been proved, that urea, the end-product of protein metabolism, which is brought by the blood to the kidneys and there excreted, is formed in the liver. At any rate, urea is formed not only from the nitrogenous food eaten but from the metabolism of protein substances in the tissues, being purely a waste product, from which the nutritious substances have been absorbed. The amount thrown off is an accurate gauge of the amount of protein metabolism going on. The process of its manufacture is doubtless very complex.
Ptosis or dropping of the liver sometimes occurs and is due to the stretching of the ligaments. Rupture is common, generally as the result of a fall from a height, on account of its size and friability. The liver is also subject to many diseases. Cirrhosis occurs in people who drink a good deal and in its later stages is accompanied by ascites, an accumulation of fluid in the abdominal cavity. When there is a general accumulation of fluid throughout the body it is known as anasarca. Syphilis causes enlargement of the liver. Abscesses occur, perhaps oftener in the tropics than farther north, and may break into the lungs, stomach, or intestine.
The Gall-bladder.—The gall-bladder, which is simply a reservoir for the bile, is a pear-shaped organ three inches long and one inch broad. It lies in a fossa on the under side of the liver, with the large end or fundus touching the abdominal wall just below the ninth costal cartilage. Here it can be felt as a small mass in empyema of the gall-bladder. Normally it holds a little over one ounce, but with occlusion it may become stretched. Its duct is the cystic duct, which joins the hepatic duct in the common bile duct, but bile only passes up into the gall-bladder when the opening into the duodenum is closed, that is, between meals.
If one of the bile ducts is stopped up by a stone or cancer or for any other cause, the bile backs up in the liver, the pigments are absorbed into the circulation,
