Periods of active contraction of the small intestines in hunger were observed in the duodenal fistula case of Busch. Boldyreff found that the intestines (presumably both the large and small intestine) exhibit rhythmic contractions during the periods of gastric hunger contractions. His evidence consisted of the sounds produced by the moving gas in the intestines and the appearance of the free end of the fistula of the small intestine, during the periods of strong rhythmical contractions of the empty stomach. More accurate methods of registration should be devised. We have observed in dogs with duodenal fistula evidences of contractions in the duodenum during hunger contractions of the stomach (expulsion of bubbles of gas, fluid, debris, etc.). There can be no doubt that BoldyrefTs observation is correct. In two dogs we introduced balloons both into the stomach and into the large intestine (descending and transverse colon). The large intestine showed some contractions, but these were not correlated with the periods of gastric hunger contractions, although the interesting theory recently developed by Alvarez seems to imply that increased tonus and contractions of the stomach must lead to increased motor activity in the entire gut below the stomach.
Rumbling intestinal sounds may be heard when the stomach is quiescent. These are probably due to local stimulation resulting from distension by the gases, hence mostly confined to the large intestine. Rumbling intestinal sounds are usually heard during gastric hunger periods, and it seems to us, one can at times actually feel the intestinal movements. If this is the case, the intestinal hunger movements must be much more vigorous than the digestive movements. The character of the intestinal hunger contractions is not known. Do they consist in peristalsis, in segmentation, or in pendulum movements? Or is it a type of contraction not seen during digestion: rhythmic contractions and relaxations throughout the whole intestine and synchronous with the systole and diastole of the hunger beats of the stomach and the lower end of the esophagus ? This would imply a type of co-ordination of the neuromuscular mechanism of the entire digestive tract not revealed by the movements of digestion. In the movements of digestion the esophagus, the cardia, the fundus, antrum pylori, the pyloric sphincter, and the intestines act as relatively independent mechanisms and appear to be governed by laws of their own in harmony with the r61e played by these regions in digestion.
While we admit the possibility that the contracting esophagus and intestines may contribute to the sensation of hunger, the proof for this is still wanting, and in any event the stomach is the main factor. The hunger pangs run absolutely parallel with the periods of gastric hunger contractions, only lagging some seconds both at the beginning and the end of each contraction. A strong contraction artificially induced in the empty stomach is recognized as a hunger pang; a similar contraction induced in the esophagus when the stomach is empty is recognized as something quite different from hunger. And this will in all probability prove to be true also of the intestines. No one can fail to recognize the difference between the sensations initiated by strong contractions in the small and large intestines and the rectum (intestinal cramp, tenesmus, defecation) and the gastric hunger pangs.