Abstract
A sharp increase in lung-wt. was observed during exptl. tuberculosis in mice infected intraven. This phenomenon was counteracted by the admn. of antituberculous drugs. The action of the drugs was directly proportional to the dosage used in most cases. A quantitative method of evaluation of antituberculous activity of drugs is descr. on this basis. Isoniazid and 2 of its derivatives were studied by this method. Isoniazid methanesulfonate is more active, and isoniazid parabenzaldehyde less active, than isoniazid.