Abstract
The procedure of purification of the substance in urine, giving rise to the bromine color test, is described. The substance was broken down by liver histidase. The decarboxylation of the substance was followed in manometric expts. and the fluids were tested for their action on the isolated fowl''s gut. If incubated with histamraase the effect on the gut was nullified. The nitranilic acid precipitation method was applied to the urine substance. The color produced by the bromine reaction is evidently due to histidine. The clinical significance of this is discussed.