appears to be designed to prevent the aliments from arriving at the pylorus. We perceive also irregular contractions, beginning at the duodenum, and extending to the pyloric portion of the stomach, the effect of which is to push back the aliments towards the splenic part. The aliments remain in the stomach long enough to undergo no other modifications than those which result from their mixture with the perspiratory and mucous fluids, which are constantly found in it and renewed there. During this time the stomach remains uniformly distended; but afterwards the pyloric portion contracts in its whole extent, especially in the part nearest the splenic portion, towards which the aliments are carried. Then there is found, in the pyloric portion, only the chyle mixed with some unchanged aliments. When there is accumulated in this part a quantity of it, which is never very considerable, there is seen, after a moment of rest, a contraction at the extremity of the duodenum; the pylorus and the pyloric portion soon take part in this motion, and the chyle is forced towards the splenic portion; but afterwards the motion is in an inverse direction. The pyloric portion, which allowed itself to be distended, contracts from left to right, and directs the chyle towards the duodenum, which soon passes the pylorus and enters the intestine. The same phenomenon is repeated a certain number of times, then it ceases, and commences again after some time. This motion, when the stomach contains much food, is limited to that part of the organ nearest the pylorus; but as it becomes empty, the motion extends, and appears even in the splenic portion when the stomach is almost entirely evacuated. In general, it becomes more evident at the end of chylification. The motion which produces the progression of the chyle in the small intestines is very analogous to that of the pylorus; it is irregular, made at variable intervals, it is sometimes in one direction and sometimes in another, and sometimes appears in many parts at once; it is always more or less slow, it produces changes of relations in the intestinal circumvolutions, and it is entirely beyond the influence of the will. We should form a very false idea of the motions of the small intestines during digestion, if we judged of them by those which these intestines exhibit in an animal recently killed. In this case, it is not the annular fibres only that enter into action, so as to exhibit, by their successive contractions, a vermicular motion. The longitudinal fibres act also in a very conspicuous manner, and produce a rolling of the intestinal circumvolutions, which change their relations at every instant. These motions are never more evident than when the whole mass of intestines is removed from a living animal.