The effect upon the liver of impediments to the outflow of bile such as those above indicated is in the first place an increase in its size, the whole biliary passages and the liver cells being distended with retained bile. This enlargement, however, speedily subsides when the obstruction is removed, but should it persist the liver ultimately shrinks and undergoes atrophy in its whole texture. The bile thus retained is absorbed into the system, and shows itself by the yellow staining seen to a greater or less extent in all the tissues and many of the fluids of the body. The kidneys, which in such circumstances act in some measure vicariously to the liver and excrete a portion of the retained bile, are apt to become affected in their structure by the long continuance of jaundice. The symptoms of obstructive jaundice necessarily vary according to the nature of the exciting cause, but there generally exists evidence of some morbid condition before the yellow coloration appears. Thus, if the obstruction be due to an impacted gallstone in the common or hepatic duct, there will probably be the symptoms of intense suffering characterizing hepatic colic (see COLIC). In the cases most frequently seen--those, namely, arising from simple catarrh of the bile ducts due to gastro-duodenal irritation spreading through the common duct--the first sign to attract attention is the yellow appearance of the white of the eye, which is speedily followed by a similar colour on the skin over the body generally. The yellow tinge is most distinct where the skin is thin, as on the forehead, breast, elbows, &c. It may be also well seen in the roof of the mouth, but in the lips and gums the colour is not observed till the blood is first pressed from them. The tint varies, being in the milder cases faint, in the more severe a deep saffron yellow, while in extreme degrees of obstruction it may be of dark brown or greenish hue. The colour can scarcely, if at all, be observed in artificial light. The urine exhibits well marked and characteristic changes in jaundice which exist even before any evidence can be detected on the skin or elsewhere. It is always of dark brown colour resembling porter, but after standing in the air it acquires a greenish tint. Its froth is greenish-yellow, and it stains with this colour any white substance. It contains not only the bile colouring matter but also the bile acids. The former is detected by the play of colours yielded on the addition of nitric acid, the latter by the purple colour, produced by placing a piece of lump sugar in the urine tested, and adding thereto a few drops of strong sulphuric acid. The contents of the bowels also undergo changes, being characterized chiefly by their pale clay colour, which is in proportion to the amount of hepatic obstruction, and to their consequent want of admixture with bile. For the same reason they contain a large amount of unabsorbed fatty matter, and have an extremely offensive odour.