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500 subsequently to slough away. Sores so formed are necessarily ragged and irregular in outline, and may even surround pieces of comparatively healthy mucous membrane. The floor of the active dysenteric ulcer may be, and generally is, formed of a sloughy material lying on the muscular coat; but the sore may penetrate deeper than this, and include the muscular coat itself, and even the serous membrane. The largest ulcers are generally found in the sigmoid flexure and descending colon; they are also frequently, though more rarely, found in the cæcum, the magnitude of the lesions diminishing as we trace the bowel upwards or downwards, as the case may be.

Along with the ulceration there is intense congestion of the non-ulcerated parts of the mucous membrane. In places there may be œdema of the submucosa; there may be small abscesses which elevate the mucous membrane; and there may also be distension of the solitary follicles by a mucoid or purulent material. In some instances a large portion of the mucous membrane may be seen to have died en masse and become gangrenous. In such, extensive sloughs may be thrown off as a sort of tube, apt to be mistaken during the lifetime of the patient for a diphtheritic cast of the bowel. Fulminating dysentery.— Strong and Musgrave thus describe the lesions in this type of dysentery as it occurs in the Philippine Islands:— "In the most acute cases (death after three or four days' illness) the mucous membrane of the large intestine presents in general a reddened, swollen, puffy appearance. There is a superficial necrotic mucous layer which generally extends over the mucosa throughout the large bowel, and sometimes for a distance of 10 or 12 cm. into the ileum. This necrotic layer consists of mucus, red blood-corpuscles, leucocytes, epithelial cells, with many large swollen granular cells, and bacteria ; no amoebae are found. If one brushes the mucous layer lightly aside with the finger the bright- red injected appearance of the intestinal wall becomes more plainly visible. Dotted here and there throughout are small, diffuse, bright-