Methods for fractionation and analysis of proteins are developed and applied to the purification of specific proteins for the study of their function and structure. Displacement chromatography is being developed for the fractionation of macromolecules and particles of biological interest, employing polyanions and polycations differing in molecular size and charge density as displacers. Current efforts are directed toward the isolation of proteins from the granules of guinea pig neutrophils for use as markers in studies on the regulation of the maturation of these cells.