In previous communication (Journal of Biological Chemistry, March, 1922) Fulmer and Nelson showed that the water extract of alfalfa is much richer in the yeast growth stimulant, Bois, than is the 95 per cent alcoholic extract of the same material. In the work here described two extracts were prepared as follows from alfalfa which had been previously extracted with ether. Extract A was an extract by long extraction with absolute alcohol. Extract B was an extract prepared by long extraction of the absolute-alcohol-extracted material with water. Both extracts showed optimum concentrations for maximum stimulation and were about equally potent. Combinations of the two extracts were much more potent than the optimum concentration of either alone. Detailed studies are being made of the properties of the two extracts. Bois is not a single substance but is composed of at least two materials. Bois A is soluble in absolute alcohol and in water. Bois B is insoluble in absolute alcohol and is soluble in water
