Section Viii. the Lungs and Bronchial Tubes.

The pathological conditions of the lungs, may be arranged as follows:—Inflammation and its results, hepatization, suppuration, abscess, gangrene, hæmorrhage, pulmonary apoplexy, emphysema, tubercular disease, morbid growths, and parasitical animals.

When in a healthy condition, the lungs will present the following appearance:—Upon opening the chest, there will be a more or less complete collapse of both organs, partly from atmospheric pressure, and partly from the elasticity of the lung tissue. They will then have a shrunken, shrivelled appearance, crepitating under pressure, and have an ashen gray color. If inflated, the surface becomes smooth and shining, showing an indistinct outline of the lobules, which, with the dark pigmentary matter seen here and there, gives the surface more or less of a mottled appearance.

Where pleurisy had previously existed, there may be adhesions preventing the collapse of the lungs, until these have been broken up. When cut into, healthy lung tissue has a soft, spongy character, the upper portions will be quite destitute of blood, while the posterior portions may be more or less filled with that fluid from gravitation, giving them a dark congested appearance.

Inflammation and its Results.

=Pneumonia=, or inflammation of the lungs, may affect both the air cells, when the latter become filled with fibrinous exudations, and the connective areolar tissue, which then become increased in quantity.

The following characters present themselves, corresponding to the three recognized stages of the disease:—First, congestion; second, red hepatization; third, gray hepatization or softening.

=Congestion.= From the peculiar structure of the lungs, in connection with the free circulation through the same, these organs are peculiarly liable to the several forms of congestion. In many cases of death, without any original disease of the lungs, there will be a tendency for these organs to become loaded with blood, giving rise to post-mortem appearances, often with difficulty distinguished from those of a pathological origin. In this post-mortem, or, as it has been called hypostatic congestion, the posterior and inferior portions of the lungs are chiefly affected, as the blood after death, obeying the law of gravitation, sinks to the lowest point. The congested portion presents a dark red color, and though firmer than other portions, crepitates under the finger and floats in water, the latter circumstance serving to distinguish this form of congestion from that of an inflammatory origin. If the congestion be confined to one lung, or to the anterior parts of either, we may safely attribute it to a pathological cause.

In all cases of congestion, upon opening the chest, although there may be no adhesions, the lung does not collapse, or does so feebly. When cut, it is found to be loaded with blood, and upon pressure, much bloody serum escapes, while the divided bronchial tubes will be found filled with frothy mucus.

=Red Hepatization.= This condition of the lungs soon follows that of congestion. The change is a gradual one, and is first marked by an effusion of serum and coagulable lymph into the connective tissue and air cells, thus rendering the lungs more solid, while as the change becomes complete, the blood itself, which had during the congestive stage been confined to the vessels, is now found extravasated into the interstices of the tissues. The portion of the lung thus affected is not only of a dark red or violet color, but solid, firm, does not crepitate, sinks when thrown into water, and when cut and washed, the section shows patches of a rough, granular aspect, totally different from that of healthy lung tissue. The pleura in this condition may be wholly unchanged, even though the solidification may have been of long standing.

=Gray Hepatization=, which characterizes the third stage of pneumonia, is known by the lung presenting a firm, semi-solid, inelastic, and more or less incompressible character. Failing to collapse, the lung is found more or less completely filling the chest. The pleura will generally present evidences of inflammation in the presence of patches of lymph and more or less points of adhesions. The upper lobe may be soft and compressible, while the lower is solid from hepatization. When divided with the knife, the substance is found of a gray, red, or dirty yellow color; compact, but friable and easily broken down with the fingers, while the smaller bronchial tubes are filled with fibrinous plugs. Bloody purulent matter, with much turbid serous fluid, will ooze from the cut surfaces. Pus globules will be detected in the escaping fluids by a microscopic examination.

Resolution of a hepatized lung, consists in the gradual softening of the effused substances within the smaller bronchial tubes and air cells, and the discharge of the same by cough and expectoration.

Inflammation of the lung usually commences in the lower lobe, and while the disease here may extend to complete hepatization, the middle lobe may be found merely congested, while the upper is quite healthy. Inflammation may attack one or both lungs. In the former case it is known as single, and in the latter as double pneumonia. From an examination of a large number of cases, it has been ascertained that inflammation of the right lung is more frequent than that of the left in the proportion of about three to one, and that single pneumonia is more common than double pneumonia in the ratio of six to one.

Pneumonia is sometimes divided into Catarrhal and Croupous. In the former, the exudation contains little or no fibrinous matter, while the bronchial mucous membranes are also involved, the disease at the same time being confined mostly to the lobules of the lungs. In the croupous form, the exudation contains a large proportion of fibrine, and the disease usually involves the greater part of a lobe, or may extend to the whole of one or both lungs.

Both forms of the disease may run through the three stages of congestion, red and gray hepatization.

A peculiar form of inflammation of the lungs, found mostly in children and young persons, and usually chronic in character, has been described as

Lobular Pneumonia. The inflammation here being confined to the lobules, these, after the disease is perfectly developed, present the appearance of a multitude of rounded nodules, of the size of small nuts, scattered through the substance of the lungs. The exterior of these is reddish, firm, and vascular, while the interior is of a grayish color, containing effused lymph, with more or less purulent matter.

This form of pneumonia being frequently associated with diseases of the joints and bones, as well as with inflammation and ulceration of the glands of the intestines, it has been considered as depending upon a strumous diathesis, and as, in fact, but the early stage of tubercular consumption. Seldom proving fatal in the early stage, or before the disease has extended to the whole substance of the lung, and perhaps resulted in the formation of cavities, we much less frequently meet with this form of pneumonia in post-mortem examinations.

=Suppuration and Abscess.= Gray hepatization must be looked upon as a form of suppuration of the lungs; as the purulent-looking fluid found infiltrating the tissues, filling the air cells and smaller bronchial tubes, upon a microscopic examination, is found containing undoubted pus globules. This, however, is not an abscess, the matter not being confined within a cavity, but diffused through the tissues of the part. That a distinct abscess of the lungs may form, as a result of pneumonia, is generally admitted, though they are usually small and confined to the lower lobes. From softening of tubercular masses, abscesses not unfrequently form in any portion of the lungs. That they do not occur more frequently in pneumonia, may result from the fact that the disease often proves fatal by suffocation, before there has been time for it to have reached the suppurative stage.

The pleura over the seat of the abscess will generally be found much thickened, and frequently adherent to the opposite walls of the chest. Pulmonary abscess may be wholly discharged by expectoration—the cavity communicating with the bronchial tubes—or it may discharge into the pleural cavity, or when adhesions have first formed, it may work its way between the ribs, and the matter escape upon the surface of the body.

=Metastatic or Secondary Abscess.= This form of abscess in the lungs, is well understood to be the result of suppuration in some distant part or organ, which, being attended with phlebitis of the part, purulent matter is introduced into the circulation, and thus conveyed to the lungs or perhaps the liver. This original suppuration may be at the uterus after delivery, or from a fistulo in ano, psoas abscess, or any other similar affection.

From the fact, probably, that the whole volume of the blood flows through the lungs, at each round of the circulation, these organs are more frequently affected with this form of abscess than any other, it occurring next in frequency in the liver. These abscesses may be recognized as spots of yellow pus, varying in size from a pin’s head to a walnut, generally situated near the surface of the organ and surrounded by a dark, well defined layer of congested tissue, while beyond this, the structure is in a healthy condition. Several of such abscesses may be found in various parts of the lungs.

=Gangrene.= Gangrene of the lungs, rarely results from an attack of ordinary pneumonia, but appears more frequently to take place either as a concomitant of pestilential fevers in general, or as an accompaniment of certain cases of tubercular vomicæ of the lungs, or as a primary and peculiar species of inflammatory affection of those organs.

In the first instance, a patient suffering a severe form of typhoid fever, presents symptoms of pulmonary disorder, as hurried respiration, livid face, cough, first dry and soon moist, with thick orange-colored and finally dark or bloody and extremely offensive expectoration, and fetid breath. With these symptoms are generally associated great feebleness, delirium, with tendency to gangrene of the extremities and prominent points of the hips, sacrum, etc.; and finally, with increased difficulty in respiration and fetor of breath, death ensues.

In the second case, a patient suffering from clearly recognized tubercular disease of the lungs, which has passed on to softening of tubercular masses, and the formation of vomicæ, has an aggravation of all his symptoms, accompanied with the expectoration of a highly offensive dark matter, plainly resulting from a gangrenous condition of the interior of a tubercular cavity.

In the third case, the disease comes on at first as an affection of the lungs. The attack commences either as pulmonary inflammation, or bronchial disease, or with spitting of blood with more or less pain in the chest. The patient becomes rapidly worse, the cough increasing, with reddish-brown or bloody sputa, and offensive breath. The countenance is anxious and livid, the eye heavy, sometimes wild and glaring. The fetid breath is not always an early symptom, but when it does appear, the disease in general tends rapidly to a fatal termination, although recovery sometimes takes place.

The appearances after death, in cases of gangrene of the lungs, are of two kinds, according as the disease is diffuse or circumscribed.

“In the first case, a mass of lung, two and a-half or three inches wide, but irregular in figure and outline, is converted into a soft, pulpy, dark, ash-colored substance, which, when it is handled or pressed by the fingers, falls down into a loose, moist mass, emitting a fetid, offensive odor, without trace of the usual structure of the lungs, except a few bronchial tubes, and blood-vessels, and shreds of filamentous tissue. This mass is generally bounded by, but it does not terminate abruptly in, healthy lung. It is soft, dingy, and infiltrated with a dark, ash-colored, dirty, serous liquor. Occasionally the surrounding portion of the lung is hepatized or infiltrated with blood or bloody serum; the bronchial tubes always contain much bloody, viscid mucus; and sometimes the pleura is reddened, covered with lymph or adhesions, and contains fluid in its cavity.”

The portion of the lung thus affected is usually within the lower or middle lobe, the upper portion being rarely involved.

In the second, or circumscribed form, a portion of the lung, generally near the surface, presents a dark-colored, hard patch, varying in size from a quarter, to a half-dollar piece or more, often quite circular, and bounded all round by healthy lung. This circular hard patch, which resembles closely an eschar produced by caustic potash, may adhere or be easily detached. In the latter case, it generally leaves a cup-like cavity, the surface of which is firm, granular, with the blood-vessels and bronchial tubes closed, and with the surrounding lung more softened, but generally presenting marks of pleurisy, pneumonia, and bronchitis all combined, which may be looked upon as an effort of nature to isolate and detach the diseased mass.

=Pulmonary Hæmorrhage=—Hæmoptysis. Discharge of blood from the lungs by coughing, may result from a variety of causes, among which may be mentioned: 1, mechanical shock or injury, as in falls or blows upon the chest; 2, inflammatory action within the lungs; 3, disease of the heart; 4, disease of the arteries; 5, tubercular deposition; 6, tubercular destruction, with ulceration of vessels.

In the first instance the expectorated blood may be copious or slight, according to the severity of the injury. If death soon results, an examination of the lungs will disclose one or more of the bronchial tubes filled with blood, which has plainly arisen from a rupture of some of the capillaries of the bronchial mucous membrane. The blood discharged in many cases of the early stage of consumption, and in young females after the suppression or retention of the menstrual flow, is from the same source.

Hæmorrhage from the lungs may also take place as a result of tubercular deposits. The presence of tubercular masses must necessarily produce more or less pressure on the adjoining vessels, interfering with the flow of the blood through the same, and thus inducing congestion, and even rupture of some of the capillary branches. Again, where tubercular masses have progressed to softening, and a cavity has been formed, the ulcerative process may open a large vessel, and death result in a few minutes from excessive hæmorrhage. A post-mortem will here show the cavity, as well as the bronchial tubes and trachea, filled with coagulated blood.

The blood expectorated during the early stage of an attack of pneumonia, is never copious, consisting mainly of streaks of blood through the saliva, while at a later stage, from being more uniformly diffused, it gives the peculiar rusty sputa characteristic of this disease. The post-mortem appearances have already been given under the head of pneumonia.

Certain forms of disease of the heart, as ossification of the mitral valves, with contraction of the orifice, or in hypertrophy of the left ventricle, with disease of the aortic valves, are frequently attended with hæmoptysis. In either case, the obstruction to the free circulation through the left side of the heart, must induce an over distension of the pulmonary veins, which, upon some unusual exertion, may readily result in extravasation through the bronchial mucous membrane, causing the bloody expectoration which takes place during life, or into the pulmonary connective tissue, giving origin thus to what is known as

=Pulmonary Apoplexy=. The post-mortem appearances in these cases, are as follows:—The portion of the lung involved, fails to collapse on opening the chest. It is firm, and of a dark red color; and when cut into, thick blood issues from the cut surfaces. The portion involved may include from one to four cubic inches. It will be found circumscribed with healthy lung tissue, and looks not unlike a clot of venous blood; these circumstances serving to distinguish it from hepatization, which terminates more or less gradually in sound lung.

While these hæmorrhagic effusions may, in many cases, cause early death by their size and number, in others, the clot may soften, the lung around become inflamed, or even gangrenous, resulting in the formation of an irregular cavity filled with dark, offensive, semi-fluid contents. In still other cases, where the clot is small, and in part within the air cells, it may soften and become absorbed or coughed up, and the air again enter the cells, or these may contract into a fibrous indurated mass.

=Emphysema.= Emphysema of the lungs, is usually described as of two forms—vesicular and interlobular.

Vesicular emphysema, consists essentially in a dilatation or over-distension of a greater or less number of air cells, resulting in giving the portion involved greater buoyancy in water, from diminished specific gravity, lessening the crepitation on pressure, preventing collapse on the opening of the chest, and rendering the affected portion more or less dry and bloodless. From the loss of elasticity, there will be during life, a difficulty in the lungs emptying themselves of air as they should, hence the patient will be subject to severe attacks of oppression upon the slightest aggravating cause. If one lung only is affected, the corresponding side becomes enlarged and less movable than the other; the adjoining viscera, as the heart or abdominal organs, are more or less displaced, the intercostal spaces swell out, and the ribs becoming more horizontal, give a barrel-shape to the chest, which is quite characteristic of emphysema.

This distension of the air cells, is more marked along the edges of the lungs, the vesicles at these parts being probably the least supported. Patches of dilated cells may be found, however, at other parts, which, if superficial, will project beyond the surface of the surrounding healthy portions, and appear like large bladders, from the coalescing of several vesicles.

This form of emphysema may be induced by any cause interfering with the ready escape of the air from any portion of the lungs, especially if accompanied with severe cough, as in many forms of bronchial disease, enlargement of the bronchial glands, etc.

Interlobular Emphysema, consists in an effusion of air into the connective or areolar tissue of the lungs, from a rupture of air cells or smaller bronchial tubes, or from the laceration of the lungs from a broken rib, when the air may accumulate in the pleural cavity, constituting pneumothorax, and may also be accompanied with emphysema of the chest, neck and head, from an escape of the air at the point of injury into the tissues of those parts. This form of emphysema may involve a large part or the whole of the lung, while the vesicular form is generally limited to definite portions. By disturbing the circulation through the lungs, emphysema is liable to induce dilatation of the right side of the heart.

From an evolution of gases within the lungs after death, we may have similar appearances to that above described, requiring some care to distinguish between the two. In the latter case, the general indications of decomposition, with the ease with which these distended vesicles may be emptied by pressure, will aid in determining the character of the case.

Tubercular Disease of the Lungs.

I shall not attempt to present here the various theories that have been promulgated as to the nature and origin of tubercle, contenting myself by giving a description of their anatomical characters, as presented in the several stages of tubercular disease.

Tubercle, or tubercular matter, may be described as consisting of a yellowish-white substance, opaque, friable and unorganized. It may be deposited in most of the tissues or organs of the body, but its more common seat is the free surfaces of mucous membranes, though often found in connection with the serous.

Tubercular deposits in the lungs, are not uniformly distributed through all parts of those organs, being in the large majority of cases confined to the upper and back part of the upper lobes, and in those cases where they are more or less distributed through the whole lung, they will be found more numerous and larger in those parts.

Tubercles may exist as fine points, not larger than a pin’s head, (miliary tubercle,) or the matter may accumulate in masses of the size of a kernel of corn, of a cherry, or of a robin’s egg. In other cases, the pulmonic exudation in some portion of the lung attending an attack of pneumonia, may become transformed into tubercular matter, having an irregular outline and no distinct boundary, (infiltrated tubercle.)

Tubercular matter is undoubtedly, in most instances, deposited within the air cells, so filling these, as to more or less interfere with the admission of the air, and giving greater density to the portion of lung involved. While the secreted matter is at first soft, or semi-fluid and partially translucent, it gradually acquires greater density, becomes opaque and cheesy in its character, and in all respects acting as a foreign body within the lungs. Sooner or later, the presence of tubercles will excite inflammation in the surrounding tissues. In this manner these bodies may become softened and their substance expectorated. If large numbers be aggregated together, the ulcerative process may completely destroy the tissues between, an abscess or vomica resulting.

In the early stage of the disease, before the inflammatory and ulcerative processes have been set up, the presence of tubercular matter, by interfering with the capillary circulation, may give rise to a hæmorrhage into the bronchial tubes, constituting the hæmoptysis so frequently present in this disease; while at a later period, from a destruction of some of the larger vessels from ulceration, a profuse and even fatal hæmorrhage may result.

Post-mortem Appearances.

In examining the lungs of those who have died after suffering the usual symptoms of pulmonary consumption, we shall find the upper portion of one or both lungs, more or less indurated, and occupied by one or more irregular shaped cavities, containing either air, or air and a quantity of viscid, puriform, dirty-looking fluid. Generally the apex of the affected lung, will be found firmly attached to the inner surface of the chest, by means of a thick, firm, false membrane, which unites the two layers of the pleura. In some instances, nearly or quite the whole surface of the lung will be found thus adhered, while the lobes will also be united by an interlobular false membrane. When the adhesions are confined to the upper portions of the lungs, the pleura covering the lower portion will frequently be found more or less rough from albuminous exudation, while a quantity of sero-purulent fluid will be found in the posterior part of the thoracic cavity.

The greater part of the upper lobe, may be found converted into one irregular cavity; more frequently, the upper lobe presents two or three, either isolated or communicating. The largest, when several are present, is most commonly in the upper portion of the lobe. When entirely or partially filled with matter, such cavities are usually termed vomicæ or abscesses, while when empty, they are generally called tubercular cavities or excavations.

In the lower part of the upper lobes, the cavities are few and small. The middle lobe of the right lung, rarely presents cavities, while the lower lobes of both lungs are entirely free. The whole of these parts, however, may be more or less indurated by the presence of hard, irregular shaped masses, the result, probably, of inflammatory action.

Tubercular cavities present a considerable variety, both in size and shape. They may not be larger than a pea, or bean, or may reach the size of an egg, or even of an orange. Always of an irregular shape, they often consist of one large cavity, communicating with two or three smaller ones. The interior will be found traversed by bands, or cords, passing in various directions, but generally taking a longitudinal course, and probably the remnants of blood-vessels and bronchial tubes.

The tissues immediately around a cavity, and forming its walls, will be found firm, inelastic, almost cartilaginous in character, and of a dark red, or brown color. The density of the structures is caused partly by tubercular deposits in the lung, and partly by inflammatory induration.

While tubercular disease of the lungs is almost universally fatal, there is reason to believe that, in a very small proportion of cases recovery has taken place, and the post-mortem appearances of the lungs have accorded with this view. These appearances may be described as follows:

We sometimes observe in examining the lungs of individuals who may have died from diseases of other organs, that the pleura covering the upper lobe of the lung, presents, at a certain point, a puckered, shrivelled appearance, with a leather-like feel, and with a rounded, firm mass beneath. Upon dividing the latter with the knife, the interior is found composed either of a soft substance like putty, or more frequently of a chalky nature. This is looked upon as a cicatrized or contracted vomica, the putty or chalk-like contents being the residuary matter of the softened tubercle, the thinner portion having been expectorated or removed by absorption. In some instances, these bodies are of almost a stony hardness, grating against the knife.

In other cases, cavities lined with a smooth, semi-cartilaginous false membrane are found, containing air only, and with dilated bronchial tubes opening into the same, no appearance of ulceration being visible, everything indicating that a tubercular mass had once occupied the cavity, its softening and expectoration having been followed by a healing of the inner surface.

Morbid Growths.

=Cancer.= Malignant disease of the lungs is by no means frequent, yet we have abundant evidence that cancer in its several forms may be developed in these organs. Colloid cancer, has been usually found more or less infiltrated through the substance of the lungs, while other forms appear in nodules or isolated tumors.

It is seldom, perhaps, that cancer exhibits itself as a primary affection of the lungs, the disease first appearing in some other part, and more frequently, it is said, in the bones or testicles; operation for the removal of cancer in these parts being very liable to be followed by an early development of the disease in the lungs or other internal organs. On the other hand, where the cancer is connected with any organ whose veins form a part of the portal system, as the stomach, spleen, pancreas, intestines, etc., the disease does not so frequently extend to the lungs, while in those cases the liver is more liable to become affected.

The encephaloid form of cancer, is that more frequently met. It may be connected either with the bronchial glands, when the diseased mass will be mainly confined to the mediastinum, and may consist of bodies varying in size from that of a cherry to that of a large apple, or, the disease may commence directly in the substance of the lungs, the tumor rapidly increasing in size, and crowding the lungs from their normal position. After death, the encephaloid mass may be found compressing the lungs into a very small space. The tumor presents the usual character of this disease, some of the lobules being soft and pulpy, or brain-like, others of a more firm, cheese-like consistence.

=Melanosis.= Two forms of melanotic deposits are observed in the lungs: one, true melanosis, and frequently associated with encephaloid disease; the other a deposit of carbonaceous matter from coal dust, smoke, etc., which has been inhaled during life, and distinguished as spurious melanosis.

True melanosis consists in a deposit of a dark pigmentary matter in the substance of the bronchial glands, found at the bifurcation of the trachea, and along the main bronchi. The glands are at the same time enlarged. The coloring matter may be solid, or slightly fluid, or pasty. At the same time the melanotic matter may be infiltrated to some extent into the substance of the lungs, or deposited in cysts within the same.

In spurious melanosis, the dark carbonaceous matter is diffused more or less through the whole lung, and may be seen distinctly through the pleura. The bronchial mucous membrane is more or less tinged with the same substance, and generally a quantity of black-colored fluid may be expressed from the cut surfaces.

=Hydatids.= Acephalocysts or animal hydatids, have not unfrequently been found in the lungs, and in several instances they have been discharged by expectoration.

These cysts vary in size from a cherry to an egg, and consist of a double membrane containing a limpid fluid within which other hydatids may be found, of the same character as the parent cyst. They may excite inflammation and suppuration in the tissues around, and thus become discharged into the bronchial tubes, the pleural cavity, or through the diaphragm into the abdominal cavity.

Cystic, Fibrous, Cartilaginous, and other forms of tumors, are occasionally found in the lungs, and, while they are generally small, they may acquire such size as to become a source of trouble during life.

The Bronchial Tubes.

The examination of the trachea and bronchial tubes in post-mortem examinations, is too frequently omitted. The lungs having been removed from the chest, they may be readily opened along their posterior aspect, and the bronchial tubes traced into the substance of the lungs. The pathological conditions of the bronchial tubes which may claim our attention, are inflammation in its various forms, obliteration, and dilatation.

=Bronchitis.= Bronchial inflammation has been divided into two varieties, according to the portion of the tubes affected. In one case the disease may be confined to the large and medium sized tubes; it is then known as tubular bronchitis. In the other, it is seated principally in the terminal ends, where the lining membrane is more delicate, and the tubes much smaller, and from this, extending to the air cells, forms what has been called vesicular bronchitis. The latter form is closely allied to pneumonia; in fact the two diseases pass into each other, and in most cases probably coexist.

Ordinary, or tubular bronchitis, is not often a fatal disease, hence we cannot speak accurately of its anatomical characters; yet, being frequently associated with other forms of fatal disease, we have opportunities of examining it under those circumstances. The lining membrane is then found thickened, rough, of a dark red or brown color, with more or less contraction of the calibre of the tube, and covered with a viscid, jelly-like mucus, often streaked with blood, and in some cases of a puriform character. This form of bronchitis may occur as a primary disease, or it may accompany tubercular consumption; is frequent in cases of heart disease, and may arise in the course of typhoid fever, measles, scarlet fever, and small-pox.

Vesicular bronchitis, from its involving the smaller tubes and air cells, is much more frequently fatal than the tubular form of the disease, although in fatal cases the two forms will usually coexist. In a post-mortem examination of these cases, we find the bronchial membrane red and injected, pulpy and thickened. In a more advanced stage, the air cells and smaller tubes are filled with a viscid, puriform mucus, which prevents the air from reaching the vesicles during life, and the lungs from collapsing upon opening the chest after death. Minute ulcers are not uncommon upon the mucous membrane, the effect of these, being that of changing the character of the secretion from a transparent mucoid, to an opaque purulent form.

Bronchial inflammation, as has been stated in another place, may result in emphysema of the lungs. In these cases, a valvular-like obstruction is produced in some of the bronchial tubes, which, offering little impediment to the entrance of the air, interferes with its escape, and thus by producing increased pressure upon the air cells supplied by the obstructed tube, a gradual dilatation or rupture ensues, resulting in the former case in vesicular, and in the latter, in interlobular emphysema.

Disease of the heart may also result from chronic bronchial inflammation. Not only respiration, but the circulation may be so impeded as to exert a direct influence upon the heart. From the difficulty which the blood encounters in flowing through the branches of the pulmonary artery, the main trunk of that vessel becomes permanently dilated, while the right ventricle, from the increased force required to overcome the obstruction in the lungs, becomes gradually dilated, and at the same time, perhaps, hypertrophied. From the union of the two ventricles, the excessive action of the right may induce a similar action in the left, and thus in time result in that hypertrophy of both ventricles, which is sometimes found in persons who have suffered from chronic bronchitis.

=Narrowing or Obliteration of Bronchial Tubes.= In some cases, in carefully tracing the bronchial tubes, we may find either a remarkable narrowness of the vessel, or a complete closure of the same. In the former cases, there is a distinct thickening of the walls of the tube, by an effusion of lymph, or blood and lymph, into the submucous tissues; or, from induration of the lung tissue around the smaller bronchial tubes, from tubercular or other deposits, a similar narrowing may result from external pressure.

Complete closure may be found in any portion of the tubes, in the large trunks, arising from the main branches, as well as in the smaller branches. They may be detected by passing a blunt probe into the tubes. The branches will frequently be found continuing from the points of closure, as a fibrous cord. The most common seat of these closures is in the upper lobe of the lung, yet they have been found in the lower lobes.

The causes of obliteration of the bronchial tubes is not well understood, yet, they are more frequently observed in persons who have suffered repeated attacks of bronchitis, or of chronic pneumonia.

=Dilatation of the Bronchial Tubes.= This condition of the bronchial tubes is more frequent in its occurrence than obliteration. It takes place in two forms, either several tubes are uniformly dilated, like the fingers of a glove, or a single tube may form a cavity, by undergoing a sacular enlargement. Some mechanical obstruction, by interfering with the free passage of air through the tubes, will usually have caused the difficulty, as an enlarged bronchial gland, pressing one of the bronchi. Here the free exit of the respired atmosphere being prevented, an accumulation of air takes place behind the narrowed point. Any impediment to the entrance or exit of the air into the lungs will produce irregular and forcible breathing, and throw a greater strain upon those parts especially which are in the vicinity of the obstacle. If, at the same time, the patient suffers an attack of asthma, bronchial catarrh, or whooping-cough, the violence of the cough materially aids in developing the dilatation.

The degree of dilatation is greatly variable. Tubes which, in their natural state, are not larger than a crow-quill, may, especially in the lower and middle lobes, reach the size of the finger, while at various points, sacular dilatations may occur, which at first sight may appear as vomicæ, but which upon more careful inspection, prove to be dilated portions of the bronchial tubes. The tubes in this state are usually filled with a puriform fluid, upon the removal of which the lining membrane is seen to be reddened and softened, or perhaps ulcerated.

This condition of the bronchial tubes may frequently be detected during life. The voice is hoarse, like a person in croup. The cough is also hoarse and brazen, while the breathing is difficult, and mucus rattling is heard in the middle or lower portion of the lung.

The post-mortem appearances in cases of foreign bodies in the bronchial tubes, may be readily anticipated and easily recognized.

The Mediastinum.

Inflammation may arise in the anterior mediastinum, from fracture or caries of the sternum; and in the posterior, from injury, inflammation, caries, or necrosis of the vertebræ. This inflammation may also result in the formation of an

Abscess; or, ulceration and perforation of the œsophagus, or inflammation of the lymphatic glands may lead to the same results. These abscesses may reach large size, resulting in displacement of the heart, and may rupture into the pleural cavity, the trachea or œsophagus.

Tumors of various kinds, may also develop within this space, including the several forms of cancerous growths. The latter will frequently have their origin in the bronchial or lymphatic glands, or, perhaps, in the remnant of the thymus gland.