Two strains of transplantable leukemia in C58 mice described in the Part I, OHS-LL (lymphocytic) and OHS-ML (myelogenous), were compared as to the resistance and preservation of leukemic cells by means of bioassay experiments. Both leukemic cell lines were not viable beyond 24 hours at room temperature, and rapidly lost transplantability at 65℃. For the preservation of leukemic cells it was more appropriate to keep them as frozen spleens or animals than to keep them as cell suspensions. OHS ML withstood for 60 days and OHS-LL for 47 days at -80℃., and it would be possible to preserve them for a longer period. OHS-ML was not transplantable below pH 5 and OHS LL below pH 3, indicating inferior resistance of the former to an acid solution. Both leukemic strains became negative for transplantation in NaCl solutions at 0% and over 10% , and showed no difference in osmotic fragility. Both cell stains proved to be cell-graftable after 5 times of freezing and thawing at -30℃. for 15 minutes, but not after 5 times of the same procedure at -30℃. for 60 minutes. Both cell lines were not transplantable after lyophilization. The lethal X-ray irradiation dose was 8,000r against OHS-ML and 3,000r against OHS-LL. OHS-ML became inactivated by formalin, trichloroacetic acid and marsonin at the concentration of over 10(-1)%, 10(-2)%, and 10(-3)%, and similarly OHS-LL at the concentration of over 10(-2)%, 10(-1)%, and 10(-2)%, respectively.