ANTIGENS OF ARBACIA SPERM EXTRACTS

1. Extracts were prepared from Arbacia sperm by several procedures. These were tested for antigenic composition by diffusion against anti-Arbacia sperm rabbit serum on Ouchterlony plates and by means of immunoelectrophoresis in agar gel.2. Extracts prepared by freeze-thawing the sperm followed by low speed centrifugation produced a maximum of four precipitin bands. It is concluded that such extracts contain at least four soluble antigens.3. Seminal plasma revealed seven arcs in an immunoelectrophoretic experiment, and a maximum of three bands on Ouchterlony plates. Two such bands join bands from "frozen-thawed extracts."4. Extracts prepared by heating sperm at 100° C. yielded at the most one band. This antigen seemed to be common to several other extracts.5. Nucleoprotein (Mirsky and Pollister) and histone failed to form precipitin bands.6. One of the four bands in frozen-thawed extract is associated with material sedimented at 26,000 x g.