1. The presence and absence of cyanoglucoside in white clover are governed by a simple pair of factors which are designatedAc andac. 2. The cyanophoric character is completely, or almost completely, dominant to the acyanophoric. 3. The marked differences which occur between certain families, and in some cases between plants within the same families, in regard to their HCN content are probably due to modifying factors acting as intensifiers or diluents.