The search for a chemical agent with a direct action on the tubercle bacillus began with the early observation of Koch that gold salts had an inhibitory action on the in vitro growth of the organism. Colloid of gold preparations were thereafter used clinically in the treatment of various tuberculous lesions, including laryngeal and ocular tuberculosis, and some encouraging results were reported. Untoward reactions, however, were so frequent, and sometimes of such severity, that in 1926 Calmette protested against the use of these preparations on the ground that the frequent deleterious effects greatly outweighed any favorable clinical action. Various dye preparations were later used in the treatment of ocular tuberculosis, but the reported results were not sufficiently encouraging to arouse any great enthusiasm for their use. In 1932 Wells1 reviewed the literature on the chemotherapy of tuberculosis and concluded that of the many remedies proposed up to that time