What is the explanation of the orderly progress of the food residues along the alimentary tract? It is evidently dependent on a well regulated mechanism that provides for a downward movement from the stomach to the colon. According to the "law of the intestine" that is currently taught, a stimulus, such as is represented by the presence of a bolus of food, applied to any part of the intestine normally provokes a contraction above and a relaxation below the place of application. The result of this is a forward movement by propulsion of the food mass.
The phenomenon just outlined appears to be associated with a suitable reflex—the myenteric reflex, as it has been termed—which forms the basis for the control and proper sequence of the progressive peristalsis. A difficulty in accepting such an interpretation has arisen, however, because of the apparent lack of any nervous arc over which the