-j- cellular debris and a cytoplasmic stripping agent (cetrimid) to release - intact nuclei. The nuclei were counted and sized with a Coulter electronic counter (Model A). Previous experiments (Conard, 1969) had shown that the transformed cells had nuclei which were larger than 47 cubic microns, The percent transformation was obtained by comparing the number of larger cells with the total number of cells present. With the above culture technique, the leukocytes removed from the buffy coat are predominantly lymphocytes, but with varying fractions of other leukocyte’s, principally neutrophils. _ Although the total number of cells was constant at the beginning of culture for each individual, the number of lymphocytes varied because of slight differences in differential counts. However, by 72 hr, when the final counts were done, practically all neutroshils had disappeared from the cultures so that the percentage transformation of lymphocytes was not Significantly affected by this variable. Serum proteins. - Serum was collected from non-heparinized aliquots of blood from each individual. Total serum proteins (g/100 ml) were determined with a refractometer (American Optical-TS). Separation of serum proteins into albumen and alpha-1, alpha-2, beta, and gamma globulin fractions was done by microelectrophoresis with strips of cellulose acetate (Phoroslides) and a Millipore cell (Millipore Corp.). Barbitol buffer (pH 8.6, ionic strength 0.075) was used with a run separation of 17 min at 100 volts. The protein bands were stained with Ponceau-§S dye and then quantified by using a Beckman/Spinco Analytrol with a micozone scanning attachment. Serum immunoglobulins. Immunodiffusion procedures for the determination of immunoglobulins IgA, IgD, IgG, IgM, and kanpa and lambda light chains were carried out by Dr. John L. Fahey and Dr. Roy Woods of the National Cancer Institute Immunoglobulin Center (Springfield, Virginia). The technique '