The Motor Functions of the Intestine From a New Point of View

According to modern textbooks the small bowel is a tube whose structure and physiologic characteristics are much the same from one end to the other; and material is supposed to move aborally because of the myenteric reflex, or Bayliss and Starling's "law of the intestine."According to this law,1 "Excitation at any point of the gut excites contraction above and inhibi- tion below"; and it can easily be seen how this mechanism must favor the aboral progress of material through the intestine.Cannon2 has warned us, however, that this reflex and normal peristalsis are not the same, nor is it always in control of the mechanism of the bowel.A moment's thought will show that this must be true; otherwise food once introduced into the duodenum would never stop in its rush to the anus.My own graphic records of peristaltic rushes, secured with six or seven entero- graphs, rarely show any relaxation before the oncom- ing wave.On the contrary, powerful contractions appear below, which serve to stop the rush from going too far.Unfortunately, the stimuli ordinarily used to elicit the reflex have been traumas pinches, sudden dis- tention by balloons, etc., and little effort has been made to see what happens above and below the normal loop- ful of digesting food.3Much might be said about the difficulties met with by those who have studied this reflex; about the narrow limits (2 to 3 cm.on either side of the stimulus) within which it ordinarily is operable, but it would be beside the point.The exis¬ tence of the reflex has been well established ; but we do not know how far it enters into normal peristalsis, and we must admit that this explanation for the downward progress of food through the intestine is not sufficient in itself.Perhaps for this reason the "law of the intestine" has been of little help to the gastro-enterologist in the solution of his problems."It does not govern the rhythmic contractions of the small intestine, the rhythmic peristalsis and antiperi- stalsis of the colon, and probably not the rhythmic waves of the stomach. . . .For these activities the tonic contraction of the wall of the canal is all- important."