Abstract On the functional activation of germinating seeds. Note V. NADH2:— and NADPH2: DIP oxidoreductase activity. - NADH 2:— and NADPH 2 : DIP oxidoreductase activities are ascertained, in Pisum sativum and Zea mays, in the acetone precipitates obtained from extracts of dry and germinating seeds. Such activities are always present and increase during the first days of germination. In the mays, where in the embryo the reduction of the DIP is particularly high, at the point that it could be measurable on less than 1 mg of material, the NADPH 2 : DIP oxidoreductase activity prevails. In the pea, the NADH 2 : DIP oxidoreductase activity prevails. Endosperm of mays and cotyledons and embryonic axis of pea have NADH 2 : DIP and NADPH 2 : DIP oxidoreductase activities which, referred to the dry weight, are of the same order of extent and about thirty-fifty times inferior to those of the embryo of mays.