Recent reports by Aldrich,1 who made tests by intradermal injections of physiologic solution of sodium chloride, showed clearly that edema was due to an increased hydrophilic action of the tissue colloids and not simply to renal obstruction. With this point in view, the following method was devised to study the colloid affinities of the proteins in the blood.
The apparatus used was a glass tube with a bell-shaped end. The bell end was closed with a collodion membrane, and the tube was filled with serum with a fine bacteriologic pipet. The tube was so graduated that when filled to a certain point it would read in percentage of swelling of the original volume of serum, as is shown in the illustration.The ends of these tubes were then immersed in hundredth-normal hydrochloric acid, and the percentage of swelling was noted.Dialysis of the same serum against water, physiologic