THE formation of α-amylase in the endosperms of germinating barley seeds is controlled by endogenous gibberellic acid from the axial tissue1. Increases of soluble nitrogen in excised barley endosperms have resulted from the addition of gibberellic acid1–3. This communication shows that the proteolytic activity in seedlings, where the stored protein is in the cotyledons rather than in the endosperm, is influenced by growth regulators.