virtually on a straight line, is seen clearly. The strip at the bottom shows, in addition to the clear-cut separation of the fractions, the relative lack of lateral diffusion and absence of tailing.Simple visual examination of the results obtained with the new technique revealed several differences from patterns obtained with the Spinco Durrum apparatus. With the new apparatus, for instance, a distinct prealbumin band was characteristically present in all serum samples (Figure 1). The alpha 1 and alpha 2 proteins were more clearly separated, and the relative proportions of all fractions shown by the microelectrophoretic procedure were somewhat different from those shown by the Durrum apparatus.Efforts have been initiated to place the analysis of the patterns on a quantitative basis by adapting the Spinco Analytrol for use with the cellulose acetate membranes. By proper masking, one can even analyze each narrow strip without detaching it from the original membrane. The densitometric analysis of a broad strip shown in Figure 2 reveals that each peak was extraordinaria sharp. The pen did not return to the base line between peaks only because the slit width was not narrow enough to prevent overlap. Work is under way to correct this problem of slit width as well as to select the proper filter combination. Other analyzing and integrating systems are also under examination. DISCUSSIONWe are in perfect agreement with Kohn (3) regarding the high quality of cellulose acetate as a supporting medium for electrophoresis. In all instances the separation of serum proteins is free of tailing and overlap of bands, resulting in separations which are superior to those achieved with filter paper. When used with the apparatus described herein, several additional advantages accrue.The first is that a supporting "sandwich" of glass for the membrane is not needed. The second is speed, for at the present time the entire process of separation, staining, and analysis with integration of four separate serum samples has been completed in about 1 hour. (This period of separation was shortened by diluting the buffer to 0.05 ionic strength and doubling the usual voltage to 200 volts without exceeding 1 ma. in current.) A third advantage is that identical samples of serum may be run simultane-ously, side by side, on parallel portions of the same strip, then stained separately to reveal a variety of different molecular species and to achieve a truly comprehensive analysis of a given sample. The technique is now being used with great success for the separation of nucleotides, inks, dyes, and other biological materials such as dried blood.