The author examined on the chief and heterogene reaction and the local anaphylactic phenomenon in the antiserum, immunized the rabbit by using the cow serum as the antigen, and obtained the following conclusion. 1. In the antiserum, its antigen is cow serum, there has been seen the specific and the unspecific heterogene precipitation reactions. The unspecific heterogene reaction was most strongest when the goat serum, the closed relation of cow serum, is used; stronger next when guinea pig and horse serums are used; and was in proportion to the frequency of injection. 2. Unspecific heterogene reaction was strong when serum euglobulin and pseudoglobulin are used as antigen and then the specificity of serum albumin was very strong. 3. The local anaphylactic phenomenon on the skin of the sensitizing rabbit by injecting the cow serum, has been seen in case of the goat, horse and guinea pig serums as the heterogene antigen, especially in case of the frequency of immunization. 4. Unspecific local anaphylactic phenomenon was noticed in case of the both antiserum of euglobulin and pseudoglobulin. Antiserum of albumin has species specificity of a higher degree, and showed the unspecific local anaphylactic phenomenon to the goat serum alone, the closed relation for cow serum.