Smith, Doyle C. (Kansas State University, Manhattan), V. D. Foltz, and T. H. Lord. Two lytic factors involved in induced synergistic hemolysis in normally nonhemolytic staphylococci. J. Bacteriol. 88:1700–1704. 1964.—Synergistic hemolysis of “normally nonhemolytic” staphylococci results from the combination of two factors: Z, produced by hemolytic staphylococci that elaborate a secondary hemolytic zone on blood-agar, and T, produced by nonhemolytic staphylococci. Factors Z and T are produced in supernatant fluids of broth cultures and are detected by the synergistic hemolysis (SH) test. Complete lysis of sheep red cells is observed in the SH test only when both factors Z and T are present. Production of Z and T is greatly enhanced by the presence of 10 or 20% CO2 during incubation. Both Z and T are heat-stable, withstanding 100 C for 15 min. Neither factor is precipitated by saturated Na2SO4 or (NH4)2SO4. Hydrogen ion concentrations between pH 5.0 and 8.5 do not exert any effect on the two factors. Factor Z is produced in greater quantity than factor T. It is suggested that factors Z and T are not proteinaceous, enzymatic, or lipid in nature.