The swift vermicular wave may pass the whole length of the intestine in about a minute. It is often seen just after death, as well as in pathological states such as intestinal anæmia or hyperæmia, and when the bowel contains gases and organic acids from decomposing food. Starling is inclined to regard this type of intestinal activity as an exaggeration of the rhythmic type; Mall, on the other hand, places it in a class by itself, and declares that its service is to rid the intestine rapidly of irritating substances. Nothnagel, who designates this form of movement with the term _Rollbewegung_, thinks it is transitional between a physiological and a pathological activity. The existence of antiperistalsis has been so much questioned that it will be considered in a special section of this paper, where my observations may be conveniently introduced. The common understanding of the manner in which food passes through the intestinal canal is that the chyme ejected from the stomach is pressed downward by a peristalsis, which passes slowly over a part or all of the small intestine. The peristaltic waves of the colon are supposed to constitute an independent group, similar to those of the small intestine, but weaker and slower. Movements of the food other than the uninterrupted advance have been mentioned by some observers. Starling states that the effect of the pendulum movement is to mix the contents of the intestine and bring them into intimate contact with the mucous membrane. Grützner writes that he has been brought “by strange and peculiar observations” to believe that the fluid contents of the small intestine move irregularly forward, then forward and back, then perhaps remain quiet for some time, only to pass backward for a long distance, and finally to move forward steadily to the end. In this manner the food is mixed and brought into contact with the absorbing walls. The to-and-fro shiftings of the food Grützner ascribed to advancing and retrograde contractions of the intestinal musculature, and he argued that even circular constrictions must force the liquid contents away in both directions. To support his contention, Grützner introduced mercury into the intestine and observed it with the Röntgen rays. After noting a backward and forward movement of the mercury he dismissed the method, saying, “Many a flash must come from the Röntgen tube before the _normal_ movement of the intestinal contents is made entirely clear by this method.” The following account is a summary of many repeated observations on different animals, and is a contribution to a clear understanding of the normal movements of the intestines and their contents. THE MOVEMENTS OF THE SMALL INTESTINE