We came now to speak of another anatomical element in the structure of the Ever: As the bile ducts increase in size they contain numerous follicles and cluster-likc glands -which are called racemose (the biliary acini of Robin), and they continue to occupy the biliary passages as far as the (ludas C01107110d8 ChOled0C101A, or the common bile duct which empties into the intestinal canal. Those which are found in the smallest ducts are simple follicles from lat to w*D of an in. hi length. The larger of these glands are formed of groups of these follicles, and are from aD tO Th of an in. in diameter. The nutrition of the liver is provided for by the hepatic artery, whose distribption is exceed" ingly interesiing. It has three sets of branches. As soon as it enters the sheath formed by the capsule of Glisson, it sends off very line branches, called vassa vassorum, to the walls of the portal veiri, to those of the hepatic vein, to its own branches, and an .exceedingly rich and beautiful net-work of branches to the hepatic duct. When the hepatic artery is well injected it almost completely covers the duct with.its ramifications. The hepatic duct proper, or that single vessel so called lying outside of the liver, is formed by the union of two ducts, one from the right and one from the left lobe of the liver. It is about an inch and a half long, and joins the duct frotn the gall-bladder, called the cystic duct, to form the common duct, or duclus COMMUlti8 choledochus, which. is about three inches long and of the size of a goose-quill, and empties, in common with the pancreatic duct, into the intestine, a little below the middle of the duodenum, or about 5 in. below the stomach. The gall-bladder is an elongated, pear-shaped sack about 4 in. in length and one in breadth, having a capacity of about one and a half fluid ounces. The cystic duct, connecting it with the hepatic duct, is the smallest of tho three larger ducts, and is about one inch in length. In the gall-bladder there are also numerous small racemose glands similar to those above mentioned as existing in the biliary ducts generally. They consist each of froin 4 to 8 follicles lodged in the submucous tissues. They secrete mucus mixed with bile. The idea has been .entertained by some that these binary racemose glands found in different parts of the biliary ducts were the bile-producing glands, while the hepatic cells were the organs for secreting sugar, or, in other words, for the conversion of the glycogenic matter of the liver into glucose, or grape-sugar; but this view has not been found tenable. The nerves of the liver are derived from the pneumogastric, the phrenic, and from the solar plexus of the great sympathetic. They all.penetrate the gland at the great transverse fissure, and follow the blood-vessels in their course of distribution to the various parts of the organ, but their terminal distributions are not yet well understood. The lymphatic vessels of the liver are numerous and consist of two layers. The outer or superficial layer is situated immediately beneath the serous or peritoneal covering. The inner or deeper layer forms a plexus surrounding the lobules, having entered the liver along with the portal veins, hepatic arteries, and bile ducts, enveloped in sheaths of Glisson's capsule. In their course they invest the branches of both ducts and blood-vessels with a delicate net-work of tubes, and ou arriving at the surface of the lobules they enter them and form another remarkable net-work of lymphatic passages, traversing the lobule iu every direction. Every blood capillary is enveloped in a lymphatic sheath in very much the same 'flannel. that the interlobular vessels are enveloped in the sheath of Glisson's capsule. These lymphatic sheaths surrounding the other vessels are other wise called the perivascular lymphatic spaces, and are similar in structure to those which are found in various other parts of the body. See LYMPHATICS.
The two distinct functions, that of the production of bile and the formation of sug-ar, which are now,generally recognized as being performed by the liver have led some physiologists to suppose that this gland is composed of two distinct portions or anatomi cal elements, and Robin has adopted this theory and calls one portion of the liver a biliary organ, and the other a glycogenic or sugar-forming organ. The lobules and
bepatic cells, with their different vessels, he regards as performing the glycogenic func tion, and the little racemose glands which are attached to the biliary ducts along their course as the bile-producing organs; and others have entertained ideas of the independ cnce of the sugar-making and bile-producing portions of the organ. But from the fact that bile is commonly found in the lobulcs, and that the biliary capillaries are connected with the excretory biliary ducts, the conclusion seems to be unavoidable that the bile is formed in the lobules, and, moreover, by the hepatic cells. It, therefore, becomes a question as to what are the functions of the little racemose glands attached to the larger bile ducts. They have much the form of mucous glands in other portions of the body, and from the examinations of Sappey, who has found the bile to be viscid in proportion to the number of these glands in the ducts containing it, they appear to be really mucous glands. In the rabbit, an animal in which these glands are not found in this situation, the bile is quite fluid, and free from its ordinary viscidity. It has generally been thought that the bile is secreted exclusively from the blood which has been brought from the intestines by the portal vein, and that, indeed, the principal office of the liver was to separate effete matter from this portion of the venous system; but many experi ments which have been made since Bernard discovered the glycogenic function of the liver go to show this idea erroneous. It has also been thought that the hepatic artery may furnish material for the secretion of bile, while the portal vein fur nished that for the production of sugar; but these views again are quite overthrown by many well-established facts and experiments. It bas been found that, after the ligation of the hepatic artery, bile has been secreted from blood furnished by the portal vein; and again, according to the experhnents of Ore, who has succeeded in gradually obliterat ing the portal vein without immediately producing death, it has been found that bile is secreted from blood furnished by the hepatic artery. In one instance in which a patient died of dropsy the portal vein was obliterated, and y-et the gall-bladder was full of bile. Anomalous cases have been reported where the portal vein, instead of passing through the liver, emptied into the ascending vents cava, and where also there was found no deficiency of bile, These facts point to tho conclusion that the secretory elements of 'the liver have gla elective power, and that this gland may elaborate its products either from venous or arterial blood. The only conclusion, therefore, is that the liver pro duces bile from both the portal vein and the hepatic artery, and that the secretion may be kept up if either one of these vessels be obliterated. he natural color of bile is vari able; in the pig it is bright yellow; in the dog, dark brown; and in the ox, greenish yel low. In general, it may be stated that it is dark green in carnivorous, and greenish yellow in herbivorous animals. Its specific gravity is variously stated. Some author ities place it at 1026; others from 1020 to 1026; and again others from 1026 to 1031. These differences are considerable, but the numbers were probably the result of exact observation, as the bile is found to differ under different circumstances. See table. Fresh bile is nearly inodorous, but after being taken from the body of an animal it soon undergoes putrefactive changes. It has been generally thought to be invariably alkaline, and this is true of that which is found in the hepatic duct, but it often has an acid reaction after it has passed into the gall-bladder.