1. Lang, A.: Naturwiss.43, 284 (1956).
2. Part of the experiments was done with a mixture of gibberellin A and gibberellic acid, kindly supplied by Dr.F. H. Stodola, U. S. D. A. Northern Utilization Research Branch, Peoria, Ill., part with a preparation containing gibberellic acid only, obtained through the courteousy of Dr.Curt Leben, Lilly Research Laboratories, Indianapolis, Ind.
3. Rye was treated either by applying a drop of gibberellin solution to the base of the blade of the youngest fully expanded leaf, or by immersing a leaf blade, with the tip cut, into the solution. The other plants were treated by applying the solution to the apical region of the shoot. Most experiments were carried out by Mrs.Patricia B. Finn.