_Lesions._ In the first reported cases in calves in 1877 (Proger and Zurn), there was catarrhal inflammation of the upper air passages as well as the bowels. There was thickening, redness and desquamation of the abomasum near the pylorus of the small intestine and colon. In the intestines there were patches of thickening and softening of the mucosa and miliary ulcers with yellowish contents. The mesenteric glands, liver and spleen were enlarged, softened and ecchymosed. In all the lesions coccidia were found. In the cases reported by Hess, Zschokke, Guillebeau and Cadeac the abomasum and large intestine principally suffered. There was a diffuse inflammation of the mucosa and in the rectum and portion of the colon a great degeneration and desquamation of the epithelium. The columnar cells of the mucous glands especially suffered. A single cell would contain five or six psorosperms, in different stages of development. If the parasites have escaped, the cell walls are pressed together. Among the diseased glands others with healthy epithelium were found, their orifices plugged with mucus. Both forms of coccidia above described are found in two conditions, in the epithelial cells with granular nuclei staining in hæmatoxylon, and violet or black with iodine (Lugol’s), and outside the cells with granular nucleus or simple hyaline contents which do not stain. Zschokke considers the latter as in process of degeneration. Other organs are anæmic. _Symptoms._ The disease is ushered in by cold extremities, weakness, dullness, suspended rumination, ardent thirst, hyperthermia, 102° to 104° and even 106°, small, weak thready pulse beating 100 to 140 per minute, sunken eyes, grinding of the teeth, and defecation in small quantity only. Toward the fourth day or earlier a fœtid diarrhœa sets in, watery, bloody and fibrinous. The bloody discharges last to the seventh day, the diarrhœa to the end of the second or fourth week. Straining may be violent, exposing or everting the irritated or ulcerated rectum, the hind parts may be stiff, the patient rises with difficulty, he winches if pressed on the back or right side of the abdomen, loses flesh rapidly and becomes a walking skeleton. when the discharges are less profuse cylindroid croupous casts are sometimes expelled. _Course._ _Duration._ In the weak and young a violent attack may prove fatal in 24 hours. In others the malady lasts for two or more weeks and sometimes relapses, and the patient becomes very weak and anæmic. Complications of various kinds may also supervene and cut off the animal, the lesions and debility alike favoring the introduction of the germ. Thus black quarter, bronchitis, pneumonia, convulsions, paralysis, phthiriasis and ring-worm have been noted as sequelæ. _Diagnosis_ can always be made by microscopic examination of the fresh warm fæces. _Prevention._ This will consist in the avoidance of water and of green food from soils where the disease has been found to prevail.