_Definition._ Inflammation of the intestinal mucosa. _Causes._ Irritants of all kinds taken in with food, or as medicine or otherwise and acting on the mucosa. Debilitating conditions (chronic disease, starvation, overwork, close indoor life) which lower the tone of the system at large, and local debilitating conditions like coarse, dry, fibrous, innutritious food, congestions, parasitisms, impaired innervation and troubles of the circulation are strongly predisposing. Drinking iced water may operate by lowering the tone of the intestines but seems to habitually act rather by inducing reaction and congestion. Chills of the surface, especially when perspiring and fatigued, act in the same way. The relaxation and atony attending on long continued hot weather, predisposes to enteritis, but is doubtless even more injurious by the abundance of ferments which it propagates in food and water. Overfeeding and stimulating aliments thrown on an alimentary canal in such an atonic condition become especially hurtful. The injury, however, comes most commonly from food that contains an excess of cryptogams or bacterial ferments or from water similarly charged. Newly harvested fodders in which the microbes are still in a state of vigorous life, when added to the poisonous principles in certain immature seeds (leguminosæ, gramineæ, etc.); fodders that have undergone fermentative changes (rotten potatoes, turnips, musty hay or oats); fodders that are leafy and harbor an excess of microbes (alfalfa, sainfoin, cowpea, clover) are especially dangerous at times. If musty or otherwise altered they often contain besides, dangerous toxins. In taking into account the fungi and microbes in spoiled foods, we need not give exclusive attention to the particular species of microbe present. An extended observation shows that the same ferments may be present in the dry, well cured, wholesome fodder, and in the musty or spoiled specimen, the main difference being in the excess found in the latter case as compared with the former. With the excess too, there is always present a large amount of toxins, ptomaines and other more or less poisonous products, which, acting on the intestinal mucosa or even on the system at large, tend to reduce its vitality and to lay it open to the attacks of bacteria which had otherwise remained perfectly harmless. Porcher and Desoubry, Achard and Phulpin and Wurz have shown experimentally that intestinal microbes can enter the chyle and blood from even a healthy bowel. The streptococcus of pneumoenteritis equi of Galtier and Violet appears to be a common fodder and intestinal microbe, which has become pathogenic, because of its excess or on account of a lack of resistance on the part of the animal. In the same way the various intestinal cocci and the common colon bacillus may become pathogenic when the normal antagonism of the bowels and their contents is lessened.