6. An important influence seems also to be exerted by the liver upon the saccharine matters derived from the alimentary canal. The chief purpose of the saccharine and amylaceous principles of food is, in relation to respiration and the production of animal heat. The pancreas is a long, narrow, flattened gland of a reddish-cream color, larger at one end than at the other, and lying behind the stomach opposite the first lumbar vertebra. It is usually from 6 to 8 inches long, about 1 1/2 inch in average width, and 1/2 to 1 inch in thickness. It weighs about 2 1/4 to 3 1/2 ounces. Its principal excretory duct is called the pancreatic duct, and runs through the entire length of the gland from left to right. The duct opens in a common orifice with the ductus communis choledicus on the inner surface of the duodenum about 4 inches below the pylorus. Healthy pancreatic juice is a clear, viscid fluid, frothing when shaken. It has a very decided alkaline reaction. The pancreas in its minute anatomy closely resembles the salivary glands; and the fluid elaborated by it appears almost identical with saliva. The composition of pancreatic juice is: Water, 980.45 Solids, 19.55 The solids are: Pancreatic, 12.71 Inorganic bases and salts, 6.84 ----- 19.55 Action of pancreatic juice. (1) It acts on starch raw and boiled with great energy, rapidly converting it into grape sugar. (2) On proteids (meats) it also exercises a solvent action, so far similar to that of gastric juice that by it the proteids are converted into peptones. (3) On fats pancreatic juice has a twofold action: it emulsifies them, and it splits up neutral fats into their respective acids and glycerine. Thus pancreatic juice is remarkable for the power it possesses of acting on all food-stuffs--on starch, fats, and proteids. Succus entericus (intestinal juice). The precise action of this is not known. It has been said to act upon starch, to convert proteids into peptones, and to emulsify fats. On the other hand, each of these actions has been denied. The portal system of veins. The portal vein, or vena porta, collects the blood from the stomach, intestines, pancreas, and spleen; and carries it to the liver, from which the bile is secreted; ramifying after the manner of an artery in the substance of the liver and conveying to the capillaries of that organ the blood collected in the main trunk. This blood, together with that of the hepatic artery, after having served for the secretion of the bile and the nourishment of the liver, is withdrawn from that organ by the hepatic veins, and carried by them into the vena cava inferior.