Research in blood chemistry and its clinical application has been almost entirely an American achievement. When it is recalled that this whole subject is now only in its infancy, the widespread use of blood chemical analyses is quite remarkable. Ten years ago accurate clinical methods for the determination of blood urea, uric acid, and creatinin were practically unknown. Closely following the invention of suitable technical procedure, many conclusions have been stated and reiterated as to the significance of high blood concentration of these substances. Some of them are based on slow, painstaking scientific work; others are largely the result of ingenious surmises supported by cases selected to prove the point. This paper deals with the interpretation of high uric acid figures in the blood. Before 1912 there had been practically no work on this theme. The fact that in gout there was an excess of uric acid in the blood,