As we have seen above, the liver receives an enormous amount of toxic products from the stomach and intestine, which it transforms or destroys. Like any other organ which is overworked, the liver may undergo certain changes when continually subjected to a strain, and great quantities of these toxins might be able, after a long-continued action, to alter the liver tissue. Such a condition we may note in gastric and intestinal diseases, especially in those cases where large amounts of fatty acids are formed. Bouchard found an enlargement of the liver in 23 per cent. of all his cases of dilatation of the stomach. We can understand that when fatty acids, as a result of gastro-intestinal disease, pass for a long time through the liver, they may destroy the delicate epithelium of this organ. Boix demonstrated this by experiments. By feeding animals with lactic, butyric, and acetic acids, he produced hepatic cirrhosis. So long as the liver is healthy it is able to withstand the constant inflow of toxins and will transform them into less harmful compounds. But when the liver is altered, as in cirrhosis, things are different. We then find a diminution of urea, and an increase of ammonia. Happily such a condition arises only when there are considerable anatomical and histological changes in the liver. Salaskin and Zaleski have shown in animals that when there are serious anatomical changes in the liver, the ammonia is increased, and the urea is diminished. We may suppose that in old age, when the connective tissue is more or less increased and important liver elements destroyed, a similar decrease in the urea formation may take place just as in chronic cirrhosis. That in diseases of the liver toxic products are formed and eliminated by the urine in increased amounts, has been shown by Professors Bouchard[181] and Roger. They found that the urine of patients suffering from diseases of the liver is more toxic than that of normal persons. Footnote 181: Leçons sur les auto-intoxications dans les maladies. That the normal urine is toxic has been proved by Séglas and Vauquelin,[182] and also by Bocci.[183] Bouchard has designated as the urotoxic unit the quantity of urine necessary to kill an animal weighing 1 kilogramme, and as the urotoxic co-efficient the relation of the urotoxin eliminated in twenty-four hours to the body weight of the animal. This latter, then, indicates the quantity of urotoxins a man eliminates in twenty-four hours. Footnote 182: Journal de Magendie, vol. ii, p. 357, 1822. Footnote 183: Centralbl. für med. Wiss. 51, 1882. All these calculations of Bouchard have had no great success, however, for many authorities, as Gumprecht,[184] Heymans v. d. Bergh, etc., have shown that the toxic effects of the injected urine may be explained in part by the difference in osmotic pressure between the injected urine and the blood. Footnote 184: Centralbl. für Inner. Med., 24, 1897.