The liver is the largest glandular organ in the body; its office is to secrete bile. It is oblong and oval in shape, and occupies the position on the right side, under the lower ribs. It weighs from four to five pounds; it measures from ten to twelve inches transversely, and from six to seven antero-posteriorly; its greatest thickness is from four to five inches. On the upper surface it is convex, and on the lower concave. Its color is of a reddish-brown, with occasional spots of black.

The under surface of the liver presents a deep fissure, called umbilical or longitudinal, reaching from the anterior to the posterior notch, containing the remains of the umbilical vein of foetal life. Sometimes this fissure is converted into a foramen, or opening, the right and left lobes being connected. At right angles to this fissure is another, called the transverse fissure, containing the portal vein, hepatic artery, and hepatic duct, bound together by the capsul of Glisson, a membrane of cellular tissue. The gall-bladder lies in a deep depression upon the under surface of the right lobe of the liver. The lobulus quadratus is that portion of the liver included between the depression occupied by the gall-bladder and the longitudinal and transverse fissures. At the posterior and inferior portion of the liver is a triangular lobe called the lobulus Spigelii. The elongated ridge running from the lobulus Spigelii outwardly is the lobulus caudatus. These lobules are, however, all contained in the two lobes of the liver. The right lobe is the largest and thickest, and the left terminates in a thin cutting edge. The structure of the liver may be seen by tearing the liver of any animal. This will show a granulated arrangement, and each of these granules is usually called an acinus. These acini consist of a terminal branch of the portal vein and hepatic artery, together with the incipient radicles of the hepatic duct and hepatic vein, and in the capillary network thus constituted are numerous cells, which secrete the bile.

The liver is liable to a variety of disorders, and, when affected, exerts a marked influence on the organs and tissues of the body. The functions of the organ are so important that impairment arising from any organic cause quickly disturbs the harmony and health of the whole economy. Its office is to eliminate the superfluous carbon from the blood. This carbon enters into chemical combination with other substances, forming the compound known as bile, and which is poured into the duodenum, or upper bowel, where it assists greatly in the process of digestion.