In 1894 Grützner published an observation and made an assumption about which there has since been much controversy. He maintained that when normal salt solution, holding in suspension hair, powdered charcoal, or starch grains, is injected into the rectum, it is carried upward into the small intestine and may even enter the stomach. These experiments have been repeated by several observers. Some have confirmed Grützner’s results; others have failed, after using most careful methods, to find any evidence of the passage of the injected material back to the stomach, and they have declared that the apparent success was due to carelessly allowing the food of the animal to become contaminated with the test materials, so that these were introduced into the stomach by way of the mouth. That antiperistalsis does not occur in the small intestine seems to be proved by Mall’s experiment of reversing a portion, sewing it in place, and then finding that the food does not pass the reversed region, but collects at the upper end. Sabbatani and Fasola reversed stretches of small intestine of varying length, and found that the reversed portions allowed fluids to pass, but that the persistence of the physiological direction of movement caused an accumulation of undigested food in the region of the upper suture. However a portion of the intestine lay in relation to the rest, it always manifested the normal peristalsis. Many other observers working directly on the intestine confirm this testimony and state that the progress of the constriction-rings is always downward, and that antiperistalsis is not physiological. In 1898, however, Grützner took his stand again in favour of a backward movement in the intestines, and in a somewhat metaphysical manner argued that peristalsis and antiperistalsis belong to each other just as relaxation of muscle is related to contraction. He assumed that as the contents are advanced by slow peristalsis, so are they returned by a similar movement in the opposite direction, and he mentions several pathological cases (fistula of intestine) to substantiate the assumption.