The same _coats_ continue in the small intestine as were found in the stomach, but they are here much thinner and the inner coat is shaggy, like velvet, with innumerable minute processes called _villi_, which greatly increase the absorbing surface. In fact, the great length of the intestine as well as the presence of the villi is aimed to provide a large surface to absorb the food as it passes, an even greater increase of surface being provided by the fact that the intestinal wall is thrown into folds, the _valvulæ conniventes_. Each villus is covered with a layer of columnar epithelial cells and has within connective tissue, in which are found a fine capillary network and open lymph spaces from which leads a single lacteal vessel. Closely connected with the lymphatic vessels are the _solitary glands_, small round bodies the size of a small pin’s head. _Peyer’s glands_ or _patches_ are patches of solitary glands opposite the mesenteric attachment and are largest and most numerous in the ileum. In typhoid fever they are involved and may become the seat of ulcers. There are also the _glands of Lieberkühn_ which secrete the succus entericus. The _arteries_ of the small intestine, which include the superior mesenteric, are from the celiac axis and the _nerves_ are from the superior mesenteric plexus of the sympathetic. The _veins_ empty chiefly into the portal system. The _movements_ of the intestine, like those of the esophagus, are peristaltic, but the action is complicated by the fact that the tube is not straight but in coils. =Intestinal Digestion.=--The food, which enters the duodenum as chyme, there comes in contact with the bile and the pancreatic juice, which together but unmixed enter the duodenum from their respective ducts by a common orifice. As in the stomach, the digestive juices are called forth by the presence of food. The _bile_ is secreted in the liver, from which it flows away through the hepatic duct, which joins the cystic duct from the gall-bladder to form the common bile duct. Through this it flows into the intestine during digestion, but between whiles it passes up into the gall-bladder, where it is stored for future use and whence it is expelled when needed. When pure it is a thick, viscid liquid, varying from a bright red to a greenish-yellow in color according to the pigments present, and of an alkaline reaction. It consists chiefly of the bile pigments, _biliverdin_, which gives the green color, and _bilirubin_, which gives the red color, and of bile salts in solution, _cholesterin_, which probably forms the basis of many gall stones, is also present. Bile is a disinfectant to the bowel and a lubricant for the feces. How much digestive action it has is a question, but it affords the necessary alkaline medium for the pancreatic juice to act in.