After having once injected cow's serum antigen toward both a normal rabbit, as well as a rabbit with impediments in the reticuloendotherial function due to ink injection, I examined and have taken observations on such matters as Congored Index, total serum protein density, precipitin value, as well as quantitative changes that happened; which, offered results as follows: 1. In case of a normal one, the total protein density of antiserum, along with γ-Globulin quantity, almost showed a parallel relation with the precipitin changes. In those viccisitudes that have occurred in α- and β-Globulin as well as Congorccl Index, no definite tendency could be detected. 2. In case of a splenorectomized rabbit, there occurred an increase in Congored Index, accompanied with a decrease in the total serum protein density, albumin, as well as γ-Globulin, on the day that followed the operation. Moreover, an increase has taken place in β-Globulin. 3. In an ink-filled rabbit, there could be seen, within a day of injection, certain increase in the Congored Index, along with a decrease in total serum protein density, albumin or γ-Globulin. 4. In those rabbits who underwent splenorectomy and ink-injection, no serum protein acting parallel with the precipitin changes, as seen in a normal one, could be observed. 5. The precipitin production has proved at its maximum in a normal rabbit, in 20 days after antigen injection; while, in 20-30 days in case of an operated one; and 14 days in the injected rabbit, among these three groups, the injected rabbit showed maximum; next, normal one, and lastly, rabbit who suffered the operation. 6. At 85 th days after the injection, of antigen, a decline in precipitin has proved marked in all the three groups, esp., very eloquent in an operated rabbit. 7. From the above results, it may roughly be concluded that a close correlation exists between γ-Globulin and antibody; further, the role of reticuloendotherial system as mother ground for antibody production may be considered with some significance.