A. In several of the exanthematous processes the sudoriparous glands and their ducts are unquestionably subject to frequent and various diseases, both primary and secondary, but the anatomical investigation of their diseases is attended with many difficulties, and no advance has yet been made in it. Our knowledge is limited to the anomalies in the quantity and physical properties, most of them, therefore, symptomatic anomalies, of their secretion, i. e. of the perspiration: but chemistry has hitherto supplied information in some striking cases only, and the investigation is beset with as many hindrances as before.

B. The sebaceous follicles and their excretory ducts are certainly the true and the original seat of many exanthematous processes; but their most frequent morbid condition is enlargement, arising from the accumulation of thickened secretion within them. The least degree of the affection, and a very common one, is dilatation of the duct of the gland, and is known by the name of Mitesser, - maggots [Comedones). The accumulation of the secretion in the sudoriparous sac itself produces white rounded tumors,of the size of gravel, or millet-seed. When dilated to a greater, the sac degenerates, either alone or together with its excretory duct, into a cyst as large as a pea or a hazel-nut, or even larger; when it is diseased alone it is opened externally; but in the latter case it separates from its duct, and completely closes: it contains a whitish, laminated, firm substance, like adipocire, or a pulpy substance, viscid like fat, and consisting of strata of epidermis, and crystallized fat. In all these forms the disease occurs principally in the larger sebaceous follicles on the face, at the upper part of the trunk, on the back, and in the neighborhood of the parts of generation.

The diseased sebaceous glands frequently give rise to inflammation of the adjoining corium - to acne, - an inflammation that sometimes goes on to suppuration of the follicle, as well as frequently of the bulb of the hair with which it is connected, and sometimes to induration (acne indurata), and thereby to a slow cure.

In large sebaceous cysts the epidermal mass sometimes takes the form of a horny excrescence, - a growth to which I shall advert presently. In other cases their contents become inspissated, and form calcareous concretions.

The occurrence of a condyloma in the sac of one of these glands - condyloma subcutaneum of Hank - is a very interesting phenomenon, which for that reason requires further investigation.

The secretion of the gland is sometimes more abundant than natural, and is poured out upon the surface of the skin (seborrhagia): it dries there in thin whitish, glistening laminae, or in thicker, dirty strata or scabs, which feel like fat.