Human tubercle bacilli sensitized rabbits were super-infected with the same bacilli intravenously and were subjected to SM-therapy. The infected lungs were removed at certain intervals and examined histologically. 1) Tuberculous changes developed more intensively and earlier in the lungs of the rabbit super-infected with the bacilli than those in the lungs of the animals infected only once with the bacilli. In the super-infected and non-treated animals, the tubercle bacilli were disintegrated and reduced in their number mainly due to allergic reaction within a week after the reinoculation, while from. the 2nd week they began to propagate" markedly as soon as the animal fell into anergie state followed by cavity formation, one of the most severe manifestations of tuberculous changes of the lungs. From the 6th week on, the lesions became localized. This was considered as one of the healing processes of tuberculous lesions. 2) In the animals subjected to SM-treatment simultaneously with the super-infection, the same tissue lesions were observed as in the non-treated animals in the early stages, while the lesions rapidly became reduced in size and severity 2 weeks after the reinoculation without further propagation of the tubercle bacilli, and there after the tubercles were resorbed and disappeared
