CHAPTEE X. 



THE BILE. 



THE first peculiarity of the liver, as compared with other secreting 

 organs, is that it is supplied with blood at the same time from two dif-' 

 lerent sources ; namely, from the hepatic artery and the portal vein. 

 The ramifications of the hepatic artery are especially distributed to the 

 walls of the hepatic ducts, to those of the portal vein, to the capsule of 

 Glisson, and to the peritoneal covering of the organ ; while those of the 

 portal vein pass in a peculiar manner into the glandular parenchyma, 

 and after traversing its substance as a capillary plexus become continu- 

 ous with the rootlets of the hepatic vein. Beside arterial blood, accord- 

 ingly, which it receives in common with the other abdominal organs, 

 in moderate quantity, it is supplied with an abundance of venous blood, 

 collected by the portal system from the stomach, the spleen r the pancreas 

 and the intestinal canal. 



Secondly, the liver is distinguished by its large size. While the 

 weight of all the salivary glands taken together, in the human species, 

 is but little over 100 grammes, and that of the pancreas about 75 

 grammes, the liver forms a compact vascular and glandular organ, 

 weighing nearly or quite 1600 grammes, and occupying a considerable 

 portion of the abdominal cavity. 



Lastly, the liver is peculiar in its texture, and differs so much in this 

 respect from the other secretory organs, as to require a special descrip- 

 tion. As in other instances, the secreting apparatus consists essentially 

 of glandular cells and capillary bloodvessels, with the ducts which col- 

 lect and transport the secreted fluid ; but these elements, instead of 

 being arranged as elsewhere in distinct groups of tubular or rounded 

 follicles, are closely united with each other, forming on all sides a con- 

 tinuous mass by their mutual contact and adhesion. 



The substance of the liver, in man and in the quadrupeds generally, 

 is divided into pentagonal or hexagonal masses or islets, about 1.5 milli- 

 metre in diameter, which are known by the name of the hepatic lobules. 

 These lobules, however, are not distinctly separated from each other, 

 but are simply made visible by the relative arrangement of the afferent 

 and efferent bloodvessels. Each lobule is embraced upon its external 

 surface by the terminal branches of the portal vein, which ramify be- 

 tween the lobules lying adjacent to each other. These vessels are 

 accordingly known as the interlobular veins. From the side of the 

 interlobular vein, minute vessels pass into the substance of the lobule, 

 and there form by their division and inosculation an abundant capillary 

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