HO PHYSIOLOGY. 



and the left vagus has some fibers going to it. The whole organ is 

 insheathed in a very fine coat of areolar tissue known as Glisson's 

 capsule. 



Structure. 



The hepatic substance is readily torn and has a granular appear- 

 ance; these coarse granules, corresponding with the distinct spots 

 seen on the surface, are polyhedral, and are the lobules of the liver. 

 These lobules are 1 / 12 inch in diameter. In studying the relation of 

 these lobules to the blood-vessels and ducts of the liver, it is found 

 that an extreme branch of the hepatic vein commences in the axis 

 of every lobule and emerges at its base to join a larger branch. This 

 connection of veins and lobules reminds one of the attachment of the 

 leaves by their midribs and stems to the branches of trees. 



The capsule of Glisson divides the liver-substance into these 

 lobules, for the areolar tissue enters the transverse fissure of the liver. 



Microscopically, each lobule is made up of epithelial cells, natur- 

 ally spheroidal, but because of compression are more or less polygonal. 

 These, the true liver-cells, are about Viooo i ncn i n diameter, contain- 

 ing protoplasm with large, round nuclei which have one or more 

 nucleoli. The cells are held together by an albuminous cement-sub- 

 stance; in it are fine channels containing the bile-capillaries. 



The portal vein also has its course in the portal canals, where it 

 divides and subdivides. By its division between the lobules in the 

 interlobular connective tissue it forms the interl obular vein. From 

 this vein fine capillary branches are given off, which pierce the envelop- 

 ing membrane of the lobule to find their way toward its center in a 

 converging manner. In their course to its center they pass in close 

 proximity to the hepatic cells, and it is here that the real secretion of 

 the bile takes place. From the point of union of the capillaries in 

 the center of the lobule there proceeds a single, straight vein, called the 

 intralobular vein. Arrived at the base of the lobule, this vein empties 

 its contents into the sublobular vein, a radicle of the hepatic vein, 

 which empties into the inferior vena cava. 



The hepatic artery does not furnish the blood for the secretion of 

 bile. Its function is to furnish a blood-supply to Glisson's capsule 

 and to the investment of the lobules and the walls of the bile-ducts. 



The course of the bile-ducts is very similar to that of the portal 

 vein and hepatic artery. Bile capillaries have no distinct walls of 

 their own except those formed by the liver-cells between which they 

 are situated. All cells, except those in contact with capillary blood- 



