We, by frequent injection of a cow's serum antigen into a rabbit, and examining such as the coefficient of congored, total protein density of anti-serum, changes in precipitin as well as changes that occurred to the fraction of serum protein, electrophoretically and at a certain lapse of time; and having taken an observation on their correlations, succeeded to arrive at the following results; 1. Both γ-Globulin as well as precipitin changes proved as parallel. The same tendency has been detected in β-Globulin, but not so marked as in the case of γ-Globulin. 2. A overfunction of reticuloendotherial action has been occurred, caused by immunology; in general, that sort of hyperbole can be seen from 10-30 days after the 1st injection of antigen. 3. The total protein density of serum-antigen has increased or decreased side by side with changes of precipitin, but changes in Albumin and Globulin have proved no such steadfast trend. 4. A markedly low case in precipitin formation has been discovered in a rabbit which possessed a very slight amount of γ-Globulin within normal serum, previous to antigeninjection. 5. From the above results, it was found that a close connection exists between those Globulins and and antibody, esp., between γ-Globulin and antibody; moreover, the fact that the function of reticuloendotherial system as springhead of antibody. Further, as a cause of individual difference in antibody formation, the amount of retained (possessed) normal γ-Globulin was considered significant.