ITS FORMATION. 83 



also does the source of the substances which are conveyed into 

 the portal blood, point to the peculiar function of the liver as a 

 metamorphosing organ. The venous blood proceeding from the 

 stomach, the whole intestinal canal, and from the mesentery, is 

 collected in the portal vein ; hence a great part of the nutrient 

 matters absorbed in large quantity by the veins of these parts is 

 conveyed into the liver; moreover the veins of the pancreas, 

 and (what is more essential) those of the spleen, pour their blood 

 into the portal vein. We shall presently see, when treating of the 

 chemical and physical investigation of the blood, that the character 

 of the portal blood varies according as the portal vein receives 

 most of its blood from the stomach and intestinal canal during the 

 process of digestion, or from the splenic veins, which convey a 

 fluid very different from other venous blood. We shall, however, 

 also see that the blood of the hepatic veins is as different from 

 portal blood (whether collected during fasting or while the diges- 

 tive process is going on) as from the blood of any other portion of 

 the venous system. The blood within the liver, in its transition 

 from the arterial into the venous state, undergoes more striking 

 alterations than in any other organ. These changes are not con- 

 fined to the mere abstraction of individual constituents from the 

 blood in the liver, but, as we shall presently see, some of its con- 

 stituents have undergone very distinct chemical changes. To this 

 we must add, that the presence of the most important constituents 

 of the bile cannot be recognised as pre-formed in the portal blood, 

 notwithstanding many assertions to the contrary : at all events I 

 have never succeeded in detecting them, even when operating on 

 very large quantities. 



The principal arguments against the view that the bile is formed 

 from heterogeneous constituents within the liver itself, are based 

 partly on the supposed analogy between the biliary and the renal 

 secretions, and partly on certain pathological phenomena. That 

 the analogy between the renal and hepatic secretions is limited to 

 the single fact that they both are secretions, is sufficiently obvious 

 from what is known regarding the difference in the structure of 

 the two organs ; and in reference to the facts derived from patho- 

 logy, these, upon the whole, rather accord with the view that the 

 bile is formed in the hepatic cells than that its actual constituents 

 pre-exist in the blood. Jaundice very seldom occurs in diseases 

 of the parenchyma of the liver, and almost never in the different 

 forms of fatty degeneration or in tuberculosis of the liver, and 

 very rarely in simple and red atrophy, in granular liver, and hepa- 



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