Movement of the contents of the alimentary canal may be favoured by judicious pressure, or massage. From the description of the situation of its several parts given above, it will be understood that if the right hand be placed on the abdomen immediately beneath the ribs, with the fingers well round to the left side, the stomach will be covered. Pressure from left to right will tend to drive its contents towards the pyloric valve. The small intestine is so irregular in its course as to preclude the possibility of following it with the hand. Pressure first on one side and then on the other, with a general tendency to work from above downwards, tends to press forward its contents; but, owing to its circular form and strong muscular walls, it is not in much need of help. Very different is the position of the large intestine in this respect. Its calibre is much greater, its wall is sacculated, its contents comparatively firm. If the palm of the hand be placed above the right groin and pressure directed upwards, the cæcum coli and ascending colon are emptied. If pressure be directed from the extreme right side just below the ribs, across the middle line to the left side, the transverse colon is emptied. The descending colon needs pressure from above downwards on the left side; the sigmoid flexure, pressure above the left groin, downwards, and towards the middle line. The inner wall of the œsophagus is smooth, save for the wrinkles into which it is thrown when not distended; but from the cardiac orifice of the stomach onwards the mucous membrane of the alimentary canal exhibits folds and other projections which serve many purposes. They serve to delay the food, keeping it longer in contact with the secreting surface. They increase the area pitted with tubular glands; they increase also the area through which absorption of the products of digestion occurs. On the inner surface of the stomach the folds produce a reticulated pattern. In the upper portion of the small intestine, especially the duodenum, there are prominent transverse shelves (valvulæ conniventes). No definite folds occur below the upper three-fourths of the small intestine, with the exception of the constrictions of the transverse colon already referred to, which affect the whole thickness of its wall. Throughout the whole of the small intestine the mucous membrane projects in finger-like processes, or villi, which give it a characteristic velvety appearance. The villi are longest in the duodenum. Lymph-follicles occur at intervals in the intestine. In the ileum they are collected into patches (Peyer’s patches), on the side opposite to the line of attachment of the mesentery. They serve both for the supply of phagocytes, which hunt any germs that have penetrated the mucous membrane, and also as stations to which germ-laden phagocytes retreat.