Effect of light on the uptake, utilization and transport of sugars. —The effect of light on the uptake of saccharides, their incorporation into insoluble fractions and their transport by green tissues has been studied under conditions of complete inhibition of the photosynthetic assimilation of CO2. Such conditions were obtained by means of either an inhibitor of O2evolution (CMU), or by running the experiment in CO2-free atmosphere. When Wolffia arryza plants are incubated with glucose-C14, light stimulates the incorporation of C14into all fractions examined, and especially into the polysaccharides, like cellulose,' which are synthesized outside the chloroplasts.