I. (a) The seat of pneumonia, though mainly interesting anatomically, is not devoid of clinical import, as a guide to the observer in quest of the physical signs of the disease. Of one thousand four hundred and thirty cases, seven hundred and forty-two were of the right lung, four hundred and twenty-six of the left, and two hundred and sixty-two of both organs. In two hundred and sixty-four cases, the upper lobe was affected one hundred and one, the lower one hundred and thirty-three, the middle part thirty, times (Grisolle.) With respect to the cases of double pneumonia, which hold a rather high numerical rank (they furnish 18.3 per 100 of the whole series,) it is to be observed that the great majority of them were not so from the outset; in other words, that the implication of the second lung was secondary in point of time. This, indeed, is a matter of no mean importance; for in doubtful cases the existence of the phenomenon at one only or at both sides of the chest, will aid materially in distinguishing the true crepitant rhonchus of pneumonia from the subcrepitant of capillary bronchitis. And even with the qualification now mentioned, alone, the frequency of double pneumonia is probably considerably exaggerated in the estimate just given: subcrepitation has often been mistaken for true crepitation, and a double capillary bronchitis put down as a double pneumonia; it is traditionally well known in Paris that even Laennec committed this error. The age of patients, too, must be borne in mind: in the adult, the proportion of double pneumonias does not probably much exceed one in twelve; it has even been estimated so low as one in seventeen. On the other hand, the disease is almost always double in newborn infants; in one hundred and twenty-eight such cases, observed by MM. Valleix and Vernois, the right lung alone suffered in seventeen cases, the left alone in no single instance; while both lungs were affected one hundred and seventeen times. Pneumonia commencing about the middle of the lung is rarely primary: it is commonly either a sequence of endo-pericarditis or of blood origin,—an anatomical fact of obvious practical signification. The anterior margin of one or both lungs is sometimes separately inflamed: I believe that the frequency of this peculiar seat has been exaggerated from confounding mediastinal pseudo-crepitation with true pneumonic rhonchus.

In the scholar year 1834-5, when I was attending at the Hôtel-Dieu, 48 cases of pneumonia occurred in the wards of M. Chomel: 33 of these were of the right lung; 11 of the left; 4 were double.

(b) The pneumonia of infancy very frequently (but by no means so constantly as is usually taught,) instead of spreading through a lobe of the lung generally, limits itself to scattered groups of lobules, the intervening tissue remaining sound: such pneumonia is called lobular.* So, too, pneumonia preceding the formation of secondary abscesses in the lungs, sequential to phlebitis, &c., commonly assumes this form, no matter what be the age of the individual.

The physical signs of lobular pneumonia are obscure. Inspection, application of the hand, and mensuration give merely negative results. Percussion, too, does not disclose such an amount of dulness as can be clinically trusted to; which is no more than might be anticipated, when we consider that the nodules of consolidated lung are separated by tissue perfectly permeable. In many cases originally (to all appearance) lobular, I have found the sound duller than natural, it is true; but when this was the case, and the opportunity of examining the parts occurred, I invariably discovered such extension of the inflammation between the nodules as to reduce the organ, physically speaking, almost to the state of ordinary consolidation. The respiration is exaggerated in some points; harsh, bronchial, or even slightly blowing (never tubular, so long as the pneumonia is simply lobular,) in the spots probably corresponding to the consolidated nodules. Occasionally a few cracklings of an imperfect crepitant rhonchus may be heard; but it is difficult to distinguish these from the humid rhonchus of fine bronchitis, -a disease almost constantly associated in children with inflammation of the parenchyma.†

(c) The interlobular cellular tissue may be the seat of acute suppurative inflammation, pus occupying the situation that is filled by air in interlobular emphysema. Or this tissue may be

True lobular pneumonia is distinguished in the dead subject from collapse, and consequent solidity, of lobules, by its being insusceptible of inflation; while merely collapsed nodules of tissue, as originally shown by Bailly and Legendre, may be blown up to their natural, or very nearly their natural, state. It is impossible to say in how many of the series of infantile pneumonias, above referred to, the real condition was nothing more than the collapse in question.

†The signs of diffuse pneumonia in the infant scarcely differ from those noticed in the adult. Crepitation, metallic tubular breathing, and dulness, under percussion are the essential signs: the child's cry resounds with sniffling bronchophonic character. The crepitation is of larger size than in the adult.

Carswell's framed drawings, U. C. Museum, No. 57, C. b. 573.

infiltrated with fibrinous exudation, which solidifies into induration-matter, and causes considerable contraction of the lung, and sinking in of the side (Corrigan's "cirrhosis.") The bronchi undergo marked dilatation; and the pulmonary tissue, compressed by these tubes and by the surrounding indurationmatter, acting with its peculiar steady and constant force, becomes almost completely impermeable.*

The physical signs are flattening and diminished width of the side, impaired costal motion, increased vocal fremitus, percussion hard and dull or tubular, respiration irregular in distribution, weak, deep-seated, bronchial, or diffused blowing; while the rhonchi of bronchitis with hollow respiration indicate the existence of dilated tubes. The heart may, by this condition of things, be drawn to the affected side: as, however, there is very generally co-existent agglutination of the two laminæ of the pleura, it is difficult to say to what extent the state of the lung alone contributes to the displacement of the heart; such was the fact in the case of S. Osmond, referred to in the note at the foot of this page.

The distinction during life of this state of the lung from simple chronic pneumonia is always difficult, sometimes impossible. In "cirrhosis" of the organ, retraction of the side is, however, greatly more marked than in ordinary chronic inflammation; and if there be a considerable amount of flattening, we may be certain that it is not caused by the latter disease alone. The tubular percussion-sound, stronger respiration, signs of dilated bronchi and traction of the heart towards the affected side (only distinguishable on the right,) met with in cirrhosis, are not observed in the simple disease.

II. (a) Instead of running its ordinary course with marked subjective symptoms, pneumonia may be completely latent. The perverted ratio of the pulse and respiration, and the physical signs, are then the sole guides to the detection of the disease. Pneumonia occurs in this form solely under circumstances of general physical debility: it is either senile or connected with adynamic diseases, of which it is an intercurrent pheno

menon.

Physically, latent pneumonia is characterized by the rapidity with which it runs into solidification, and with which it involves a great extent of substance.

* In a remarkable case of the kind (S. Osmond, U. C. H., Males, vol. iv. p. 336,) I found an infiltrated cellulo-fibrous tissue actually replacing certain lobules of lung: the pulmonary texture had been absorbed.

In managing this form of inflammation, the main attention must be given to the state of the system generally. Venesection I cannot believe to be ever requisite; and abstraction of blood, even locally by cupping, should be very cautiously ventured on. Still, if the respiration be much accelerated, and consolidation very rapidly extending, a few ounces of blood may be taken by cupping. Dry-cupping is always a measure of utility, and unattended with danger. The early application of blisters is by some observers strongly recommended in this variety of the disease: I have not happened to observe results justifying their confidence. Sesqui-carbonate of ammonia, bark and wine-the remedies for the existing state of the system at large-exercise, in my opinion, the most obvious and immediate good effects on the local disease.

(b) Under the phrase "hypostatic pneumonia" have been described mere passive congestion of the bases of the lungs, occurring shortly before death, and also the senile and adynamic inflammations just referred to.

Where the tendency to such congestion exhibits itself, occasional change of posture from the back to the sides, or even to the prone position, is one of the most important remedies; and, indeed, this is true, more or less, of every variety of pneumonia.

III. It is impossible to exaggerate the importance of pneumonia in its next variety,-namely, when occurring as a secondary or intercurrent disease: in truth, the majority of cases of pneumonia belong to this class. It is intercurrent pneumonia that commonly kills new-born infants, affected with hardening of the cellular tissue and diphtheritic disease. From childhood to puberty, croup, cancrum oris, measles, hooping-cough, variola, frequently prove fatal (especially croup,) through inflammation of the lungs. Again, we meet it complicating the diseases of the adult,—and if not at this period so frequently fatal, not the less important for the practitioner to watch. Thus it appears in typhoid fever, phlebitis, glanders, puerperal fever, inflammation of the bowels, and of the brain or membrane, and in acute rheumatism; among chronic diseases, in pulmonary tubercle, Bright's disease, chronic affections of the liver, not so commonly as might be expected in organic diseases of the heart, in cancerous affections, not only of the thoracic, but of distant organs, &c. In treating intercurrent pneumonia, we must remember that the inflammatory character of the local malady is modified more or less seriously by the general state of the system. It is ex

ceedingly probable, indeed, that various differences exist in the intimate constitution of many of the intercurrent pneumonias,though at present no absolute proof of the fact can be given. Hence, if antiphlogistic management be proper, as it positively is in these cases, the state of the system at large should always be allowed full control. This is more especially true in the instance of diethetic diseases, such as rheumatism: it may be that colchicum is a more important remedy than antimony for rheumatic pneumonia. In pneumonia complicating purpura, the treatment (except in regard of blistering and dry-cupping) is wholly that of the blood-disease present.

GANGRENE OF THE LUNG.

I. Gangrene of the lung occurs in two anatomical forms,the diffused and the circumscribed;-the latter, greatly more frequent than the former, is distinguished by the sharp line of demarkation between the gangrenous and sound tissue.

II. (a) The symptoms in the diffused form are great general prostration, suppressed breathing, profuse expectoration, frothy and purulent-looking, of gangrenous odour, with a small, feeble, and very frequent pulse, and all the general appearances of intense adynamia. The power to expectorate is soon lost, and death occurs from suffocation.

(b) The course of circumscribed gangrene is somewhat different. At first the evidences of affection of the lung are commonly extremely obscure; the signs of pulmonary congestion exist, coupled with an amount of prostration quite out of proportion with the extent of local disease; the expectoration muco-purulent, rarely bloody in adults, frequently so in infants and children, acquires, the moment communication is established between the bronchial tubes and the gangrenous tissue, properties more or less strongly characteristic of the disease. It is of dirty-greenish, yellowish brown, or ash-gray colour; very liquid; and exhales an odour distinctly gangrenous, or resembling that of wet plaster, or sui generis but painfully fetid. In the adult the breath generally has the same fœtor, but this may not be constant: the expired air may be completely free for some minutes at a time from disagreeable smell; when suddenly, without cough or any other apparent cause, it becomes intolerably fetid. Possibly temporary plugging of the bronchi communicating with the mortified tissue may account