Many species of bacteria pathogenic to the eye are susceptible to the newer chemotherapeutic agents—both to sulfonamide compounds and to the products of molds ; a few (Bacillus pyocyaneus, Morax-Axenfeld diplobacillus, Haemophilus influenzae and Friedländer's bacillus) are susceptible only to sulfonamide compounds. The degree of sensitivity of the species of the infecting organism to the drugs is but one of a number of factors which influence the therapeutic result. Also of importance are initial differences in sensitivity of strains of the same species to the selected compound and subsequent differences developing during the period of treatment, due in part to the maturation of the bacteria. Other factors are the number and the virulence of the infecting organisms, the amount of protein breakdown products or pus and the quality of the cellular and humoral body defenses. Some of these factors cannot be evaluated at all, and others require time-consuming tests. In view