The distention of the bile-ducts is not limited to those situated external to the liver, but also affects those in the substance of the organ; and to such an extent may this be the case, that, on making a section of a liver that has long had its common duct obstructed, a number of large excavations are observed all over its surface, which excavations are nothing more than the open mouths of the transverse sections of the dilated ducts. Such a state of matters is tolerably well represented in the section of the liver in Plate I. Further, the effect of this obstruction to the exit, and consequent accumulation of the biliary secretion, is not confined to the mere distention of the ducts, but causes various changes to occur in the parenchyma of the liver itself. The first of these is an increase {48} in the size of the organ, arising partly from the accumulation of the bile, and partly from the congestion caused by the pressure exerted on the vessels by the distended ducts. In the second place, gradually as the state of matters here described progresses, the parenchyma of the organ becomes itself affected, partly from the direct pressure exercised upon it, and partly from the derangement of its nutrition, produced by the interruption to the hepatic circulation; so that, after a time, the enlarged liver slowly, and by degrees diminishes, until it at length regains its natural size, thereby rendering, at this period of the disease, the diagnosis of the case extremely difficult. This state of matters is not, however, of long duration; for, in consequence of the continued compression of the blood-vessels and parenchyma, the nutrition of the liver is so disordered, as to lead to a gradual shrinking of the entire substance, or, in other words, to a general atrophy of the organ. It is thus seen how in _permanent occlusion_ of the common gall-duct the liver may be found _hypertrophied_ in the _first_, of _normal dimensions_ in the _second_, and _atrophied_ in the _third_ and _last stage_ of the disease. In cases of the kind here described, it is not at all unlikely that the enlargement of the liver in the earlier, as well as its atrophy in the later {49} stages of obstruction, may be mistaken for the cause of the jaundice, instead of the result of the arrest of the flow of bile, and thereby lead to a grave error in treatment. The history of the case, together with a knowledge of the above facts, will, however, tend to facilitate the diagnosis. Thus, it must be ascertained:-- Firstly,--If the jaundice preceded the alteration in size of the organ. Secondly,--If there is an absence of any history of hepatitis; and, Thirdly,--If there is no evidence of any pulmonary or cardiac mischief likely to lead to passive congestion of the hepatic tissue.