In order to study the term of existence of tubercle bacilli in excrements, the author coducted model experiments on 51 materials, by means of Kudo's culture method. Tubercle bacilli which were put in the excrements lost their living power gradually, the number of the bacilli decreased as times went off and finally they disappeared entirely. The experiments were conducted at room temperatures of different seasons. The term of existence of the bacilli in the experiments which started in December was of 231 days at the maximum, the one started in March was of 136 days at the maximum, the one in May was of 72 days at the maximum, and the one in August was of 167 days at the maximum. Therefore, it was found that by seasons there were differences in the term of existence and the bacilli seemed to have the tendency to live longer in cold weather, whereas they seemed to exist for a shorter period in hot weather. The author does not intend to say that the results of his experiments give directly the data for the longevity of tubercle bacilli in patients' sputa that appear in the excrements of receptacle, however, it may be considered as one of the basic facts, through which the longevity of the bacilli can be infered.
