The gastric, splenic and mesenteric veins, which collect the venous blood from all the digestive organs, unite to form the portal vein, which carries to the liver this blood which has circulated through the capillaries of the stomach, spleen, pancreas and intestines, and though dark in colour, is laden with nutriment, the products of digestion. This important vein breaks up into capillaries (after the manner of an artery), and distributes this blood by means of them throughout the liver ; it there mingles with blood supplied by the hepatic artery, and is collected again by small veins which unite to form the hepatic vein, by which it is carried to the inferior vena cava, and by it is poured into the right auricle.