Aphthous Exudation, a yellow, greenish-yellow, dingy-grayish, opaque product, wont, upon surfaces, to solidify into tough membranes, and then melt down, reducing the implicated textures to the same condition. This said product consists sometimes in simple destruction of the textures, sometimes in a blending into a variously discolored, fetid, ichorous pulp, or into a tenacious, greasy slough, which tears like tinder.

These exudates affect, with especial frequency, the mucous membranes, particularly those of the alimentary canal, of the urine bladder, of the female sexual organs, with their follicles; secondly, external sores and ulcers; thirdly, the common integuments. Under this head belong thrush or aphthae, diphtheritis, exudates upon the intestinal mucous membrane of the intestines, and of the colon in particular as representing one form of dysentery, and of the uterus after childbirth; corroding exudates upon external and internal wounded and ulcerated surfaces, for example, on the base of the typhous ulcer, white gangrene of the common integuments, hospital gangrene.

Croupous exudation is occasionally the product of an intense inflammatory stasis, unconnected with any pre-existent crasis. It is, however, much more frequently the product of a stasis in which the croupous crasis has suddenly become localized.

(c.) A special form of fibrinous exudation is the tuberculous - the true fibrino-tuberculous. It is a repetition both of simple, and, when engendered by inflammation, of croupous exudation. It is characterized by a proneness to tarry long in its primitive, crude state, and eventually to soften down.

It exudes almost, if not wholly, pure, or else blended with a certain proportion of organizable fibrin. In the former case it represents a homogeneous gray, or yellow, curd-like, brittle, fissured mass; upon serous membranes, a similar uniform layer, of uneven stellate surface. In the second case, the tuberculous matter is imbedded in the shape of more or less crowded tubera clusters, or larger masses, within the other portion of the effusion, which has attained to various grades of textural development. In the last-mentioned case, more especially, tuberculous exudation is, upon serous membranes, always characterized by clustering of the granules. Tuberculo-croupous exudation affects serous and mucous membranes, evincing a preference for those of the bronchial, of the alimentary, canal, of the uterus, and of the cavity of the tympanum. It invades the parenchyma of organs at all points, but most of all that of the lungs, as infiltrated tuberculous pneumonia of the lobar, or still more commonly the lobular form, the substance of lymphatic glands; lastly, the interior of follicles, and particularly the Peyerian capsules.

There are cases in which it may be but the local produce of a stasis. More commonly, however, this stasis is itself a localization of the tubercle crasis, and the tuberculous exudate the prodcct of general dyscrasial processes.