During the eight years that followed Roberts'1 observation of an increase in serum phosphatase in the presence of jaundice, numerous statistical studies and many experiments have been carried on to evaluate it as an aid in differential diagnosis. The mechanism accounting for the rise in serum phosphatase has not been satisfactorily described. Roberts stated that there is a pronounced increase in phosphatase in obstructive and in catarrhal jaundice. He suggested that this denotes nothing more than an expression of the presence of bile constituents in the blood, since bile itself has a high phosphatase content. In 1933 he2 stated that this premise does not explain all the facts. He reached the conclusion, based on a study of 52 cases, that toxic, infective and catarrhal jaundice may be readily distinguished from jaundice of the obstructive type by characteristic values of phosphatase.
Subsequent investigators have not found this to be