the mucous surface of the digestive tube; particularly of the oesophagus, stomach, and large bowels. In all these consecutive and complicated states, it presents no certain or unvarying forms; its chief character, its duration, progress, and termination, being modified by its severity, by the constitutional powers of the patient, by his diathesis, by the nature of the complication, and by the quantity of expectoration. In some protracted cases, the secretion from the bronchial surface is so profuse as to be the chief cause of the exhaustion and death of the patient.

CHAPTER III.

THE DIAGNOSIS AND PROGNOSIS OF BRONCHITIS.

i. OF THE DIAGNOSIS OF BRONCHITIS.

THE characters of the cough, and of the sputa, the physical signs, and the constitutional symptoms, are our chief guides in the diagnosis of bronchitis. The history I have given of the disease will be generally sufficient to enable even the inexperienced to recognise it; but it will often be necessary to arrive at more precise information as to the extent of lesion, and its existence either in a simple or in a complicated form.

38. A. Of acute Bronchitis.-a. By auscultation. In the first stage of the disease, the inflammation causes tumefaction of the mucous bronchial surface, and consequent diminution of the calibre of the tubes. This state occasions a modification of the respiratory sound in them; and hence, either with the unaided ear, or with the stethoscope, we hear at first the dry bronchial rhonchus;' consisting chiefly of a sibilous or whistling sound; occasionally with a deeper tone, resembling the note of a violoncello, or the cooing of a pigeon, particularly when the large bronchi

are affected. These sounds, denominated the sibilous and the sonorous rhonchi, are present chiefly in the early stage, and before expectoration takes place; and prove the accuracy of the rational inference of Dr. BADHAM, that the difficult breathing of this period is owing to the state of the mucous membrane; and, I would add, of its submucous cellular tissue also. To these sounds is added the mucous rhonchus; and in proportion as the bronchial secretion, to which it is owing, .augments, this sound becomes predominant. When the inflammation is seated in the large tubes, the bubbles of mucous rhonchus are large and uneven; and the respiration may be still heard over the chest. But when the mucous rhonchus is fine, and is heard constantly, it may be inferred that the small bronchi are invaded. When this is the case in a severe degree, there is also slightly diminished resonance of the chiefly affected part upon percussion. As the disease proceeds, and the secretion passes into an opaque and thickened state, the mucous rhonchus becomes interrupted, sometimes with obstruction of the respiratory sound in a portion of the lungs, and passes into a sibilant or clicking sound. These changes arise from the entire or partial obstruction of one or more tubes by the thickened mucus, and are generally of temporary continuance; occurring now in one part of the chest, and disappearing; and now in another. This state of the bronchi fully explains the dyspnoea of this stage.

39. b. Rational Diagnosis.-a. The cough in bronchitis is loose, diffused, and deep; in paroxysms, and attended with fever, often with wheezing. In pertussis, it is in severe paroxysm, unattended by fever or wheezing; is accompanied with a distinct whoop; and terminates in vomiting. In croup it is sonorous, clanging, and harsh. In laryngitis, it is suffocating, shrill, or grunting; and, on inspiration, attended with a drawing down of the pomum Adami to the sternum, and retraction of the epigastrium and hypochondria. In pneumonia, it is deep in the chest; frequent and short, often hard; and gives a metallic sort of noise. And, in pleuritis, it is short, dry, hard; sometimes slight, but always suppressed and painful. --B. The expectoration in bronchitis is abundant after the second or third day, or even from the first; in pertussis, it only follows the vomiting: in pneumonia, it is more rounded, distinct, thickened, purulent, rusty, and intimately streaked with blood: in pleuritis, croup, and laryngitis, it is scanty, thin, frothy in the latter; sometimes with shreds or pieces of lymph, and entirely different in appearance from that of bronchitis.-y. Pain in bronchitis is scarcely complained of; and consists merely of a sense of soreness, heat, and tightness in the chest, particularly beneath the sternum, and is not increased on full inspiration: in pneumonia, it is more marked, especially in certain parts of the chest, generally nearer the lateral regions, and is increased on inspiration or pro

longed expiration: in pleuritis, it is very acute, and a full inspiration is impossible: in croup and laryngitis the pain is increased upon pressing the trachea and larynx.-8. The countenance in bronchitis is more frequently pallid or bloated: in pneumonia, it is generally flushed; and dyspnoea is greater in the former than in the latter. The breathing is wheezing and hurried in acute bronchitis; in pneumonia it is less so, and generally without the bronchial wheeze. The pulse, in the former, is frequent, full, free, developed, and soft; in the latter full, hard, bounding, or vibrating, and sometimes oppressed and undeveloped. The general febrile symptoms are more continued in pneumonia than in bronchitis; morning remissions, with free perspiration, being more frequent in the latter than in the former. The physical signs in pneumonia, pleuritis, &c., are the surest means of their diagnosis.

40. C. Some cases of asthenic bronchitis may be mistaken for humoral asthma; and occasionally no very distinct line of demarcation can be drawn, both affections either insensibly passing into each other, or being complicated with one another. But, generally, the slow accession of the former, the more continued and less urgent dyspnoea and tightness of the chest, and the presence of febrile symptoms, particularly great quickness of pulse, will distinguish it from humoral asthma; which is commonly characterised by the sudden accession of the paroxysms, their severity