Various tests, which have been devised to estimate the functional capacity of the liver, have not proved to be of great clinical value. Most of these tests have been used in an attempt to study only one of the several well known functions of the liver. More recently some of the dyes have been employed as permeability tests for liver activity. Among the dyes advocated for this purpose have been methylene blue,1congo red,2indigo carmine,3and phenoltetrachlorphthalein. The last of these dyes has been most extensively studied. Rowntree, Hurwitz and Bloomfield4tried to estimate the permeability of the liver by the extraction of the dye from the feces after injection into the blood stream. This method was subject to many sources of error in the collection and extraction of feces and its use has largely been abandoned. The next step in advance was the modification of McNeil,5who used