The various vital reactions occured to the sensitized animal were serologically observed on the sensitization of animal (rabbit) by the heterogeneous organic (gallbladder and colon) antigen. And the results were as follows. 1. The antibody reacting to the heterogeneous organic antigen was rapidly produced for 1-2 weeks after the beginning of the sensitization, on the sensitization by the heterogeneous organic antigen, it's antibody titer became the most high titer 3-4 weeks of the continuous sensitization and it continued for the fixed period. 2. As the vital reactions occured to the sensitized animals with the production of heterogenous antibody, the loss of weight decline of hemoglobin value and decrease of erythrocyte count, leukocytosis in the leukocyte count, lymphocytosis in the classification of leukocyte, decrease of total serum protein value and increase of γ-globulin in the serum protein picture and the vicissitude of α-, β-globulin preceeding to γ-globulin were observed. 3. The vicissitude of complement titer on the sensitization by the hetrogeneous organic (gallbladder and large intestine) antigen scarecely showed the change and it slightly showed the decreasing tendency at 5-6 week after th sensitization. 4. The heterogeneous organic antibody considerably showed the organic peculiarity to it's organic antigen on the crossreaction with each organic antigen. And the common antigenicity was partly observed on each organic antigen.