“…We believe to have shown beyond doubt, however, that the changes in oxidation-reduction potentials measured in suspensions of Chlorella are connected in some way or other with processes, particular to the mechanisms of photosynthetic carbon dioxide reduction. They are not, however, connected directly with the effects of over-all photosynthesis, an observation already reported earlier by WASSINK for experiments with purple bacteria (13,32). In addition, our experiments strongly support the idea that, at least during certain phases of the induction period the potentials are a reflection of the formation of reducing compounds by the primary photochemical process which are suitable as hydrogen donors for carbon dioxide reduction.…”