_The first symptom_ is the desire to chew, lick or eat indigestible or filthy substances. Horses and cattle may stand and lick a board for an hour or more; cattle may chew the long hair from the tails of horses; sheep may nibble wool; sows may within a short time after giving birth to their pigs, kill and eat them; chickens may pick and eat feathers. Innutrition may accompany the abnormal appetite, as very frequently the affected animal shows a disposition to leave its feed in order to eat these injurious and innutritions substances. In ruminants, the wool or hair may form balls and obstruct the opening into the third compartment, causing chronic indigestion and death. _The treatment_ consists in the removal of the cause. Feeding a ration that meets the needs of the system, clean quarters and plenty of exercise are the most important preventive lines of treatment. In such cases medicinal treatment (saline and bitter tonics) may be indicated. It is usually advisable to remove the affected animals from the herd or flock in order to prevent others from imitating them. DISEASES OF THE STOMACH There is a remarkable difference in the development of the stomachs of solipeds and ruminants. The horse's stomach (Fig. 8) is simple and has a capacity of three or four gallons. The left portion is lined with a cuticular mucous membrane, and the right portion with a glandular mucous membrane that has in it the glands that secrete the gastric juice. The most important digestive change in the feed is the action of the gastric juice on the proteids and their conversion into the simpler products, proteoses and peptones. [Illustration: FIG. 8.--Photograph of model of horse's stomach: left portion, oesophagus, right portion, and intestine.] [Illustration: FIG. 9.--Photograph of model of stomach of ruminant: rumen, reticulum, omasum, and abomasum.] [Illustration: FIG. 10.--A section of the wall of the rumen and reticulum, showing the oesophageal groove: lips of groove; opening from oesophagus; and opening into omasum.] RUMINANTS have a compound stomach (Figs. 9 and 10). The capacity of the stomach of the ox is between twenty and thirty gallons. The four compartments into which it is divided are the rumen, reticulum, omasum, and abomasum or true stomach. The rumen is the largest compartment, with a capacity of more than twenty gallons. The reticulum is the smallest, with a capacity of about one-half gallon.