When a patient presents the symptoms of a threatened abscess in the vicinity of the rectum, he should be directed to go to bed, or at least to avoid all undue exercise; the bowels should be thoroughly evacuated, preferably by the use of a saline cathartic; the diet should be nutritious; and, if the case be seen early, hot fomentations and poultices may be applied to the parts. The early adoption of these measures may abort the threatened abscess. If, however, there be reason to suspect that matter has formed or is forming, it will be advisable to make a free incision into the center of the affected site with a sharp curved bistoury, if the trouble is superficial, or, if it is deep, with a narrow straight knife. When pus is present and is deeply seated, the evacuation of the abscess will be aided by the introduction of the forefinger into the bowel, by which means the swelling may be pushed forward, rendered tense, and hence made more apparent. In opening these abscesses, if possible, ether should be given. The patient should lie on the side on which the threatened abscess is situated; the upper leg should be bent forward upon the abdomen. When pus is present, the operator should stand out of the line of its exit, for when the cavity is opened it often squirts out a considerable distance. After the matter has been discharged, the forefinger should be introduced into the abscess-cavity for the purpose of breaking down any secondary cavities or loculi that may exist. When this has been accomplished, the abscess should be thoroughly washed out with peroxide of hydrogen (Marchand's, undiluted, or some other reliable preparation), after which a rubber drainage-tube should be inserted, or a piece of iodoform gauze should be lightly placed between the lips of the incision, to prevent its closing too rapidly, and also to allow free drainage. Careful daily attention should be paid to the wound while the cavity of the abscess is contracting, as it is important to maintain a free and dependent outlet for the matter which continues to be secreted; but stuffing and distention of the cavity should be avoided. If a drainage-tube be used, it should be shortened from day to day as the wall of the abscess contracts. After an operation for rectal abscess, the patient should be kept quiet for several days; and if great care be taken, both with the subsequent drainage and in keeping the orifice open, the part may heal without the formation of a fistula. TREATMENT OF FISTULA IN ANO.—The treatment of fistula, like that of fissure, may be either _palliative_ or _operative_.