Estrogenic Substances from Plants: I. Glycyrrhiza††The authors wish to acknowledge the technical assistance of Mr. Calvin L. Butler and Miss Lucille E. Mullen of the Lydia E. Pinkham Research Laboratories in the bioassays and of Professor Helen S. French of the Chemistry Dept., Wellesley College, in the spectrophotometric analyses. The authors are iidebted to the Lydia B. Pinkham Medicine Co. for supplying raw materials and to Parke Davis and Co. for supplying the crystalline estriol used in this investigation.