In connection with the gangrenous ergotism of cattle, the author has found on the same farms and feed, horses with ulcers on the buccal mucosa and gastro-intestinal indigestion. =Ergot= affects the seeds in nearly all the small graminaeæ and is produced by the _claviceps purpurea_ which first attacks the ovary of the seed (_sphacelia_ stage), then it invades the whole seed which grows out from the glumes as a hard, dark or purple spur-like process (_ergot_ stage), then falling on the ground it grows up as a minute stalk with rounded head containing spores. =Honey dew= growing on leguminous plants is reputed to cause skin disease in white horses and on the white spots of dark horses, from which those not eating the diseased plants escaped. _Bacterial ferments_ have an equally bad reputation. Bastin records the poisoning of five foals by fermented rye; Dieckerhoff describes an acute gastro-enteritis with congestion and swelling of liver, spleen and kidneys, as the result of microbes and their products in the fodders. Galtier traced a pneumoenteritis in the horse to two cocci, a motile _diplococcus_ and non-motile _streptococcus_. Both stained in aniline colors, and were bleached by iodine. They grew in ordinary culture media above 50° F. but most freely at 98° F. The animals were infected by drinking putrid water or spoiled fodders in which the microbes were contained. The change to boiled water in the former case led to their prompt disappearance. Reynal, Cailleux and Foucher have also adduced instances of severe enteritis in the horse from drinking putrid water. These animals showed active congestion of the intestinal mucosa with abundant infiltration of the submucosa. Bouley found 14 cases in one stable, the owner of which had marketed the good fodder and kept the spoiled for home use. Barthelemy, Alasonniere, Lombroso and Hausmann, Clichy, Rey, Gamgee and others give similar examples. A large number of observations show the dangerous results on the horse of mouldy bread, inducing colics, vertigo, profuse sweating. _Symptoms_. When =Adynamia= prevails there is great dullness and depression, the senses are blunted, the head depressed resting on the manger, the eyes sunken, weeping and half covered by the drooping upper lid, the conjunctiva is congested, sometimes yellow or marked by petechiæ. The mouth is hot, the lower lips pendent, the tongue furred, the abdomen somewhat tympanitic, with slight colics, but with little rumbling or indication of peristalsis. There is a primary constipation, a few small, hard pellets being passed with effort. The temperature may be 102° to 104°, breathing short, pulse small, weak; the walk unsteady, the animal preferring to stand, completely apathetic. In some cases a profuse diarrhœa sets in and may prove fatal.