The emulsification of fat is known to occur in the small intestine. By this process the fat is separated into minute particles which are suspended in water, but not changed chemically, the mixture being known as an _emulsion_. While this is believed by some to be an actual process of digestion, the advocates of the solution theory claim that it is a process accompanying and aiding the conversion of fat into fatty acid and glycerine.(63) *The Intestinal Juice* is a clear liquid with an alkaline reaction, containing water, mineral salts, and certain proteid substances that may act as enzymes. It assists in bringing about an alkaline condition in the small intestine and aids in the reduction of cane sugar and maltose to the simple sugars, dextrose and levulose. Since it is difficult to obtain this liquid in sufficient quantities for experimenting, its uses have not been fully determined. Recent investigators, however, assign to it an important place in the work of digestion. *Work of the Small Intestine.*—The small intestine is the most important division of the alimentary canal. It serves as a receptacle for holding the food while it is being acted upon; it secretes the intestinal juice and mixes the food with the digestive fluids; it propels the food toward the large intestine; and, in addition to all this, serves as an organ of absorption. Digestion is practically finished in the small intestine, and a large portion of the reduced food is here absorbed. There is always present, however, a variable amount of material that is not digested. This, together with a considerable volume of liquid, is passed into *The Large Intestine.*—The large intestine is a tube from five to six feet in length and averaging about one and one half inches in diameter. It begins at the lower right side of the abdominal cavity, forms a coil which almost completely surrounds the coil of small intestine, and finally terminates at the surface of the body (Figs. 2, 71 and 73). It has three divisions, known as the cæcum, the colon, and the rectum. [Fig. 73] Fig. 73—*Passage from small into large intestine.* At the ileo-cæcal valve is the narrowest constriction of the food canal. _The cæcum_ is the pouch-like dilatation of the large intestine which receives the lower end of the small intestine. It measures about two and one half inches in diameter and has extending from one side a short, slender, and blind tube, called the _vermiform appendix_. This structure serves no purpose in digestion, but appears to be the rudiment of an organ which may have served a purpose at some remote period in the history of the human race. The cæcum gradually blends into the second division of the large intestine, called the colon.