It is recognized that the constituents of the blood are of as great a clinical significance as the constituents of the products of excretion, but heretofore blood analysis has not been undertaken as a matter of routine in the clinic, on account of the technical difficulties in the methods employed or because of the large amounts of blood required. Folin and Denis,1 however, have recently described relatively simple and accurate ways for estimating the non-protein nitrogen, urea, ammonia, and uric acid of the blood, and Marshall2 has published a method for determining blood urea. These various tests are proving of great value, because clinicians are now able to estimate the nitrogen containing elements of blood as part of the ordinary study of different types of disease.
Since Claude Bernard3 recognized that glucose could be found in the circulating blood, a large literature on blood-sugar has accumulated. Two