This is the common inflammation of mucous membrane; it is sometimes an ordinary catarrh, resulting from the known atmospheric influences; sometimes it is the local expression of a constitutional disease, and is then a specific catarrh, either exanthematous, typhous, impetiginous, gouty, or the like: occasionally it is produced by direct mechanical or chemical irritants, etc.; moreover, it accompanies the various processes of ulceration and new growth that take place upon mucous membranes, varying in such cases both in intensity and in extent. Its course is sometimes acute, sometimes chronic.

A. Acute Catarrhal Inflammation

The anatomical characters of this disease are as follows:

(1.) Redness, which varies from a pale rosy tint to a deep red: it gradually diminishes towards the margin of the inflamed spot, and then passes into the natural color of the tissue.

(2.) The injection may involve merely the finer ramifications, or it may amount to a complete distension of all the vascular apparatus, and will, therefore, vary in each membrane according to the special arrangemerit of its peripheral vessels. To the unassisted eye, the membrane then appears uniformly saturated with red.

(3.) Even with a slight amount of reddening and injection, the inflamed membrane loses its transparency, and becomes cloudy.

(4.) Its tissue becomes filled with an opaque, grayish, or a sanguineous grayish-red fluid, and the membrane appears swollen: the papillae and mucous glands being in the same condition, its surface seems warty or papillary, and uneven. Sometimes the epithelium is raised in delicate, translucid, miliary vesicles, which are filled with a serous fluid.

(5.) It may be easily torn, and readily separated from the structures beneath. These structures, and especially submucous layers of cellular tissue, are loose, filled with a serous or sanguineo-serous fluid, spotted here and there with small extravasations of blood, and fragile.

(6.) At the commencement of the inflammation, the secretion exceeds the natural quantity, and is watery: as the inflammation advances it diminishes in amount, and becomes opaque and viscid: at the acme of the inflammation, it ceases altogether. After this it is gradually restored again, and is frequently streaked with a little blood: it then assumes a purulent appearance, and becomes very abundant: and remains in this condition for some time after all other marks of the inflammation, even the swelling of the tissue, have subsided. This is especially the case in mucous cavities.

Moreover, inflammations of very great intensity deposit a more or less plastic exudation upon the free surface of the membrane: the miliary vesicles upon catarrhal mucous membranes which were mentioned above, arise from this cause.

Acute inflammation often has a marked tendency to return upon slight occasions; severe attacks of it frequently terminate in superficial suppuration, which may even continue habitually. Not uncommonly it becomes chronic.