MUCOUS MEMBRANE LIVER. 83 



which it lines, what the skin is to the surface of the body. 

 It is an internal skin, which is a continuation of the external. 

 Like the skin, it is an organ of absorption and secretion. 

 It is composed of a corium or true skin and a sort of epi- 

 dermis, named the epithelium, variable in its texture and in 

 its elements according as it is to offer more or less resistance. 

 A peculiar fluid mucus is secreted by this membrane and 

 preserves its softness. The mucous membrane is covered, 

 throughout the digestive canal, even to the end of the small 

 intestine, with great numbers of papillae or villi, and espe- 

 cially on the tongue. In the stomach it has numerous folds, 

 which are effaced when the organ is distended; and through- 

 out the smaller intestine it forms the valvitla conniventes, 

 wrinkles or folds designed to increase the extent of absorbing 

 surface. 



The liver is an organ of a glandular nature, arid, like all 

 the glands, is designed to secrete a peculiar fluid. It 

 separates from the blood the elements which constitute bile. 

 Situated in the right hypochonder, it enters the arch of the 

 diaphragm ; and it occupies also a portion of the epigastrium, 

 and then comes in contact with the stomach, the arch of the 

 colon, &c. ; behind, it corresponds to the vertebral column, 

 the aorta, and the descending vena cava ; in front to the base 

 of the chest. It is held in its place by ligamentous folds of 

 the peritoneum; the most important of these is the suspen- 

 sory ligament. The form of the liver is difficult to describe : 

 its upper surface is convex, its lower slightly concave. It is 

 divided into the right and left lobes; to the latter is attached 

 an appendage named lobus Spigelii or Spigel's lobe. The 

 under surface of the liver is marked by the longitudinal and 

 transverse fissures. Through this last the portal vein enters. 

 Examined en masse, the liver is of a reddish-brown colour. 

 Its substance is yellowish, granular, and contained in an 

 envelope of cellular tissue called Glissorfs capsule. Several 

 kinds of vessels are found in it: the hepatic artery, which 

 carries the blood which nourishes the organ; the portal vein, 

 which carries the blood to the liver which is to be purified; 

 the hepatic vein, which transmits to the descending vena cava 

 the blood elaborated by the gland; and lastly, the bile-ducts^ 



