This is an exptl. investigation into the validity of Rich''s law which states that in tuberculosis,immunity and allergy are independent factors, and that the lesion is proportional to No. and virulence of bacilli x allergy Immunity Inoculation of virulent tubercle bacilli (human strain) into the anterior chamber of a normal rabbit causes an acute inflammation 14 days later which progresses to necrosis and case-ation. The degree of inflammation depends on the number of organisms. 50 times this dose in the immune-allergic rabbit causes an acute inflammatory reaction within 24 hrs. which subsides rapidly to be followed 2 weeks later by a mild inflammation. The initial reaction is an allergic one to the tuberculo-protein. The immune-allergic animal can deal with a larger dose of bacilli because it develops a certain degree of immunity but complete desensitization can be brought about without interfering with the immunity. Re-sensitization is liable to occur several months later. A high degree of cutaneous sensitivity to tuberculin indicates a high degree of ocular sensitivity, but a low degree of the former gives no indication of the sensitivity of the latter. An intense local reactivity to tuberculin can occur within the eye without stimulating the* cutaneous sensitivity. Promizole, a diamino-diphenyl sulphone, has a slight chemotherapeutic effect in ocular tuberculosis in the normal animal and a more marked effect in the immune-allergic animal. Streptomycin causes a dramatic improvement in the immune-allergic animal, especially when combined with promizole.