DIGESTION OF POOD. 31Y 



increase in the quantity of bile secreted, followed by a sudden 

 diminution, then a more gradual rise, with a subsequent fall. 

 Almost the same holds for the pancreas. 



It seems impossible to explain these facts, especially the 

 first rapid discharge of fluid apart from the direct influence of 

 the nervous system. 



Upon the whole, the evidence seems to show that the press- 

 ure in the bile-ducts is greater than in the veins that unite to 

 make up the portal system; but there are difficulties in the 

 investigation of such and kindred subjects as regards the liver, 

 owing to its peculiar vascular supply. It will be borne in mind 

 that the liver in mammals consists of a mass of blood-vessels, 

 between the meshes of which are packed innumerable cells, and 

 that around the latter meander the bile capillaries; that the 

 portal vein breaks up into the intralobular, from which capil- 

 laries arise, that terminate in the central interlobular veins, 

 which make up the hepatic veinlets or terminate in these vessels. 

 But the structure is compUcated by the branches of the hepatic 

 artery, which, as arterioles and capillaries, enters to some extent 

 into the formation of the lobular vessels. 



A question of interest, though difficult to answer, is the 

 extent to which the various constituents of bile are manufact- 

 ured in the Uver. Taurin, for example, is present in some of 



Fia. 258.— Lobnles of liver, interlobular vessels, and intralobular veins (Sappey). 1,1, 

 1, 1, 3, 4, lobules; 2, 3, 2, 2, intralobular veins injected witb white; 5, 5, 5, 5, 5, in- 

 tralobnlar vessels filled witb a dark injection. 



