Attempts to measure the functional powers of the liver by various tests have occupied a rather prominent position in recent medical literature. The phenoltetrachlorphthalein test during the last few years has given promise of being the most valuable of the various methods proposed. Abel and Rowntree,1 in 1909, discovered that, except for traces which appeared in the urine, this dye was apparently eliminated only by the liver after subcutaneous or intravenous injection of the disodium salt. They also found that the substance was nontoxic to dogs, even when injected daily for several months in very large doses. They noticed, moreover, that subcutaneous injections of the dye had a prolonged laxative action. Several years later Rowntree, Hurwitz and Bloomfield,2 Whipple, Mason and Peightal,3 and Whipple, Peightal and Clark4 undertook clinical and experimental investigations on the elimination of this dye by the liver and its applicability as a clinical test for liver