_Croupous Inflammation._ The mucous membrane is also subject to a chronic or sub-acute form of inflammation resulting in the production of an exudation much resembling that of croup. Sometimes it forms in a layer of some thickness, pretty uniformly over the surface, or appearing in the stools as tubular casts of the intestines; sometimes it is very thin, or consists of mere shreds. The anatomical changes observed will be similar to those just noticed. _Perityphlitis_ is an inflammation of the loose areolar tissue around the cœcum, occurring primarily or in consequence of typhlitis. If not checked, it ends in the formation of abscess in the right iliac fossa, which may discharge either into the neighboring viscera, or externally through the abdominal walls, mostly near Poupart’s ligament. _Peripractitis_ is an inflammation of the areolar tissue around the rectum. The resulting abscess discharges either externally, back of the anus, or in the perineal region, or internally into the rectum, or more rarely into the bladder, the vagina, the uterus, or into some other part of the intestines. Fistula in ano, frequently originates in this manner. =Ulceration.= Ulceration may occur as the result of inflammations both catarrhal and croupous, and whether commencing in the mucous or the muscular layer, the ulcers may perforate the intestinal walls and give rise to an escape of the contents; or the ulcers may cicatrize with the formation of the usual fibroid tissue, which, by subsequent contraction, may give rise to puckering or obstruction. _In follicular ulceration_ of the colon, after lientery or tedious diarrhœa, the follicles are at first tumefied, and project as smaller or larger, round, conical nodules on the internal surface of the intestine, surrounded by a dark red vascular halo. Ulceration takes place in their interior; an abscess with red, spongy walls appears; the follicle is eaten away, and an ulcer of the size of a pea or lentil is formed. The mucous membrane is extensively destroyed, and with great rapidity. The disease is always confined to the colon, but when it runs a very rapid course, it may be accompanied with catarrhal inflammation of the small intestines.