_Lesions._ The carcasses putrefy with extraordinary rapidity being as a rule pervaded by septic microbes and their toxins. The blood is of a deep red, loosely and imperfectly coagulated, and accumulated in the veins and subcutaneous connective tissue. The large intestines are the special seat of the disease, the walls being found hyperæmic, with concentration especially on the mucous surface which is red, congested, infiltrated, tumefied so that it is easily detached under pressure by the finger, or broken down into a putrid pulp. At other points the epithelium or the whole mucosa has been detached leaving ulcers, varying from mere erosions to the deep and even perforating sores, through which the putrid contents escape into the abdominal cavity. At other points the surface is covered by necrotic masses surrounded by a swollen margin of living mucosa. Elsewhere the eschars have been detached and the granulating base and margin have contracted into more or less perfect cicatrices. The contents of the affected bowel may be largely mucopurulent, or it may be mixed with blood, with eschars and putrilage from the sores and at times with small packed masses of food, but in all cases it is very putrid and repulsive. It always contains the elements of blood and exudation, together with many microbes, the predominance of individual species suggesting the main factors in the pathogenesis. Peyers’ patches and the solitary glands are often the seat of infiltration and ulceration. Virchow points out that in man the lesions are largely concentrated in the flexures of the colon in which the ingesta is longer delayed, and the very convoluted arrangement of the viscus in cattle may be one reason of their special predisposition to the disease. The small intestines are exceptionally implicated, and the abomasum red, congested, ecchymosed and even ulcerated. The mouth and pharynx are often congested, with erosions and ulcerations on the gums and tongue. The mesenteric glands are red and swollen or pigmented of a dark gray color, and these or the adjacent connective tissue may be the seat of abscess. The liver is enlarged congested, of a yellowish red color, with granular degeneration and softening. Hepatic abscess is rare in cattle. The spleen is engorged with black blood and distinctly enlarged. _Diagnosis._ Dysentery is distinguished from rinderpest by the slower advance of the hyperthermia, by the absence of buccal concretions of epithelium, and of vaginal congestion, and above all by the absence of the virulent contagion by which the rinderpest spreads widely and rapidly, irrespective of special unwholesome environment. The lesions of dysentery are concentrated on the large intestines, while in rinderpest they are extended over the whole alimentary canal, and do not spare other mucosæ.