The typhous process occurring in the air-passages presents numerous peculiarities in reference to its connection with the general disease, with the morbid state of the mucous membrane of the small intestine, where amongst us it usually becomes localized as ileo-typhus, and in reference to its seat generally.

In all cases of typhus it invariably occurs as a typhous bronchial catarrh, with tough and gelatinous-looking mucous. The catarrh seems to be developed in proportion to the intensity of the general disease, and is most severe in those cases which are marked by the predominance of catarrho-pectoral symptoms. It may occur here as the true, special typhous process, either in its genuine or its degenerate form; in this former case it may be either primary or secondary; in the latter case it is always secondary. Its seat is sometimes on the bronchial and at other times on the laryngeal mucous membrane; on the former it frequently occurs as primary broncho-typhus, and is a very serious affection; on the latter, constituting laryngo-typhus, it is almost always, at at least amongst us, a secondary process.

A. Genuine typhus on the bronchial mucous membrane always appears as an intense, diffused congestion; the mucous membrane is of a dark, almost violet tint, is swollen and succulent, and yields a secretion of a gelatinous and sometimes dark, blood-streak mucus, occurring in large masses. The disease is most commonly developed in the bronchial ramifications of the lower lobes; it is always limited to the stage of typhous congestion, and never gives rise to any apparent production of a secondary formation on the tissue of this membrane, such as is produced in immense quantity in the intestinal follicles in cases of abdominal typhus.

In primary broncho-typhus the general disease originally localizes itself here, avoiding all other mucous membranes, even that of the intestine, for which the typhous process in general shows the most decided preference; the latter mucous membrane exhibits, however, in many cases a recognizable, although always subordinate and secondary development of the follicles, in which the adjacent mesenteric glands participate; and in such cases it is very often a difficult matter to distinguish the typhus in the above-named affection of the bronchial mucous membrane. The peculiar stasis of the spleen and of the great cul de sac of the stomach, the remarkable intumescence of the former, and the singular character of the blood, the typhous nature of the general disease, and especially the altered condition of the bronchial glands, invariably serve, together with other symptoms, to indicate the typhous nature of the bronchial affection. The alteration occurring in the bronchial glands is of the same character as that affecting the mesenteric glands in abdominal typhus; they become swollen to the size of a pigeon's or even a hen's egg, are of a dark, violet color which afterwards becomes lighter, present a relaxed and friable appearance, and are infiltrated with medullary typhous matter. Like typhous mesenteric glands they may become the seat of tumultuous metamorphosis, and thus, either with or without perforation of the adjacent mediastinum, may give rise to pleurisy.

This form is often combined with pneumo-typhus and typhous pleurisy, and is beyond all doubt the basis of the spotted contagious typhus, and very probably, also, of the Irish and North American typhus, which, in the majority of cases, run their course without any intestinal affection. With us this affection is rare, and, in point of frequency, is not to be compared to abdominal typhus.

Genuine secondary bronchial typhus presents the same anatomical characters, in a less highly developed state, as the primary. In a degenerate form it is very rare, occurring, for the most part, as bronchial croup, or as diffuse gangrene of the bronchial mucous membrane.

b. Laryngo-typhus is with us an unusually common and extremely unfavorable symptom in many epidemics in typhus. It scarcely ever occurs as a primary independent affection, but is almost invariably secondary, and forms, as it were, the completion of intestinal typhus, on various anomalies of which it is generally based.

It is almost invariably situated on the laryngeal mucous membrane above the transverse muscle, and towards the posterior extremities of the ventricles (a situation which, as we shall presently see, appears favorable to all the pseudo-plastic processes); it may, however, occur on the mucous membrane of the epiglottis, especially towards its lateral borders; and sometimes it occurs simultaneously at both these spots.

It, no doubt, frequently occurs in the genuine form, but it is only rarely that we have the opportunity of observing the typhous infiltration in its stage of crudity or of metamorphosis; as we see it in the dead body, there is almost invariably a loss of tissue, or ulcers of the same kind as those of the intestine, but less deep-seated.

Laryngo-typhus occurs, however, far more frequently in a degenerate form, either as an exudative process (croup), or more commonly as gangrene. The latter, after its detachment, leaves an ulcer, which cannot be distinguished from the degenerate typhous ulcer, so that we are unable from these appearances to draw any certain inference regarding the original process.

These ulcers are of a roundish shape, varying from the size of a lentil to that of a pea: they are either discrete or confluent, two or three often forming a group. They are seated at the spots we have already mentioned, on the posterior wall of the larynx and on the lateral edges of the epiglottis, on both of which situations they occur as linear ulcers; when, as is sometimes the case, they present themselves on the inferior surface of the epiglottis, they present a roundish or lenticular form; they are lax, discolored, and are black at the edges from the deposition of pigment; they gradually eat their way into the transverse muscle, the arytenoid and cricoid cartilages, the vocal chords and epiglottis, in which they give rise to softening, necrosis, and exfoliation. On the posterior laryngeal wall abscesses are not unfrequently developed, in which the necrosed arytenoid cartilages lie bathed in a brownish ichor; these abscesses sometimes penetrate into the pharynx. The whole constitutes a typhous laryngeal phthisis.

Laryngo-typhus is very frequently combined with pneumonia, and with secondary broncho- and pharyngo-typhus.