THE RELATION OF ACID-FAST BACILLI TO THE TRUE TUBERCLE BACILLUS.

Since the discovery of the timothy bacillus by Moeller in 1897, a good deal of attention has been directed to the group of so-called "acid-fast" bacilli, especially as regards their relation to the tubercle bacillus. The occurrence of certain acid-fast bacilli in milk and milk products, and the occasional presence in the sputum, in pulmonary gangrene, of other varieties, will be recalled as circumstances which at first led to mistaken bacteriologic diagnoses. In recent years the bacteria of this group have been well studied, both from the bacteriologic and the histologic standpoint, and differences between them and the true tubercle bacillus have been brought out; differences which, from the histologic standpoint, are rather slight. Moeller, who has consistently studied the acid-fast bacilli in their relation to the tubercle bacillus, and who can rightfully lay claim to an authoritative knowledge of the subject, has presented in a recent article1some