< Page:Popular Science Monthly Volume 74.djvu
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THE PHYSIOLOGY OF DIGESTION

177

matter," by citing the ease of the West Indies negroes who grow fat on sugar at certain seasons when they are at work on the cane. The absorption and need of water and "calcareous earth" is also discussed. The author reaches the conclusion that water not alone supplies the waste of fluids, but also goes to form the solids of the body. He says:

Dr. Fordyce informs us he put a gold-fish in a glass vessel, and supplied it with spring water; the fish lived in this manner for fifteen months, grew to more than double the size it was when first confined, and threw out much feculent matter. Lest it should be supposed the fish lived on substances held in the water by solution, he used distilled water and impregnated it with the air of the atmosphere, and put other gold-fish in the water thus treated, and kept them six months,[1] during which time they threw out feculent matter, and thrived as before mentioned.

In referring to the "action of the mind" on the secretion of saliva Young makes the following comment in a foot-note:

Is not the secretion of the saliva and gastric juice synchronous? It is highly probable from long habit, the actions of these two sets of vessels become associated; hence, when the stomach and its vessels are irritated, as in nausea, there is always a flow of saliva, though nothing stimulating has been applied to the mouth. The excitement of the vessels of the one seems to keep pace with that of the other; when the nausea is so great that vomiting is just at hand, the flow of the saliva is proportionally increased; and when we make an unsuccessful effort to vomit, we generally throw out a mouthful of saliva.

Is it far-fetched to recall in this connection the comparable psychic secretion which has been described in recent years for both saliva and gastric juice and the probability of a common stimulus for the production of each?

Let us now consider more particularly Dr. Young's observations on the processes in the stomach. He assumes that sufficient evidence was already at hand from experiments on animals to permit plausible, if not conclusive, inferences concerning our own digestion. He writes:

It would be unnecessary to recite particular experiments, to prove the solvent property of the gastric fluid, this being admitted on all hands. . . . The effects of solution are most remarkable in such animals as swallow their food without mastication; we will, therefore, relate a few experiments made on some of these.

Our common large bull-frog (Rana ocellata) was chosen in order to observe the effects of the gastric fluid, as they swallow all their prey whole. They have a large membranous stomach, which when distended, occupies the whole anterior part of the abdomen: the œsophagus is very wide, so that their food can be examined at pleasure. Two of a very large size were procured, and their stomachs were found to be greatly distended with food: being desirous of seeing what was their natural aliment, and the effects of their digestive power upon it, by means of a pair of forceps, one of their stomachs was easily emptied of its contents; and to my surprise, and that of others who witnessed the fact, it was found to contain a common sized spring frog, and afforded a fine oppor-

  1. ↑ One is reminded of J. Loeb's demonstration nearly a hundred years later that certain fishes can be put into distilled water without the least injury.
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