1. Cf. Hahn, L., and Hevesy, G., NATURE, 140, 1059 (1937).
2. Cf. Robison, R. "The Significance of Phosphoric Esters in Metabolism" (New York, 1932), 66.
3. A detailed account of the experimental results obtained will be found in the dissertation of A. H. W. Aten, jun., to be presented to the University of Utrecht.