The observations recorded in this paper have, as already noted, numerous points of similarity to Boldireff’s observations[40] on the periodic activity of the alimentary canal in fasting dogs. Each period of activity, he found, comprised not only widespread contractions of the digestive canal, but also the pouring out of bile, and of pancreatic and intestinal juices rich in ferments. Gastric juice was not secreted at these times; when it was secreted and reached the intestine, the periodic activity ceased. What is the significance of this extensive disturbance? I have elsewhere presented evidence[41] that gastric peristalsis is dependent on the stretching of gastric muscle when tonically contracted. The evidence that the stomach is in fact strongly contracted in hunger—i. e., in a state of high tonus—has been presented above.[*] Thus the very condition which causes hunger and leads to the taking of food is the condition, when the swallowed food stretches the shortened muscles, for immediate starting of gastric peristalsis. In this connection the observations of Haudek and Stigler[42] are probably significant. They found that the stomach discharges its contents more rapidly if food is eaten in hunger than if not so eaten. Hunger, in other words, is normally the signal that the stomach is contracted for action; the unpleasantness of hunger leads to eating; eating starts gastric digestion, and abolishes the sensation. Meanwhile the pancreatic and intestinal juices, as well as bile, have been prepared in the duodenum to receive the oncoming chyme. The periodic activity of the alimentary canal in fasting, therefore, is not solely the source of hunger pangs, but is at the same time an exhibition in the digestive organs of readiness for prompt attack on the food swallowed by the hungry animal.
[*] The “empty” stomach and esophagus contain gas (see Hertz: Quarterly Journal of Medicine, 1910, iii, p. 378; Mikulicz: Mittheilungen aus den Grenzgebieten der Medicin und Chirurgie, 1903, xii, p. 596). They would naturally manifest rhythmic contractions on shortening tonically on their content.
REFERENCES
[1] Cannon: The Mechanical Factors of Digestion, London and New York, 1911, p. 204.
[2] Bardier: Richet’s Dictionnaire de Physiologie, article Faim, 1904, vi, p. 1. See, also, Howell: Text-book of Physiology, fourth edition, Philadelphia and London, 1911, p. 285.
[3] See Sternberg: Zentralblatt für Physiologie, 1909, xxii, p. 653. Similar views were expressed by Bayle in a thesis presented to the Faculty of Medicine in Paris in 1816.
[4] See Hertz: The Sensibility of the Alimentary Canal, London, 1911, p. 38.
[5] Schiff: Physiologie de la Digestion, Florence and Turin, 1867, p. 40.
[6] Luciani: Das Hungern, Hamburg and Leipzig, 1890, p. 113.
[7] Tigerstedt: Nagel’s Handbuch der Physiologie, Berlin, 1909, i, p. 376.