The mechanism of the action of the promoters has been studied and found to be due partly to the prevention of decay of the enzyme. The greater part of the action of the promoter is not due to this but to a specific stimulating action of the amino compound. Any possible hydrogen-ion effect has been eliminated by the use of a buffer. IOWA CITY, IOWA ... [CONTRIBUTION FROM THE CHEMICAL LAB~RATORY OF JOHNS HOPKINS UNIVERSITY 1 ORTHO-BENZOYL- ...