Consider this tube, for it is really unique. Note the longitudinal muscular bands (Figs. 12 and 13). We find this tube to be five feet long when the surface made by the circular bands is measured, and four feet long when that made by the longitudinal bands is measured. Now, the four feet of surface must of course contract the five feet. Well, in the tube under consideration, the musculo-areolo mucous tube is thrown into circular puckerings in short sections, between which are deep transverse creases, each bounded by prominent bulges. (Fig. 13.) An inspection of the bore of the tube shows a sharp ridge corresponding to each depression of the outer surface, and a large recess collocated with each external protrusion. This external and internal appearance of the large intestine reminds one somewhat of the flexible hard-rubber tubing used as a conduit for electric wire in houses. [Illustration: Fig. 11. Cavity of the cæcum, its front wall having been cut away. The ileocæcal valve and the opening of the appendix are shown. (Gerrish.)] [Illustration: Fig. 12. A view of the position and curvatures of the large intestine. 32, end of the ileum; 31, appendix vermiformis; 4, cæcum; 3, ascending, 2, transverse, 8, descending colon; 9, 9, 9, sigmoid flexure; 10, 10, rectum; 12, anus; 13, 13, bladder; 11, 11, 11, peritoneum--length from 4 to 6 feet, and a mean diameter of about 1-2/3 to 2-2/3 inches. The sigmoid flexure is a receptacle for the feces, and each end is the highest and bent on itself; this arrangement spares the rectum and sphincters of pressure and weight until the proper time to stool.] The sacculated pouches thus formed by the shortening of the bowel may become abnormally distended, and resemble the proper receptacle for feces--the sigmoid flexure. Even the rectum, in cases of chronic constipation, is usually enormously distended, owing to the overloading or filling up of the bowel with feces. I have given this somewhat lengthy _résumé_ in order to enable the reader to appreciate a most pertinent question. Let us see what we have found: The small intestine, with its manifold folds and its numerous pockets, made by the forty feet of mucous membrane; the bends and curves in the five feet of the large intestine, with its numerous dams and pools; and, lastly, the abnormal reservoirs for feces, liquids, and gases. [Illustration: Fig. 13. Segment of large intestine, showing the characteristic features of its structure. (Gerrish.)]