CHAP. XXV.] FUNCTION OF THE LIVER. 251 



We may therefore conclude that the pancreas secretes a fluid of 

 which the office is, first and specially, to digest fatty and oily ele- 

 ments; and, secondly, to convert starch into sugar, and thus to 

 promote the digestion and absorption of amylaceous food. 



The Function of the Liver. The liver is the largest gland in the 

 body. It is remarkable not only for its complex structure, which 

 will be described in the chapter on Secretion, but also for its 

 peculiar double circulation. It is supplied with blood from two 

 sources, namely, from the hepatic artery, which carries red blood 

 to it, and is distributed mainly to the coats of the ducts ; and from 

 the vena portce, a vein in structure, but an artery in its mode of 

 branching, which conveys a large quantity of dark blood, derived 

 from the veins of the stomach, the intestines, the pancreas, and the 

 spleen, and which ramifies throughout every part of the liver, 

 passing into a dense capillary plexus, whence it is taken up by 

 the hepatic veins, and carried to the right side of the heart. By 

 this arrangement, all matters absorbed into the blood from the 

 gastro-intestinal surface, must pass through the liver, a point of 

 anatomy which indicates that the material added to the blood by 

 absorption from the stomach and intestines, in some way contributes 

 to support the function of this gland. 



We may justly assume that the bile is secreted from the blood of 

 the vena portae, because of the great size of that vessel, and the vast 

 extent of the capillary plexus, which it supplies, more especially as 

 the small size of the hepatic artery, compared with the great bulk 

 of the gland, and the trifling degree to which it can contribute 

 to the formation of the capillary plexus of the organ, clearly 

 disqualify it for contributing to the secreting process. 



The bile, as a separated product, first shows itself in the minute 

 canals or ducts which originate in the substance of the liver, and 

 which, by frequent successive junctions, form two large ducts, each 

 somewhat larger than a crow-quill, which emerge at the transverse 

 fissure of the liver, the one from its right, the other from its left 

 lobe. These two ducts pass for a short distance downwards and 

 inwards, enveloped by Glisson's capsule, along with the trunks of 

 the hepatic artery and portal vein, and with the hepatic plexus of 

 nerves, and several large lymphatics, with some lymphatic glands. 

 About an inch below their emergence, they unite at an acute angle, 

 and form a single duct, a little larger than either; this is the hepatic 

 duct, which soon unites with a short duct proceeding from the gall- 

 bladder, the cystic duct. The union of these two ducts forms the 



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