The constancy of various physiologic activities and the chemical uniformity of some of the body fluids under certain well defined conditions have been of considerable value to the practice of medicine. Thus the rate of the heart beat, when properly controlled, may become an index of normal function; variations in the composition of the blood from a certain fixity that is characteristic of health may betray the presence of pathologic conditions. The heat regulation of the organism ordinarily prevents more than small deviations of the body temperature from a well established "normal." The progress of clinical biochemistry has made it possible to measure the gastric functions by quantitative methods, and has awakened enthusiastic hopes of the value that the data secured will contribute to the diagnosis of alimentary abnormalities.
There are recurring indications that some of the earlier assumptions regarding the gastric juice may have been unduly rigorous. There was