but to related skin areas. Under such circumstances we do not dismiss the testimony as worthless merely because it may not point precisely to the source of the trouble. On the contrary, we use such testimony constantly as a basis for judging internal disorders.
With regard to the contention that reference to the periphery is not proof of the peripheral origin of a sensation, we may answer that the force of that contention depends on the amount of accessory evidence which is available. Thus if we see an object come into contact with a finger, we are justified in assuming that the simultaneous sensation of touch which we refer to that finger has resulted from the contact, and is not a purely central experience accidentally attributed to an outlying member. Similarly in the case of hunger—all that we need as support for the peripheral reference of the sensation is proof that conditions occur there, simultaneously with hunger pangs, which might reasonably be regarded as giving rise to those pangs.
Objections to Some Theories that Hunger is of Local Origin
With the requirement in mind that peripheral conditions be adequate, let us examine the state of the fasting stomach to see whether indeed conditions may be present in times of hunger which would sustain the theory that hunger has a local outlying source.
Hunger not Due to Emptiness of the Stomach.—Among the suggestions which have been offered to account for a peripheral origin of the sensation is that of attributing it to emptiness of the stomach. By use of the stomach tube Nicolai found that when his subjects had their first intimation of hunger the stomach was quite empty. But, in other instances, after lavage of the stomach, the sensation did not appear for intervals varying between one and a half and three and a half hours. During these intervals the stomach must have been empty, and yet no sensation was experienced. The same testimony was given long before by Beaumont, who, from his observations on Alexis St. Martin, declared that hunger arises some time after the stomach is normally evacuated. Mere emptiness of the organ, therefore, does not explain the phenomenon.
Hunger not Due to Hydrochloric Acid in the Empty Stomach.—A second theory, apparently suggested by observations on cases of hyperacidity, is that the ache or pang is due to hydrochloric acid secreted into the stomach while empty. Again the facts are hostile. Nicolai reported that the gastric wash-water from his hungry subjects was neutral or only slightly acid. This testimony confirms Beaumont's
- Head, Brain, 1893, XVI., p. 1; 1901, XXIV., p. 345.
- Nicolai, "Ueber die Entstehung des Hungergefühls," Inaugural-Dissertation, Berlin, 1892, p. 17.
- Beaumont, "The Physiology of Digestion," second edition, Burlington, 1847, p. 51.
- Nicolai, loc. cit., p. 15.