IN recent years there have been one or two reports of the occurrence of free glyceric acid in higher plants. Balansard1 identified the acid as the diuretic principle in the pods of broad bean (Vicia faba L.) but gave no indication of the amount present other than could be inferred from the diuretic effect. Isherwood, Chen and Mapson2 isolated D-glyceric acid from cress seedlings; they found that it was present in amounts ranging from 5 to 50 m. equiv./kgm. of fresh weight in seedlings cultured for 5 days at 20° C. in the dark on 0.04 M sodium bicarbonate solution. Palmer3 isolated D-glyceric acid from tobacco leaves (Nicotiana tabacum var. Connecticut) grown in the shade and estimated the quantity present to be of the order of 5–15m. equiv./kgm. (fresh weight).