From these facts it can be considered that rat ascites tumor contains antigenicity common to rat tissues and specific one which is independent in each tumor. By means of lyophilizing specific antigenicity to each tumor is vanished. However, species-specific antigenicity, which is common to rat tissues, is not lost. And by means of formalin solution antigenicity common to rat tissues can be lost. Moreover, in the immunization cases with formoled tumors species-specific common antitransplantability only vanishes and specific one to each tumor exists still strong. These data suggest that species-specific antigen and specific antigen to each tumor have each characte ristic nature which resists differently chemical and physical treatments.
