Rabbit was immunized by fish- and bullinsulin, and the complementfixation has been examined by Ogata's antigen antibody dilution method (the insulin complementfixation is succeeded when the fixing time of antigen, antibody and complement is to be acted during one hour on 37℃ and after that 24 hours on 3℃). 1) There is some difference in Ogata's equivalent zone on the insulin complementfixation between the insulin of the same kind used in immunity as antigen and other kind insulins (that is, cross reaction). Besides, it is moved according to the immunity process, and it is almost 1~6 unit. 2) The title of the antibody is 1:8~160 in the insulin of the same kind and 1:40 in
the cross reaction. 3) The title of the antibody of the complementfixation to make the examination antigen, when the extracted fluid of the same animal protein produced the insulin is 1:10~20 in the same serum. 4) The title of the antibody on the cross reaction about the insulin immunized rabbit's serum which was absorbed with the extracted fluid of the same animal protein has produced the insulin is almost equal to one before absorption. 5) The title of the antibody by the extracted fluid of the animal protein produced the insulin of the insulin immunized rabbit's serum which was absorbed by the other kind insulins, (it is dif-ferent from the insulin used in immunity) is almost equal to before. 6) As the insulin will be analyzed with electrophoresis, it will be able to separate the insulin protein and impure proteins. 7) The insulin antibody has been also declared by the insulin complementfixation about the crystal insulin immunized rabbit's serum, too. As mentioned above, the insulin protein has the immunity and the insulin preparats contain some impure things, which causes impure protein antibodies with the insulin protein antibody.