=The Large Intestine= (Fig. 31, No. 12). _Location._—The large intestine extends in a straight line along the inferior border of the vertebral column communicating anteriorly with the small intestine, and the cæca and posteriorly with the cloaca. _Shape._—The diameter of the large intestine is approximately twice that of the small intestine. In fowls of average size its mean length is 4.61 inches. The large intestine has sometimes been spoken of as the rectum, or straight gut. _Structure._—Like the small intestine the large intestine has four coats: an inner mucous, a submucous, a middle muscular and an outer serous. The folds of mucous membrane of the large intestine have tubular glands lined with columnar cells (Fig. 37, _A_, No. 1). _Function._—The large intestine is similar in function to that of the small intestine, in that digestion and absorption may take place within it. =The Cæca= (Fig. 31, No. 11). _Location._—The fowl has two cæca extending forward from their point of origin at the juncture of the small and large intestine. _Shape._—The cæca average 7.61 inches in length. They are large in caliber toward the blind extremity and are constricted near their origin. _Structure._—The parietal coats are continued from the small intestine. Ebarth has described an elevated body in the cæcum, which is located about 4 millimeters from the opening and is composed entirely of lymphoid tissue. [Illustration: FIG. 37_A_.—Photomicrograph of a transverse section of large intestine and oviduct just anterior to the cloaca, showing the tubular glands of the large intestines, mucosa of oviduct with intervening structures. 1, The tubular glands of large intestine, or rectum. 2, Muscular wall of intestine. 3, Wall of the oviduct. 4, Mucosa of the oviduct. ] The cæca are usually partly filled with a soft pultaceous material of a pasty consistency. =The Cloaca= (Fig. 31, No. 13). _Location._—The rectum opens by a circular, valvular orifice into the dilated portion just in front of the anus, which dilatation is called the cloaca. _Shape._—The cloaca is saccular in shape. _Structure._—The cloaca is divided into two portions, the coprodeumal and the urodeumal. That portion of the cloaca into which the intestine empties is called the _coprodeum_; and the ureter and oviduct empty into the _urodeum_. The seminiferous tubules, carrying the semen from the testes in the male empty in teatlike projections on the cloacal mucous membrane into the urodeumal portion. The cloacal walls are similar in structure to the large intestines.