I. A Comparative Study of Precipitin Reaction (Ring test and Mixture test) with the Use of U-tube

By devising a precipitin reaction with the use of U-tube and using Ogata's antigenantibody dilution test, ring test and mixture test have been compared, the results of which are as follows: 1) In the precipitin reaction with the use of a U-tube, antibody titer centering around the "binding zone" has been found two times more dilute than that observed in the mixture test. and the titer has almost coincided with antibody titer of the ring test. 2) This U-tube test suits convenience to manipulate tnan the ring test, and moreover, it affords relatively better observation results. 3) The U-tubes are washed out easily than capillary tubes. 4) The precipitate obtained by the precipitin reaction has presented mobility by electrophoresis equivalent to γ-globulin of original serum.