During the embryonic development of the human intestine wide change in position takes place before the adult arrangement is obtained. This change in position is designated as rotation. The exact reason for rotation is not known; in fact, embryologic investigations, which consisted of the study of developing embryos 5 mm. or more in length, have indicated that no physiologic reasons are known. Rotation is secondary to the herniation of the midgut into the umbilical cord and apparently is the result of the physical forces inside and outside the hernial sac and of the differences between the physical properties of the small intestine and those of the large intestine at the time they are "sucked back" into the abdomen.
If a patient whose intestine has failed to rotate regularly presents certain digestive difficulties, the nature of these disturbances should indicate the physiologic function which results from the special anatomic arrangement produced