DESPITE the enormous strides that have been made by chemists during the last decades in the elucidation of many classes of plant products and the actual synthesis of individual members, the methods hitherto employed in the laboratory are so essentially different from those carried out by the plant that the synthetic processes of the living organism have come almost to be regarded as something fundamentally apart from those of the laboratory. The investigations on photosynthesis now being carried out in Liverpool by Prof. Baly and myself, although as yet of a quite preliminary nature, have, in my opinion, already shown that such a conclusion is entirely unwarranted and that the key to the problem of plant syntheses is to be found in the study of the energy transformations involved in the primary reaction wherein the plant brings about the fixation of atmospheric carbon dioxide. Apart from the purely academic interest of the subject, the problem of photosynthesis demands the attention of the community as a whole, for, with the elucidation of the reactions involved, the economic aspect of the question must inevitably become more prominent, and practical results of the greatest value to mankind may conceivably accrue.