Among other factors in gastric digestion, the muscular movements of the stomach walls are to be emphasized, since we have here a mechanical aid to digestion of no small moment, and likewise a means of accomplishing the onward movement of the stomach contents. The outer walls of the stomach are composed of a thick layer of circular muscular fibres, especially conspicuous at the pyloric end of the organ, where the latter is joined on to the intestine; a smaller, less conspicuous layer of longitudinal muscle fibres, and some oblique fibres. At the pylorus, the circular fibres are so arranged as to form a structure which, aided by a peculiar folding of the inner mucous membrane, serves as a sphincter, closing off the stomach from the duodenum, the beginning of the small intestine. The movements of the stomach were first made the subject of careful investigation by Dr. Beaumont in his study of the celebrated case of Alexis St. Martin, a French Canadian, who, in 1822, was accidentally wounded by the discharge of a musket, with the resultant formation of a permanent fistulous opening in the stomach. Dr. Beaumont, in the description[7] of his observations, writes that “by the alternate contractions and relaxations of these bands (of muscle) a great variety of motion is induced on this organ (the stomach), sometimes transversely, and at other times longitudinally. These alternate contractions and relaxations, when affecting the transverse diameter, produce what are called _vermicular_ or _peristaltic_ motions.... When they all act together, the effect is to lessen the cavity of the stomach, and to press upon the contained aliment, if there be any in the stomach. These motions not only produce a constant disturbance, or _churning_ of the contents of this organ, but they compel them, at the same time, to revolve around the interior, from point to point, and from one extremity to the other.” Of more recent investigations, the most important are those made by Cannon,[8] with the X-ray apparatus. From these later studies, it is evident that Dr. Beaumont’s view of the entire stomach being involved in a general rotary movement is not correct, since in reality the movements are confined mainly to the pyloric end of the stomach, the fundus or portion nearer the œsophagus not being directly involved. This means that when food material passes into the stomach, it may remain at the fundic end for some time more or less undisturbed before admixture with the gastric juice occurs, and under such conditions, until acidity creeps in, the salivary digestion of starch can continue. [7] The Physiology of Digestion. By William Beaumont, M.D. Second Edition, 1847, p. 100. [8] W. B. Cannon: The Movements of the Stomach studied by means of the Röntgen Rays. American Journal of Physiology, vol. 1, p. 359.