Recently Landau1has described an iodin color reaction in syphilis for which he claims a high degree of specificity as compared with the Wassermann reaction. On account of the simplicity of the test and the claims made it has attracted considerable attention, so that I have thought it advisable briefly to record my observations, although they have not by any means substantiated Landau's claims and show the test to be without practical value. Landau at first used iodized petrolatum for the test, prepared by mixing 5 drops of tincture of iodin in 10 c.c. of paraffin oil. To 0.2 c.c. of the serum was added 2.5 c.c. of this reagent and the test tube set aside in a dark place for from five to fifteen hours. Syphilitic serum, it is claimed, decolorizes the mixture, while the color persists a reddish yellow with normal serum. With this method Landau examined