5. The food in the fundus is not moved by peristalsis, and consequently it is not mixed with the gastric juice; salivary digestion can therefore be carried on in this region for a considerable period without being stopped by the acid gastric juice. 6. The pylorus does not open at the approach of every wave, but only at irregular intervals. The arrival of a hard morsel causes the sphincter to open less frequently than normally, thus materially interfering with the passage of the already liquefied food. 7. Solid food remains in the antrum to be rubbed by the constrictions until triturated, or to be softened by the gastric juice, or later it may be forced into the intestine in the solid state. 8. The constriction-waves have, therefore, three functions: the mixing, trituration, and expulsion of the food. 9. At the beginning of vomiting, the gastric cavity is separated into two parts by a constriction at the entrance to the antrum; the cardiac portion is relaxed, and the spasmodic contractions of the abdominal muscles force the food through the opened cardia into the œsophagus. 10. The stomach movements are inhibited whenever the cat shows signs of anxiety, rage, or distress. THE MOVEMENTS OF THE INTESTINES STUDIED BY MEANS OF THE RÖNTGEN RAYS[33] BY W. B. CANNON _From the Laboratory of Physiology in the Harvard Medical School_ Extracts from _American Journal of Physiology_, 1902 INTRODUCTION The investigation of intestinal movements has been beset by the same difficulties that characterised the investigation of the gastric mechanism. Pathological subjects or animals subjected to the disturbing action of drugs and anæsthetics and of serious operations have been the only sources of our knowledge. A considerable difference of opinion as to the nature of the normal movements in the intestines has resulted from observations made under these necessary abnormal conditions. The slowly advancing peristaltic wave and the _Pendelbewegung_, or swaying movement, described by Ludwig, have been regarded as true physiological processes. Concerning antiperistalsis and the swiftly running vermicular contraction, observers are not so nearly in agreement. The activity of the large intestine has been described as simply peristalsis of a slower rate than that seen in the small intestine.