Certain kinds of food are far more dangerous than others, and especially such as should be digested in the stomach. Thus the different grains—barley, rye, buckwheat, wheat, oats, Indian corn, and even bran, have been especially objected to. The amount of proteids in oats, for example, is 11.9 per cent., while those of hay are but 7 per cent. The same bulk of oats, therefore, demands nearly double the work of the stomach to reduce its nitrogenous constituents to peptones than does hay. But when fully insalivated the difference is even greater, for oats take but the equivalent of their own weight of saliva, whereas hay takes four times its own weight. There is 1 part of proteids in 16.7 parts of insalivated oats, and but 1 in 71.4 of insalivated hay. If the oats are bolted without mastication, which can never be the case with hay, the discrepancy becomes greater still. Grain is best fed often, in moderate amount, and without further loading of the stomach immediately with either solids or fluids. Above all never feed grain to a thirsty horse and then lead him direct to the watering trough. Even should he fail to have the stomach paralyzed by the cold water, and indigestion developed, yet much of the proteids will be washed out into the small intestine to threaten indigestion there. Selenitic waters may induce indigestion by neutralizing the hydrochloric acid of the stomach and interrupting digestion. Finally all forms of gastritis—catarrhal, toxic, and phlegmonous—induce atony, fermentation and indigestion. _Symptoms._ There may be simply tardy digestion or grave disorder with impaction or tympany. In the former case there is impairment or perversion of appetite, refusal of food, irregular feeding, licking earth or lime, or eating filth, even fæces, with some dullness, apathy, or signs of pain such as pawing with the fore feet, or looking round at the flanks. There is rumbling of the bowels, followed in favorable cases by the passage of flatus, of softened fæces containing imperfectly digested food, and distinct diarrhœa which proves curative.