It is well known that tuberculous caseous lesions have a tendency not to be easily absorbed or cicatrized in spite of the use of current effective antituberculous agents. Also this tendency seems to be more conspicuous in sclerotic caseous lesions than in nonsclerotic lesions. As is well known, the tuberculous lesion IS characterized by caseation and capsulation. According to our experimental studies, the caseous matter in the sclerotic lesion is so hard that it is not easily absorbed 1 ,3,7)

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... d also the capsule of the lesion is refractory to being easily digested or destroyed 3 ,8). These characteristics of caseous matter and capsules may be the reason for their stability and at the same time they inhibit the absorption or cicatrization of the caseous lesions 5 ). Furthermore, we have experienced that when the pre-caseous tuberculous lesions are irritated in the early stages, acute exudative inflammation in the lesions is increased or appears again and caseation doesn't occur. When moderate irritation is given repeatedly to such lesions combinied with chemotherapy, the lesions often attain cicatricial healing without any caseation. Also when some old stage lesions are repeatedly irritated, in which caseation already occurred acute inflammation again takes place in the lesion, causing the capsule of the lesion to be digested or destroyed by the infiltrating cells and the softening or liquefaction of caseous matter begins. If such repeated irritations are combined with chemotherapy, the possibility of cicatricial healing of these old lesions is much improved 5 ). From thes results, it may be reasonable to expect that the "irritation therapy", if adequate irritants were used, and if combined with chemotherapy, promotes 11