The origin of the albumin in the urine is intimately concerned with the fundamental metabolic disturbances of nephritis. Immunologic studies of these proteins have thus far proved almost totally unproductive on account of the fact that serum proteins are usually present in albuminurias, and the separation of this blood serum fraction has thus far proved impossible.
Aside from the Bence-Jones protein which is probably not concerned in the problem of nephritis, pure urinary proteins have only been prepared in a few isolated cases in which crystallization took place. Such cases have been reported by Paten,1 Bayne-Jones2 and Hektoen, Kretschmer and Welker,3 and a large series of cases by Welker, Thomas and Hektoen.4 Excretion of protein-containing urine free from blood proteins has never been reported. In the cases quoted, the workers were unable to extract any proteins from tissues which reacted with antiserums prepared for the urinary proteins. The surest method