1) The seronegative rabbitsserum in the Browning, Murata and M.K.R. II. tests is not influenced by the injection of Bagnon-Stark and this result remains unaltered even after three consecutive injection. 2) The effect of this medicament upon the nop-specificity in the Murata and the M.K.R. II. tests is observed after the first injection. The non-specificity in the Murata test disappears or shows negative tendency in 30 seconds after the injection, and the similar result is recognised in 1 hour after the injection in the M.K.R. II. test. 3) The duration of time before the disappearance of non-specificity in the two tests varies according the strength of the reaction. The weak positiveness before the experiment disappears in 3 hours after the injection in either of the two tests. But in the case of strong positiveness 10 hours is required to shows the negative tendency after the injection, and in either of the two cases the complete disappearance of non-specificity is observed in 24 hours after the infection. 4) The effect of Bagnon-Stark on the rabbit syphilis that has shown strong positiveness in the Browning, Murata and M.K.R. II. tests is wholly null and void. 5) The disappearance of non-specificity in the Murata and the M.K.R. II. tests by the injection of Bagnon-Stark is probably due to the alteration of organic metabolism as well as to the fall of temperature in the rabbit.