When a sinus exists from the inflamed and perforated pelvis, or an abscess connected with the kidney has been recently opened, it may be dilated or enlarged by incision sufficiently to allow the passage of an exploring finger and forceps. The large arterial and venous branches which surround the pelvis make it safer to trust rather to dilatation or {52} tearing to get through to its interior than to incision, which must, if necessary, be practised with great care. Experience has shown that an incision can be made through the renal substance without great danger, the hemorrhage being chiefly venous. This incision has been made in several cases, and where the secreting portion is much atrophied is obviously of still less consequence than in the healthy kidney. After the removal of the calculus, drainage may be established for a time until the pelvis has resumed its normal condition or the purulent discharge has diminished. If no sinus exists, but a diagnosis has been clearly made, or even if symptoms of sufficient severity exist to justify a strong suspicion and decisive treatment, an incision may be made along the edge of the erector spinæ or the great mass of muscle attached to the spinal column and passing through the quadratus lumborum. An incision outside of the quadratus lumborum will come upon the kidney, but too far outside to make a direct access to the pelvis practicable. If it be known, however, that the cut must be made through the kidney itself, then the primary incision through the skin may be made in the exterior line, and will be less deep. Measuring along the last rib two inches from its extremity, and then at right angles an inch and a half downward and inward, will indicate a point at which a puncture will reach the renal pelvis. This may be made the central point of an incision, though it is often necessary to utilize the whole space from the last rib to the crest of the ilium. After reaching and exploring the kidney with the finger, the incision may be carried cautiously through the pelvis and enlarged by dilatation or tearing. In order to feel the calculus it may be necessary to have counter-pressure made from the front of the abdomen in order to lift or fix the kidney, and a case has been mentioned where the finger, having failed to reach a calculus behind, was carried around and in front of the kidney with success. If the calculus is too large or too irregular to be removed whole, it may be broken and extracted piecemeal.