Incision and expression of the contents, and touching the base of the cavity with silver nitrate. Pedunculated growths may be ligated. In some cases an ointment of ammoniated mercury, twenty to forty grains to the ounce, applied, by gently rubbing, once or twice daily, will bring about a cure. #Callositas.# (_Synonyms:_ Tylosis; Tyloma; Callus; Callous; Callosity; Keratoma.) #What do you understand by callositas?# A hard, thickened, horny patch made up of the corneous layers of the epidermis. #Describe the clinical appearances.# Callosities are most common about the hands and feet, and consist of small or large patches of dry, grayish-yellow looking, hard, slight or excessive epidermic accumulations. They are somewhat elevated, especially at the central portion, and gradually merge into the healthy skin. The natural surface lines are in a great measure obliterated, the patches usually being smooth and horn-like. _Keratosis palmaris et plantaris_ (symmetric keratodermia), as regards the local condition, is a somewhat similar affection. It consists of hypertrophy of the corneous layer of the palm and soles, usually of a more or less horny and plate-like character, but is congenital or hereditary, and not necessarily dependent upon local friction or pressure. #Are there any inflammatory symptoms in callositas?# No; but exceptionally, from accidental injury, the subjacent corium becomes inflamed, suppurates, and the thickened mass is cast off. #State the causes of callositas.# Pressure and friction; for example, on the hands, from the use of various tools and implements, and on the feet from ill-fitting shoes. It is, indeed, often to be looked upon as an effort of nature to protect the more delicate corium. In exceptional instances it arises without apparent cause. #What is the pathology?# The epidermis alone is involved; it consists, in fact, of a hyperplasia of the horny layer. #State the prognosis of callositas.# If the causes are removed, the accumulation, as a rule, gradually disappears. The effect of treatment is always rapid and positive, but unless the etiological factors have ceased to act, the result is usually but temporary. #How is callositas treated?# When treatment is deemed advisable, it consists in softening the parts with hot-water soakings or poultices, and subsequently shaving or scraping off the callous mass. The same result may also be often effected by the continuous application, for several days or a week, of a 10 to 15 per cent. salicylated plaster, or the application of a salicylated collodion, same strength; it is followed up by hot-water soaking, the accumulation, as a rule, coming readily away. #Clavus.# (_Synonym:_ Corn.) #What is clavus?# Clavus, or corn, is a small, circumscribed, flattened, deep-seated, horny formation usually seated about the toes. #Describe the clinical appearances.#