Effect of the Roots on the Production of Auxin by the Coleoptile.

Laboratory, and especially Mr. Philip Abelson, who determined the activity of the various phosphorus samples. We appreciate the interest of Dr. John Lawrence and Mr. Paul C. Abersold and their assistance with x-ray exposures. The investigation was aided by a grant from the Board of Research of the University of California. 'Lawrence, E. O., and Cooksey, P., Phys. Rev., 50, 131 (1936). 2 Chiewitz, O., and Hevesy, G., Nature, 136, 754 (1935). 3 Scott, K. G., and Cook, S. F., Univ. Calif. Publ. Physiol., 8, 135 (1936). 4 Taylor, Herbert A., Witherbee, W. H., and Murphy, J. B., Jour. Exp. Med., 29, 53 (1919). 5 Aubertin, A., and Beaujard, C. R., Soc. Biologie, June 11 (1904). 6 Englebreth-Hohm, J., Experimentelle Studier over den Overf#rbare H#seleucose, Levinn and Munksgaard, 1933.