[Illustration:  Fig. 57.—­Tubular Glands of the Small Intestines.

A, B, tubular glands seen in vertical section with their orifices at C, opening upon the membrane between the villi, D, villus (Magnified 40 diameters)]

Attached to the caecum is a worm-shaped tube, about the size of a lead pencil, and from three to four inches long, called the vermiform appendix.  Its use is unknown.  This tube is of great surgical importance, from the fact that it is subject to severe inflammation, often resulting in an internal abscess, which is always dangerous and may prove fatal.  Inflammation of the appendix is known as appendicitis,—­a name quite familiar on account of the many surgical operations performed of late years for its relief.

The large intestine passes upwards on the right side as the ascending colon, until the under side of the liver is reached, where it passes to the left side, as the transverse colon, below the stomach.  It there turns downward, as the descending colon, and making an S-shaped curve, ends in the rectum.  Thus the large intestine encircles, in the form of a horseshoe, the convoluted mass of small intestines.

Like the small intestine, the large has four coats.  The mucous coat, however, has no folds, or villi, but numerous closely set glands, like some of those of the small intestine.  The longitudinal muscular fibers of the large intestine are arranged in three bands, or bundles, which, being shorter than the canal itself, produce a series of bulgings or pouches in its walls.  This sacculation of the large bowel is supposed to be designed for delaying the onward flow of its contents, thus allowing more time for the absorption of the liquid material.  The blood-vessels and nerves of this part of the digestive canal are very numerous, and are derived from the same sources as those of the small intestine.

146.  The Liver.  The liver is a part of the digestive apparatus, since it forms the bile, one of the digestive fluids.  It is a large reddish-brown organ, situated just below the diaphragm, and on the right side.  The liver is the largest gland in the body, and weighs from 50 to 60 ounces.  It consists of two lobes, the right and the left, the right being much the larger.  The upper, convex surface of the liver is very smooth and even; but the under surface is irregular, broken by the entrance and exit of the various vessels which belong to the organ.  It is held in its place by five ligaments, four of which are formed by double folds of the peritoneum.

The thin front edge of the liver reaches just below the bony edge of the ribs; but the dome-shaped diaphragm rises slightly in a horizontal position, and the liver passes up and is almost wholly covered by the ribs.  In tight lacing, the liver is often forced downward out from the cover of the ribs, and thus becomes permanently displaced.  As a result, other organs in the abdomen and pelvis are crowded together, and also become displaced.