1. THE METHOD WHICH COMPRISES DESTROYING THE CELL WALLS OF A PLANT MATERIAL SELECTED FROM THE GROUP CONSISTING OF CHLORELLA, LOTUS SEEDS AND BAMBOO SHOOTS AND EXTRACTING SAID PLANT METERIAL WITH WATER, THEREBY FORMING AN AQUEOUS EXTRACT TO A PH VALUE OF BELOW ABOUT 4.5; AND ADDING TO THE THUS ACIDIFIED AQUEOUS EXTRACT A WATERSOLUBLE SALT OF GLYCYRRHIZINIC ACID SO AS TO FORM A PRECIPITATE INCLUDING GLYCYRRHIZINIC ACID AND A SUBSTANCE WHICH GIVES A POSITIVE SEDIMENTATION REACTION AND A POSITIVE REACTION TO THE DYEING EFFECT OF PROTEIN REAGENT, THE NINHYDRIN DYED IMAGE OF SAID SUBSTANCE ON PAPAPER ELECTROPHORESIS BEING CLOSER TO THE CATHODE THAN IS LYSINE, AND THE MAXIMUM ABSORPTION THEROF UNDER ULTRAVIOLET BEING AT ABOUT 259 MU.