of a still more delicate
-tissue. All anatomists call this membrane the periosteum of the
-bony covering of the internal ear. The following considerations
-prove that it is not a fibrous membrane, analogous to that which
-covers the bones, but a mucous layer, like that of the sinuses. (1)
-It is evidently seen to be a continuation of the pituitary membrane
-by the medium of the Eustachian tube. (2) It is found to be
-habitually moist with a mucous fluid, which is discharged through
-that tube, a property foreign to fibrous membranes, both of whose
-surfaces are always attached to some parts of the animal structure.
-(3) No fibre can be distinguished in it. (4) Its spongy appearance,
-though whitish, its softness, the readiness with which it gives way
-to the least agent directed against it, with a view to tear it,
-form a character not to be found in any part of the periosteum.
-
-56. I pass over the other variations of structure in mucous
-membranes in their different regions; in all they have real
-differences. I observe only, (1) That these variations distinguish
-them from serous membranes, whose aspect is everywhere the same, as
-may be seen by comparing the pericardium with the peritoneum, &c.
-(2) The sensibility of mucous membranes varies in a very peculiar
-manner in their different portions: thus an emetic irritates the
-stomach, but not the conjunctiva; the pituitary membrane perceives
-only odours; the mucous surface of the tongue flavours, &c. On the
-contrary, the contact of all kinds of bodies with the naked serous
-membranes produces phenomena exactly analogous.
-
-
-
-
-SECTION VII.
-
-OF THE VITAL POWERS OF THE MUCOUS MEMBRANES.
-
-
-57. The sensibility of mucous membranes is one of the principal
-characteristics that distinguishes them from other analogous
-organs. This power, which belongs to organic bodies, is variable
-in every part, prompt to develop itself in some parts, under
-the influence of the least excitement, roused with difficulty
-in others, present in every part, liable to proceed by means
-of inflammation from the most obscure state to the last degree
-of intensity--this power is here remarkable for features very
-analogous to those which it presents in the cutaneous surface (to
-which, as we have stated, the mucous surface has great traits of
-resemblance) as respects its structure. It is to this analogy of
-sensibility that we must refer a crowd of phenomena, which are
-alternately exhibited in an inverse order upon both surfaces. I
-shall now point out some of these phenomena in succession.
-
-58. (1) When the temperature of the surrounding air deadens the
-sensibility of the cutaneous organ, by contracting its tissue, the
-sensibility of the mucous surface receives a remarkable increase
-of energy. Observe why in winter, and in cold climates, where the
-functions of the skin are singularly limited, all those of the
-mucous membranes are in proportion augmented; thence arises a more
-evident pulmonary exhalation, the internal secretions are more
-abundant, digestion is more active and more ready to operate,
-consequently the appetite is the more easily excited. (2) When,
-on the contrary, the heat of the climate, or of the season, &c.
-relaxes and opens the cutaneous surface, we should say, that the
-mucous surface is in proportion constricted: during summer, in
-the south, &c. there is a diminution in the internal secretions,
-the urine for instance; a tardiness in the digestive phenomena
-by a default in the actions of the stomach and intestines, and
-the appetite is slow in returning. (3) The sudden suppression of
-the functions of the cutaneous organ often determines a morbid
-increase of action in those of the mucous membrane. Cold air, which
-checks the perspiration, frequently produces colds and catarrhs,
-affections which are marked by the sensibility and increased action
-of the mucous glands. (4) In various affections of the mucous
-membranes, baths, which relax and determine to the skin, produce
-beneficial effects.
-
-59. The foregoing considerations evidently establish the influence,
-which the vital powers of the skin have over those of the mucous
-membranes. Others, not less important, demonstrate the reciprocal
-dependence in which the skin is found with the same membranes, as
-respects their vital powers. (1) During digestion, when the mucous
-fluids are poured out in abundance into the stomach and intestines,
-when, consequently, the mucous membranes of the alimentary canal
-are in high action, the fluid of insensible perspiration is
-evidently diminished, according to the observation of Santorius:
-it is very small in quantity three hours after a meal, so that
-the action of the cutaneous organ is visibly less energetic. (2)
-During sleep, when all the internal functions become more marked
-and are in full action, at which time the sensibility of the mucous
-membranes is consequently highly excited, the skin appears to be
-seized by a manifest debility--a debility, which is evinced by
-the cold which it experiences when the animal reposes at night
-uncovered, and by its want of susceptibility of various impressions.
-
-60. The sensibility of the mucous membranes, like that of the
-cutaneous organ, is essentially submissive to the immense influence
-of habit, which, tending incessantly to blunt the acuteness of the
-sensations of which they are the seat, reduces the pain and the
-pleasure that we receive through them equally to indifference,
-which is, as some say, the middle state.
-
-61. I say, in the first place, that habit reduces the painful
-sensations, which take place on mucous membranes, to indifference.
-The presence of the catheter, which is passed up the urethra
-for the first time, is cruel the first day, painful the second,
-inconvenient the third, scarcely felt the fourth; pessaries
-introduced into the vagina, bougies into the rectum, tents in the
-nasal fossæ, the canula in the nasal canal, produce, in different
-degrees, the same phenomena. It is upon this remark that is founded
-the possibility of introducing instruments into the trachea to
-aid respiration, and into the œsophagus to afford artificial
-deglutition. This law of habit may even transform a painful into a
-pleasant impression; of this fact the use of snuff, tobacco, and
-various kinds of food, furnish us with remarkable examples.
-
-62. In the second place I observe, that habit produces indifference
-to those sensations on the mucous membranes which were at first
-agreeable. The perfumer placed in a fragrant atmosphere, and the
-cook, whose palate is constantly affected by delicious flavours, do
-not experience, in their professions, the exquisite pleasures that
-they prepare for others. Habit may even change pleasant sensations
-to painful ones, as in the preceding paragraph we saw it changed
-painful to pleasing sensations. I observe, further, that this
-remarkable influence of habit is exercised only over sensations
-produced by simple contact, and not over those produced by real
-lesion of the mucous membranes: thus it does not ameliorate the
-pain produced by stone in the bladder, nor that which attends
-polypus in the uterus.
-
-63. It is to this power of habit over the vital energies of
-the mucous membranes that we must, in part, refer the gradual
-diminution of their functions which accompanies advancing age. All
-is susceptibility in the infant: in old age all is dull. In the one
-the very active sensibility of the alimentary, biliary, urinary,
-and salivary mucous surfaces, is that which principally produces
-that rapidity with which the digestive and secretory phenomena
-succeed each other. In the other this sensibility, weakened by the
-habit of contact, does not so closely connect the same phenomena.
-
-64. Does not the following remarkable modification of the
-sensibility of the mucous surfaces depend upon the same cause,
-_viz._ that at their origin, as on the pituitary membrane, the
-glans, the anus, &c., they give us the sensations of bodies with
-which they are in contact, and that they do not produce this
-sensation in the deeply seated organs which they line, as the
-intestines, &c.? In the interior of these organs this contact is
-always uniform; the bladder is in contact with the urine only,
-the gall bladder with the bile, the stomach with the aliments
-masticated and reduced to an homogeneous, pulpy paste, whatever
-may be their diversity. This uniformity of sensation prevents
-perception, because, in order to perceive, we must compare, and
-here two terms of comparison are wanting. Thus the fœtus has no
-sensation of the liquor amnii: the air is also very irritating at
-first to the new-born infant, but at length it is not felt. On the
-contrary, at the origins of mucous membranes exciting agents vary
-every instant: the mind can, therefore, perceive their presence,
-because it is able to establish relations between their various
-modes of action. What I say is so true, that if in the interior of
-the organs the mucous membranes be in contact with a foreign body
-differing from that which is habitual to them, they transmit the
-sensation of it to the mind; instruments introduced into bladder or
-stomach are examples of it. Fresh air, which in very hot weather is
-suddenly introduced into the trachea, causes an agreeable sensation
-over the surface of the bronchi; but from habit we soon become
-insensible to it, and the perception ceases.
-
-65. It is very difficult to point out with precision the character
-of the tonic powers of mucous membranes, because, being almost in
-every part united to a muscular layer, we can hardly distinguish
-what belongs to the tonicity of the one from what depends upon the
-irritability of the other; or otherwise, if the mucous membranes
-be isolated, as in the nostrils, yet their attachment renders the
-phenomena of their tonic powers very obscure. Nevertheless, the
-action of the excretory ducts on their respective fluids, that
-of the gall bladder, and of the vesiculæ seminales, which are
-destitute of muscular attachments, and the spasmodic contraction
-of the urethra, which sometimes takes place when the sound is
-introduced, leave no doubt of the energy of this tonic power,
-doubtless similar in its various modifications to that which is
-observed in the cutaneous organ.
-
-
-
-
-SECTION VIII.
-
-OF THE SYMPATHIES OF MUCOUS MEMBRANES.
-
-
-66. I distribute the sympathies of mucous membranes, like those of
-most of the other organs, into three general classes. In the first
-class are ranked the sympathies in which irritation, on one part of
-the mucous surface, produces a sensation in a distant part. A stone
-in the bladder occasions pain at the end of glans; worms in the
-intestines excite an itching at the nose. Whytt has seen a painful
-affection induced over the whole side of the head by a foreign
-body in the ear; an ulcer in the bladder produces a pain in the
-superior parts of the thighs every time that the patient passes his
-urine.
-
-67. I refer to the second class those sympathies in which the
-irritation of one point on mucous surfaces produces irritability
-in a different structure; thus, too lively an impression on the
-pituitary membrane occasions sneezing; the irritation of the
-bronchi coughing; biliary concretions produce spasmodic vomiting;
-stones in the bladder occasion retraction of the testicle towards
-the ring. In all these cases there is contraction of the muscles
-produced by the irritation of the mucous surface, distant from the
-place in which that contraction occurs.
-
-68. The last class of the sympathies of mucous membranes embraces
-those in which the irritation of any part of their extension
-determines elsewhere the exercise of their tonicity. Here we must
-refer to what we have said upon glandular action being augmented
-by the irritation of the extremities of the excretory ducts. Thus
-it is evident, that the increase of the tonic power of the parotid
-for the secretion of the saliva, and of its excretory duct in order
-to transmit it, when the extremity of this duct is irritated by
-food, sialogogue medicines, &c.,--it is evident, I say, that this
-augmentation is a phenomenon purely sympathetic. We may designate
-each of these three classes by the name of the vital power which
-they bring into action, calling the first sympathy of sensibility;
-the second, sympathy of irritability; and the third, sympathy of
-tonicity.
-
-69. This manner of classing the sympathies is entirely borrowed
-from the state of the vital powers, of which they are but irregular
-modifications, and only aberrations, still unknown in their
-nature. Nevertheless it is subject to very great inconveniences:
-yet it appears to me to be preferable to that of Whytt, who simply
-follows the order of the regions; and even to that of Barthy, who,
-more methodical, examines them successively in the organs connected
-by systems, in those which are insulated, and in those situated in
-symmetrical halves of the body.
-
-
-
-
-SECTION IX.
-
-OF THE FUNCTIONS OF MUCOUS MEMBRANES.
-
-
-70. I have already examined many of the functions of mucous
-membranes. I have considered them (1) As one of the grand
-emunctories of the animal economy. (2) As performing the same
-functions with respect to heterogeneous bodies, which may be within
-our organs, as the skin does with regard to the bodies with which
-it may be in contact. (3) As facilitating the passage of foreign
-bodies by means of the mucous fluid by which they are lubricated.
-It remains for me to examine three questions much agitated at
-this time. (1) If the mucous membranes have any influence over the
-redness of the blood. (2) If they exhale. (3) If the absorbents
-arise from them; and if absorption consequently takes place there.
-
-71. The remarkable redness of these membranes, the analogy of
-respiration, during which the blood becomes changed in colour
-through the mucous surface of the bronchi, the well-known
-experiment of a bladder filled with blood and placed in oxygen gas,
-by which this fluid becomes also changed in colour,--have led to
-the belief, that the blood, being separated from the atmospheric
-air merely by a very fine pellicle on certain mucous surfaces,
-as the pituitary membrane, the palatine, the glans, &c., would
-there also take a brighter red colour, either by parting with a
-portion of carbonic acid gas, or by combining with the oxygen of
-the atmosphere, and that these membranes thus fulfilled functions
-accessory to those of the lungs. The experiments of Jurine upon the
-cutaneous organ, experiments adopted by many celebrated physicians,
-appear also to favour the reality of that conjecture.
-
-72. Observe the experiment that I have tried, in order to ascertain
-the validity of that fact. Through a wound in the abdomen I drew
-out a portion of intestine, which I tied at one point. I then
-returned it, keeping back a part, which I punctured, and introduced
-into it sufficient atmospheric air to distend all that portion of
-the bowel between the ligature and the orifice. I then confined the
-air by another ligature, and reduced the whole. At the end of an
-hour the animal was opened. I compared the blood of the mesenteric
-veins, which arise from that portion of intestine distended by
-air, with the blood of the other mesenteric veins arising from
-the remainder of the canal: no difference of colour could be
-observed: the internal surface of the inflated intestine did not
-exhibit a brighter red. I expected to obtain a more marked effect
-by repeating the same experiment on another animal with oxygen
-gas, but I did not perceive any variation in the colour of the
-blood. As on the mucous membranes, which are ordinarily in contact
-with the air, this fluid is constantly renewed, and is agitated
-by a perpetual movement, I tried to produce the same effect in
-the intestines; for which purpose I made two openings into the
-abdomen, through each of which I drew a portion of the intestinal
-tube. I opened these two portions, adapting to one the tube of a
-bladder filled with oxygen gas, and to the other that of an empty
-bladder. I then pressed the full bladder so as to make the oxygen
-gas pass into the empty one through the intermediate portion of
-intestine which was in the abdomen, so that the warmth there might
-encourage the circulation. The oxygen gas was in this manner sent
-many times from one bladder to the other, making a current through
-the intestine, which from its contraction was more difficult than
-it at first appeared to be. The abdomen was then opened, but no
-difference was found between the venous blood returning from that
-portion of the intestine, and that which flowed from the other
-parts of the canal. The superficial situation of the mesenteric
-veins, which are covered by only a fine transparent lamina of
-peritoneum, and their volume when the animal is not fat, render
-these comparisons very easy to be made.
-
-73. I think, that from what occurs in the intestines we cannot
-infer what takes place in the pituitary and palatine membranes,
-&c.; because, although analogous, their organization may be
-different. In these parts we cannot examine the venous blood
-returning from them, as in the intestines: but, (1) If we consider,
-that in animals, which have for some time respired oxygen gas, the
-mucous membrane of the fauces does not exhibit any increase of
-redness; (2) If we bear in mind, that the lividity of different
-parts of this membrane, in those asphyxias which are produced by
-carbonic acid gas, is not occasioned by the immediate contact of
-this gas with the membranes, but by the reflux towards the surface,
-of the venous blood which cannot pass through the heart, as occurs
-in submersion, as demonstrated by Godwin, and as takes place in
-all those cases in which the blood, previous to death, has found
-difficulty in passing through the lungs; (3) If we remark lastly,
-that in these circumstances the contact of the air, after death,
-does not alter the lividity that the venous blood gives to the
-mucous membranes, although the skin is then more permeable to
-every kind of æriform fluid;--we shall see that we must at least
-suspend our judgment, respecting the colouring of the blood through
-mucous membranes, until farther observations shall have decided the
-question.
-
-74. Observe another experiment, which may throw more light still
-upon the subject. I have distended the peritoneal cavity of
-different Guinea pigs with carbonic acid gas, with hydrogen gas,
-with oxygen gas, and with atmospheric air, to see if I could
-obtain, through a serous membrane, what I had not been able to
-effect through a mucous surface. In these experiments I have found
-no difference in the colour of the blood of the abdominal system:
-it was the same as in fresh animals of the same kind, that I
-always used to compare with those on which the experiments were
-made.
-
-75. I believe, nevertheless, that I have observed many times, both
-in frogs and in animals with warm and red blood, such as cats and
-Guinea pigs, that the infiltration of oxygen gas into the cellular
-tissue gives, after a certain time, a brighter colour to the blood
-than this fluid presents in the artificial emphysemas which may
-be produced by carbonic acid gas, hydrogen gas, or by atmospheric
-air, in which circumstances the blood differs very little in colour
-from its natural shade. But in other cases oxygen gas has had no
-influence over the colour of the blood; so that, notwithstanding
-the many experiments that have been made on this point, I cannot
-state any general result. It appears, that the tonic powers of
-the cellular tissue, and of the coats of the vessels which ramify
-in it, receive a very varied influence from the contact of the
-gases, and that, according to the nature of that influence, the
-fibres contracting and becoming more or less firm render these
-parts more or less permeable, both to the æriform fluids, which
-have a tendency to escape from the blood to unite with that of the
-emphysema, and to this last fluid, if it tends to combine with
-the blood. This will doubtless explain the variations that I have
-observed.
-
-76. Do the mucous surfaces exhale? The analogy of the skin would
-seem to lead to the belief of it; for it appears well proved, that
-the perspiration is not a transudation by the inorganic pores of
-the cutaneous surface, but a true transmission by vessels of a
-particular nature, and continuous with the arterial system.
-
-77. It appears, at first, that the pulmonary perspiration which
-takes place on the surface of the bronchi, which has such
-connection with that of the skin, which increases or diminishes
-according to the decrease or augmentation of the other, and
-of which the composition is apparently of the same nature--it
-appears, I say, that the pulmonary perspiration is produced, at
-least in part, by the system of exhalent vessels; and that if the
-combination of the oxygen of the air concurs with the hydrogen of
-the blood to produce it, during the act of respiration, it is but
-in a very small quantity, and for that portion only which is purely
-aqueous. It is necessary to observe further on this subject, that
-the dissolution of the mucous fluid, which lubricates the bronchi,
-in the air that is constantly inspired and expired, furnishes a
-considerable portion of that vapour which rises from the lungs, and
-which is insensible in summer, but very apparent in winter.
-
-78. The intestinal juice, that Haller has particularly considered,
-but which appears to be less in quantity than he had estimated,
-the gastric juice, and that of the œsophagus, are very probably
-disposed of by way of exhalation on their respective mucous
-surfaces; but in general it is very difficult to distinguish with
-precision, in these organs, what belongs to the exhalent system
-from what is furnished by the system of mucous glands, which, as we
-have said, are everywhere subjacent to them. Thus we constantly see
-the mucous fluids of the œsophagus, stomach, and intestines, mix
-themselves with the other fluids of these parts.
-
-79. That mucous membranes absorb is evidently proved by the
-absorption of the chyle upon the intestinal surfaces, of venereal
-virus upon the glans and urethra, of variolous poison which is
-sometimes rubbed upon the gums, of the serous portions of the
-bile, of the urine, and of the semen, when they remain in their
-respective reservoirs. When, from paralysis of the fleshy fibres
-which terminate the rectum, the fæces accumulate at the extremity
-of that intestine (a very common case in aged persons, and of which
-Desault has cited many instances), these accumulations frequently
-become hard, probably from the absorption of their juices, which
-are obstructed there. We have many cases in which the urine has
-been almost entirely absorbed by the mucous surface of the bladder,
-when there has been absolute obstruction in the urethra. Whatever
-may be the mode of this absorption, it appears that it is not
-performed in a constant, uninterrupted manner, like that of the
-serous membranes, in which the exhalent and absorbent systems are
-in a continual alternate action; but that it occurs only under
-certain circumstances, of which perhaps the greatest part are not
-in the natural order of the functions. Finally, we have yet fewer
-data respecting the mode of mucous absorption than on that of
-cutaneous absorption: we confess it is very little understood, and
-many even question its existence.
-
-
-
-
-SECTION X.
-
-REMARKS ON THE AFFECTIONS OF MUCOUS MEMBRANES.
-
-
-80. It is not my design to examine the affections of mucous
-membranes; I shall notice only some phenomena, which in these
-affections I believe deserve a particular attention, and the
-explanation of which I propose to physiological physicians.
-
-81. Why do mucous membranes seldom contract adhesions from
-inflammation, since that occurs so frequently in serous surfaces
-under the same circumstances? Why does not the internal surface
-of the inflamed stomach, intestines, or bladder, adhere in its
-various portions like the pleura, tunica vaginalis, testis, &c.
-
-82. Why, in inflammations of mucous membranes, is there an abundant
-flow of that fluid which habitually moistens them, and which
-constitutes the different kinds of catarrhs, whilst the source of
-the fluid that exhales from serous membranes is generally dried up
-in analogous cases?
-
-83. Why do polypi, a kind of affection peculiar to mucous
-membranes, seldom arise but at the origins of these membranes in
-the vicinity of the skin, as in the nose, pharynx, vagina, &c., and
-not in their more internal portions, as in the stomach, intestines,
-&c.? Does this arise from the peculiarity of the texture that I
-have shown mucous membranes to have in the vicinity of those places
-where they arise from the skin, or must we attribute this fact to
-the more numerous causes of irritation which act upon the origins
-of these cavities?
-
-84. Are not aphthæ an isolated inflammatory affection of the glands
-of the mucous membranes, whilst catarrhs are characterized by a
-general inflammation of all the parts of these membranes?
-
-
-THE END.
-
-
-CHARLES WOOD, Printer,
-
-Poppin's Court, Fleet Street, London.
-
-
-
-
-FOOTNOTES:
-
-[A] The following questions have been much disputed: Is there a
-cystic and an hepatic bile? Is the one of a different nature from
-the other? Does their quantity increase or vary? &c. Contrary,
-and even opposite, opinions have been supported by numerous
-experiments made upon living animals, as Haller as well observed.
-These experiments, though at first sight contradictory, in reality
-are not so, as I have had the opportunity of convincing myself, by
-repeating them in the different stages of digestion, and during
-the abstinence of the animal, which previously had never been done
-with precision. The following are what I have observed in dogs
-that I have used in my experiments. (1) During abstinence, the
-stomach and the small intestines being empty, yellowish clear bile
-was found in the hepatic duct and ductus communis choledochus; the
-surface of the duodenum and jejunum were stained by a bile which
-had the same appearance; the gall bladder was very much distended
-by a greenish bitter bile, which was deeper in colour and more in
-quantity, according to the length of the abstinence. (2) During the
-gastric digestion, which may be prolonged for a sufficient length
-of time by giving the dog large pieces of meat, which he swallows
-without chewing, appearances were similar. (3) At the commencement
-of intestinal digestion, the bile in the hepatic duct was always
-found yellowish; that of the ductus communis choledochus deeper in
-colour; the gall bladder not so full, and its bile becoming already
-more clear. (4) Towards the end of digestion, and immediately
-after it, the bile of the hepatic duct, of the ductus communis
-choledochus, that contained in the gall bladder, and that which was
-spread over the duodenum, were exactly of the same colour as the
-common hepatic bile, a clear yellow, having but little bitterness.
-The gall bladder was but half full; it was not contracted, but
-flaccid.
-
-These observations, repeated a great number of times, evidently
-prove, that such is the manner in which the bile flows during
-abstinence and during digestion. (1) It appears that the liver is
-continually separating from itself a sensible quantity of bile,
-which increases during digestion. (2) That which is secreted during
-abstinence is divided between the intestine, which is always found
-coloured with it, and the gall bladder, which retains it without
-transmitting any portion of it through the cystic duct, and where,
-thus retained, it acquires a deeper colour and a character of
-acrimony, necessary, without doubt, to the digestion which is soon
-to follow. (3) When the food, having been digested by the stomach,
-passes into the duodenum, then all the hepatic bile, which was
-before divided, flows into the intestine, and even in greater
-abundance; the gall bladder also pours that which it contains
-upon the alimentary pulp, and with which it is then found quite
-incorporated. (4) After the intestinal digestion the hepatic bile
-diminishes, and begins to flow, part into the duodenum and part
-into the gall bladder, where, being then examined, it is clear and
-in small quantity, because it has not yet had time either to become
-coloured, or to collect.
-
-There is, therefore, this difference between the two kinds of bile,
-that the hepatic flows in a continual manner into the intestine,
-and the cystic, during the absence of digestion, flows back into
-the gall bladder; and whilst that function is going on it passes
-towards the duodenum; or rather it is always the same fluid, of
-which one part preserves the character it has when it leaves the
-liver, and the other part undergoes a change in the gall bladder.
-The difference of colour in the cystic bile, according to the time
-that it has remained in the gall bladder, is analogous to the
-colour of the urine, which becomes deeper as it is retained longer
-in its receptacle.
-
-[B] The bile in the gall bladder, the urine in the bladder, and
-the semen in the vesicula seminales, are certainly absorbed; but
-it is not the fluid itself that re-enters the circulation, but
-only its finest parts, some of its principles that we are not well
-acquainted with, probably its aqueous or lymphatic portion. This
-does not resemble the absorption in the pleura and other analogous
-membranes, in which the fluid rejoins the blood in the same state
-as it left it.
-
-[C] This is a necessary consequence of the disposition of the
-vascular system of the stomach. The arteria coronaria ventriculi
-superior being situated transversely between the stomach and the
-omentum, and furnishing branches to both, it is evident, that when
-the stomach, by separating the duplicatures of the omentum, lodges
-itself between them, and this in applying itself over the stomach
-becomes shortened, the branches that it receives from that artery
-cannot in the same manner apply themselves to it. To effect this
-it would be necessary, that they should proceed from the one to
-the other without the intermediate trunk that cuts them at right
-angles; then the stomach, by distending itself, would separate them
-in the same way that it does the omentum, and would lodge between
-them, instead of pushing them before it with their common trunk,
-and folding them upon themselves.
-
-
-
-
-  TRANSCRIBER'S NOTE
-
-  Italic text is denoted by _underscores_.
-
-  Obvious typographical errors and punctuation errors have been
-  corrected after careful comparison with other occurrences within
-  the text and consultation of external sources.
-
-  Except for those changes noted below, all misspellings in the text,
-  and inconsistent or archaic usage, have been retained. For example,
-  newly-born, newly born; circumvolutions; atmospherical.
-
-  Pg v (TOC), page '101' replaced by '98'.
-  Pg 54, 'the mach, small' replaced by 'the stomach, small'.
-  Pg 57, 'membranes is spread' replaced by 'membrane is spread'.
-  Pg 81, 'OF THE SYMPATHY' replaced by 'OF THE SYMPATHIES'.
-  Pg 86, 'fine pelicle' replaced by 'fine pellicle'.
-  Pg 90, 'those asphyxies' replaced by 'those asphyxias'.
-
-
-
-
-
-End of the Project Gutenberg EBook of Treatise on the Anatomy and Physiology
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