There remain to be considered, as a possible cause of hunger pangs, contractions of the stomach and other parts of the alimentary canal. This suggestion is not new. Sixty-nine years ago Weber[195] declared his belief that “strong contraction of the muscle fibres of the wholly empty stomach, whereby its cavity disappears, makes a part of the sensation which we call hunger.” Vierordt[196] drew the same inference twenty-five years later (in 1871), and since then Ewald, Knapp, and Hertz have declared their adherence to this view. These writers have not brought forward any direct evidence for their conclusion, though Hertz has cited Boldireff’s observations on fasting dogs as probably accounting for what he terms “the gastric constituent of the sensation.” The Empty Stomach and Intestine Contract The argument commonly used against the gastric contraction theory is that the stomach is not energetically active when empty. Thus Schiff[197] stated, “The movements of the empty stomach are rare and much less energetic than during digestion.” Luciani[198] expressed his disbelief by asserting that gastric movements are much more active during gastric digestion than at other times, and cease almost entirely when the stomach has discharged its contents. And Valenti[199] stated (1910), “We know very well that gastric movements are exaggerated while digestion is proceeding in the stomach, but when the organ is empty they are more rare and much less pronounced,” and, therefore, they cannot account for hunger. Evidence opposed to these suppositions has been in existence for many years. In 1899 Bettmann[200] called attention to the contracted condition of the stomach after several days’ fast. In 1902 Wolff[201] reported that after forty-eight hours without food the stomach of the cat may be so small as to look like a slightly enlarged duodenum. In a similar circumstance I have noticed the same extraordinary smallness of the organ, especially in the pyloric half. The anatomist His[202] also recorded his observation of the phenomenon. In 1905 Boldireff[203] demonstrated that the whole gastro-intestinal tract has a periodic activity while not digesting. Each period of activity lasts from twenty to thirty minutes, and is characterized in the stomach by rhythmic contractions ten to twenty in number. These contractions, Boldireff reports, may be stronger than during digestion, and his published records clearly support this statement. The intervals of repose between periodic recurrences of the contractions lasted from one and a half to two and a half hours. Especially noteworthy is Boldireff’s observation that if fasting is continued for two or three days, the groups of contractions appear at gradually longer intervals and last for gradually shorter periods, and thereupon, as the gastric glands begin continuous secretion, all movements cease. Observations Suggesting that Contractions Cause Hunger