_The large intestine_ is formed by the following divisions: caecum, double colon, floating colon and rectum. The caecum is a large blind pouch that has a capacity of about seven gallons. The double colon is the largest division of the intestines. It is about twelve feet in length and has a capacity of about eighteen gallons. This portion of the intestine terminates in the region of the left flank in the floating colon. The latter is about ten feet in length and about twice the diameter of the small intestine, from which it can readily be distinguished by its sacculated walls. The rectum is the terminal portion of the intestinal tract. It is about one and one-half feet in length and possesses heavy, elastic walls. Fermentation and cellulose digestion occur in the caecum and double colon. It is in the floating colon that the faeces are moulded into balls. The faeces are retained in the rectum until defecation takes place. The _intestinal tract of cattle_ is longer than that of solipeds and the different divisions are not as well defined as in the horse's intestine and about one-half its diameter. The large intestine is about thirty-five feet in length and its capacity six or seven gallons (Fig. 15). ACUTE INTESTINAL INDIGESTION OF SOLIPEDS.--Acute indigestion is more common in horses and mules than it is in any of the other domestic animals. Because of the difference in the causes and symptoms manifested, we may divide it into the following forms: spasmodic, flatulent and obstruction colic. _The predisposing causes_ are general and digestive debility resulting from the feeding of an insufficient or unsuitable ration, and general and parasitic diseases of the intestine. Nervous, well-bred horses are most susceptible to nervous or spasmodic colic. _The direct causes_ are improper methods of feeding and watering; giving the animal severe or unusual exercise immediately before or after feeding; the feeding of spoiled or green feeds and new grains; chilling of the body; imperfect mastication of feed because of defective teeth; obstruction of the intestine by worms. The feeding of grain at a time when the animal is not in fit condition to digest it results in imperfect digestion in both the stomach and intestine. This leads to irritation of the intestine and abnormal fermentation of its contents. The drinking of a large quantity of water immediately after feeding grain flushes at least a part of the undigested grain from the stomach through the small intestine and into the caecum. New grains, such as new oats, are hurried along the small intestine and reach the large intestine practically undigested. The two latter conditions are common causes of _flatulent_ or _wind colic_. Sudden change in the ration, especially to a green feed, may result in intestinal irritation and flatulence. [Illustration: FIG. 15.--Photograph of model of digestive tract of ruminant: oesophagus; rumen; reticulum; omasum; abomasum; small intestine; and large intestine.]