These and carcinoma are the main affections of the biliary passages. The latter is almost always secondary to pyloric cancer and involves the lymphatic nodes; metastatic deposits may also exist in the liver itself. The diagnosis between the two affections is sometimes difficult. Gall-stones are most frequent in the gall-bladder, next in the common duct, and lastly in the hepatic duct. Obstructive symptoms are not often observed from gall-stones in the hepatic duct alone. Obstruction of the common duct causes jaundice, but this is rare in obstruction of the cystic duct; practically, jaundice is only seen in obstruction of the common duct. Gall-stones usually form in the gall-bladder and, as the cystic duct is smaller than the common duct, if a stone gets out of the former it is frequently passed into the intestine. On account of the contracted opening of the common duct into the duodenum, stones are liable to be retained in the ampulla of Vater. This causes a damming back of the bile, and the common duct increases to the size of a finger. Very large gallstones may cause ulceration into the duodenum or colon or may press on the portal vein and vena cava, and produce ascites. In operating for gall-stones, Mayo Robson incised through the middle of the right rectus muscle and prolonged the upper part along the edge of the ribs to the outer side of the ensiform cartilage. Where more room was desired Bevan added a transverse cut outward from its lower end. Kocher made a curved incision 4 cm. (1 1/2 in.) below the edge of the ribs (see page 382). In order to make the liver project a hard roll is placed beneath the back. To bring the gall-ducts to the surface the liver is dragged down and its edge turned up over the upper extremity of the wound. The gall-bladder can be drawn out and this straightens the curves in the cystic duct. By placing one or two fingers in the foramen of Winslow the thumb can palpate the cystic and the common duct until it disappears behind the duodenum. Gall-stones in the second (retroduodenal) portion of the duct or in the ampulla of Vater can often be felt through the walls of the duodenum. If it is desired to gain access to this portion of the duct, the peritoneum on the outer side of the second portion of the duodenum, binding it to the posterior abdominal wall, must be divided. The duodenum is then turned to the left and the common duct followed down if necessary through the pancreas to the ampulla of Vater. Stones impacted in the ampulla of Vater can be removed by incising the front of the second portion of the duodenum and then cutting down on the stone through the papilla. In some cases it may be impossible to pass a probe down the cystic duct owing to its being caught by the valve-like folds of the mucous membrane. In removing the gall-bladder, bleeding will be less if the cystic artery be first clamped. If this is not possible, then the bleeding will occur from the branches on one or both sides of the gall-bladder. The peritoneum is to be cut through, not torn. Bleeding from the liver substance is slight and readily stopped by pressure. In incising the common duct for calculi the relation of the portal vein behind and the hepatic artery to the left should be remembered. These can be avoided by cutting down on the calculus.