Guinea-pigs infected with virulent tubercle bacilli were treated with a combination of antituberculous drugs and tuberculin. They were sacrificed at ten day intervals for 40 days after the initiation of the therapy. A histological study was made on the adrenal cortex in which the amount of ketosteroid in the cortex was measured by Deane's method. In the initial stage of the treatment a temporary decrease in the quantity of ketosteroid and cholesterol was observed in the cortex. Though this finding seemed to correspond with the so-called "shock phase" as designated by Selye, in the later stage, a remarkable increase of ketosteroid and cholesterol was noticed in the cortex. Judging from this fact, a considerable resistant state may be said to...