Page:Popular Science Monthly Volume 74.djvu/178



Y interest has lately been aroused in reading a little American monograph published over a hundred years ago as a dissertation submitted for the degree of doctor of medicine to the faculty of the University of Pennsylvania. It is entitled: "An Experimental Inquiry into the Principles of Nutrition and the Digestive Processes," by John P. Young, of Maryland (submitted June 8, 1803). The essay does not appear to have received notice from the writers of that period; nor was there, probably, more occasion for calling attention to this monograph than to the usual doctor's thesis of the present day. Dr. Young's contribution, nevertheless, seems noteworthy because, in examining the knowledge of digestion then current, he applies the test of experimental evidence obtained at first hand—a sort of critique less in vogue in his day than in ours. On the title page he quotes from Lavoisier: "We ought in every instance to submit our reasoning to the test of Experiment, and never to search for truth, but by the natural road of Experiment and Observation." The dissertation further possesses a value, aside from its intrinsic merit as a scientific inquiry, in giving some indication of the status of physiological studies in America at the opening of the nineteenth century and in the first medical college of this country. To appreciate Dr. Young's monograph in the light of those times one must indulge in a moment's retrospect.

The history of the physiology of digestion may conveniently be divided into three periods. The first of these embraces the earlier days of science until the publication of Haller's "Elementa Physiologise" (1757), when theory and debate still maintained the triumph of the "animal spirits" and the various conceptions of "vital principles." In the succeeding epoch Réaumur (1752), Stevens (1777) and Spallanzani (1783) put into practise the teaching of Bacon: