SYMPTOMS.—The symptoms of fistula are not easily overlooked. Occasionally there is considerable pain present, but more frequently only a feeling of uneasiness about the anus is experienced. When a fistula originates, as I believe it most commonly does, from a preëxisting abscess, there is a sensation of weight about the anus, with swelling of the integument, considerable tenderness upon pressure, pain in defecation, and a constitutional disturbance associated with rigors. These symptoms are relieved after the matter is discharged. The exploring needle (Fig. 20) is often useful in determining the presence of pus in such abscesses in which it is impossible to obtain fluctuation. In complete fistula in ano, and in the incomplete internal variety, the evacuations are streaked or covered with pus and mucus, perhaps also slightly tinged with blood. [Illustration: Fig. 20—Small Trocar and Acupuncture or Exploring Needle (for testing the character of ambiguous swellings or fluid collections about the rectum).] The chief discomfort to a patient with fistula is the discharge, in greater or less quantity, of purulent or muco-purulent matter which is kept up from the sinus so long as it remains unhealed, soiling the linen and making it wet and uncomfortable, and producing an excoriation of the nates. The discharge is not of itself sufficient to be a source of great exhaustion, and does not interfere with ordinary occupations, so that many patients have had fistula for a considerable length of time without being conscious of any serious ailment. The escape of flatus and mucus from the bowel in complete fistula will often prove a source of annoyance, as will also the passage of feculent matter which will be expelled through the sinus should the fistulous channel be very free. An attack of secondary suppuration is always liable to complicate the presence of a fistula, and is usually due to a stoppage of the track by small particles of feces or by exuberant growth of the granulations. Such a sequela, of course, is attended with pain, until a new opening forms or one is made by the surgeon. In some cases the original fistulous track becomes reëstablished. Fistula in some persons, particularly those of a nervous temperament, produces an impression of physical imperfection and weakness in their organization, which renders them miserable. As in other affections of the rectum, various reflex or sympathetic pains are experienced in cases of fistula; they are referred to the back, to the loins, and to the bottom of the abdomen. When such pains extend down the leg and to the foot, they are likely to be attributed to sciatica unless the history of the case is carefully studied and a critical examination made.