2. Suhmueous tissue, which is the seat of oedematous effusions, and of the sloughy and pu trid matter produced by diffuse inflammation.
3. Cartilage, in which we remark great and important varieties of disease, such as inflam mation, ulceration, mortification, degeneration into an earthy unorganized material, atrophy, hypertrophy, and some alterations of shape and structure probably depending on scrofula or other constitutional taint.
4. Muscle, the seat of those spasmodic ac tions so frequent and so perilous in laryngeal affections, and perhaps occasionally of gout and rheumatism also.
5. Ligaments. I know not whether disease ever originates in these structures, but there can be no doubt that they are sometimes removed by ulceration, and there is reason to believe that great inconvenience and even danger may be occasioned by a preternatural relaxation of some of them.
1. Acute inflammation of the mucous mem brane is always in the first instance attended by a change of colour more or less intense ac cording to its situation, being comparatively pale where it is closely attached to a subjacent cartilage, but of a deep and concentrated red tint, verging on purple, where it is more loosely connected by the intervention of cellular tissue or muscle. The membrane is also swollen, soft and pulpy, these characters being likewise influenced by thednature of its connection to subjacent parts, and I believe the usual symptom of inflammation, " pain," is not ab sent, although the mental agony attendant on obstructed respiration renders this a secondary consideration to the patient : certainly in the laryngitis of the adult, pressure on the pomurn Adami is very sensibly felt. In connexion with these changes the functions of the organ are interrupted and impaired. The usual secretion of the membrane is diminished in quantity, or perhaps ceases altogether, and hence the sen sation of dryness or huskiness in the throat, and the peculiar solitary ringing cough that uniformly is present. The voice is also in jured, being occasionally nearly if not altoge ther lost, and there is difficulty of breathing accompanied by a harsh stridulous sound ; this latter being caused by the mechanical obstruc tion to the passage of air produced either by tumefaction or by spasm. Having continued a given time,—and the first stage of inflammation of the larynx if very acute is usually but short,— certain results or effects are developed, which, differing in the child and the adult, require a brief separate notice for each.
The acute laryngitis of the child, or croup, although generally commencing in the larynx alone, and sometimes altogether confined to it, is by no means uniformly so : on the contrary, it not only may commence in or extend to the trachea, but possibly have its origin in the bronchial cells, and pass thence upwards along the tubes. It may also perhaps not be strictly correct to arrange croup amongst the diseases that are preceded or accompanied by inflam matory fever, for occasionally it makes its at tack without any previous warning whatever, and a child that had retired in apparently per fect health may arouse and alarm its attendants in the middle of the night with the sounds of that dry, harsh, and incessant cough, and that loud and stridulous respiration which afford to the practised ear the painful but unerring evi dence of the nature of the mischief present.
In either case, however, the disease hastens to its second pathological state, in which the evi dences of increased vascularity begin to disap pear, and are succeeded by the secretion or effusion of a viscid tenacious lymph, which, assuming the form of a membrane, has ob tained the name of the false or adventitious membrane of croup. This substance is of a pale yellow colour, viscid and tenacious ; more generally found in the larynx than the trachea ; seldom occupying the entire circumference of the tube ; unorganized ; incapable of becoming the medium of union between opposing sur faces, and with a strong disposition to separate from the surface on which it was originally formed. It usually commences in the larynx, and travels downwards along the trachea; more rarely it seems to begin in the ramifications of the bronchial cells; and again, still more sel dom is the entire of the mucous membrane attacked at once, and the adventitious mem brane thrown out over its whole extent. Con sidered as a pathological production, this false membrane or croup presents some curious and interesting subjects for observation, for although so generally met with that by some it has been regarded as the essential characteristic of the disease, yet perhaps it is not invariably or ne cessarily so ; at least I have seen cases so far resembling croup in all their stages, that they could not be distinguished from it during life, in which dissection subsequently sheaved the mucous membrane swollen, and soft, and pulpy, with copious submucous effusion, yet without the formation of a single flake of lymph. Possibly in the few cases of this de scription that came under my observation, the disease had proceeded with a rapidity which proved fatal before the membrane had time to have been formed. Again, it is the only instance of lymph being produced on a mucous surface as the result of active acute inflamma tion. In chronic affections membranous layers of lymph are often formed, and in different situations, as in the bronchial cells and the mucous coat of the intestines, but the acute produces it alone in the structures that are the seat of croup. And lastly, it appears that this effect of inflammation is restricted to patients under twelve years of age. Mr. Ryland, in his excellent treatise on the larynx, has published a table from Bricheteau, by which it is shewn from the experience of fourteen distinguished authors, that croup " has never occurred at a later age than twelve years, and very rarely at that age." My friend, Dr. W. Stokes, con siders the cases published as examples of croup occurring in the adult as not being inflamma tory croup at all, but analogous to the diphthe rite of Bretonneau, which will be shewn to be a very different disease indeed.