2 Until recently, the Japanese authors of Akamatsu's school divided the phosphatases into phosphomonoesterases, phosphodiesterases, pyrophosphatases and phosphoamidases and claimed to have demonstrated the specificity ofthe several enzymes. As the whole ofour experiments were made with sodium ,-glycerophosphate as substrate, the enzymes studied by us should be called, according to the terminology ofthe Japanese authors, phosphomonoesterases. However, in a recent work by Hotta [1934] it is shown that the specificity of the phosphatases is not determined only by the nature of the bond which unites phosphoric acid to the alcoholic residue but also by the chemical nature of the alcoholic residue itself. Until such time as the question is settled, we prefer to retain the generic denomination of phosphatases. Biochem. 1935 xxix (1491) 95

IN recent work Davies [1934] found that the autolysed extracts of liver and spleen hydrolyse sodium /-glycerophosphate at two different optima of acidity, namely PH 45-5 and PH 8*9, and he expressed the opinion that there were two different phosphatases; however, it was not possible for him to purify the extracts in such a way as to obtain from them two fractions each containing one of the two distinct enzymes. An analogous fact had been observed for the phosphatases of hog kidney by Kurata [1931] who had succeeded in obtaining, by adsorption processes and from the same starting material, two different enzymic solutions, one having an optimum of phosphatase activity at PH 3, the other at PH 9. Recently some Japanese authors of Akamatsu's school [Usawa, 1932; Munemura, 1933, etc.] came to the conclusion that the enzymes which hydrolyse the monoesters of phosphoric acid belong to three types:

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