The Mucous Membrane Of The Stomach almost invariably suffers the changes of the third degree, though in varying extent and thickness. It is either affected in single folds, or streaks which pass from the cardiac orifice to the lesser curvature, and from the large curvature to the pylorus; or over a large extent; or we find the entire surface converted into a black carbonaceous mass, of several lines in thickness, distended by sanguinolent fluid, and consequently presenting a tumefied appearance. The muscular coat is altered in the manner peculiar to the third degree, and we therefore often find the parietes of the stomach perforated.

The acid affects the neighboring organs through the membranes, and thus either coagulates or tans the contained fluids, fuses the tissues into a gelatinous mass, or carbonifies them; the discoloration produced is always very marked. In many cases, not only the blood of the neighboring bloodvessels, but also of the larger trunks, and even of the aorta, is changed into pultaceous, pitchy, greasy, black cylinders. Beyond the stomach, and especially in the duodenum, and at the commencement of the jejunum, the effect of the lowest degree is exhibited in coagulation of the intestinal mucus, and of the chyle, in corrugation and opacity of the epithelium, in the tanned state of the mucous membrane, and the dark injection of its vessels. The consequences and results are modified according to the intensity of the operating influence.

The highest degrees, in which, generally, a very extensive surface is involved, produce a rapidly fatal termination. The lowest degrees are followed by exudative inflammation; the mortified epithelium sloughs, and being replaced by a new formation as soon as the reaction has abated, recovery ensues.

In all the higher degrees we have reactive inflammation in the healthy tissue, which effects the rejection of the superincumbent mortified tissue by passing into suppuration. As the inflammatory and suppurating processes diminish, the tissues contract, cicatrices form, and a cure results; or suppuration is protracted, causing a late recovery, or ending fatally in oesophageal phthisis.

According to the depth to which the tissues are destroyed, the loss of substance is repaired under a formation of strictures, that vary in size and consistency.

If the mortification be limited by the submucous cellular tissue, we shall find the latter condensed over the pale, ashy, muscular coat, which now resembles the elastic tissue, into a serous, or fibro-serous, tissue, replacing the mucous membrane to a considerable extent. This tissue forms, at some places, projecting ridges, or valvular, and even annular, duplications towards the oesophagus; and we thus have a peculiar membranous stricture of the latter produced, not unlike the strictures found in dysentery.

If the muscular coat itself is involved, it is partially or entirely destroyed, and the walls of the oesophagus are converted into a fibro-cellular firm tissue, which contracts, and thus produces the most important and most resisting strictures.

These strictures are formed chiefly, though not exclusively, at the lower section of the pharynx, posterior to the cricoid cartilage, and in the vicinity of the cardiac portion. We also not unfrequently see, besides these strictures, solitary insulated remains of the mucous membrane on the inner surface of the oesophagus, in consequence of the contraction of the new tissues. They have a shrivelled appearance, and are in part detached, or form transverse bands.