DURING the past few decades our thinking about tuberculosis has undergone changes which have influenced clinical practice, just as some clinical practices, which came upon us with overwhelming and almost empirical force, have changed our thinking about the tuberculous process. The most powerful of these has been specific chemotherapy. However, its success and its impact on the antituberculous effort could not be what it is had it not been preceded by equally important although less publicized developments. After one of the greatest triumphs in public health had been achieved in this country by the almost complete elimination of bovine tuberculous infection through government-sponsored control of the milk supply, the fight against the disease during the past 25 years has been decisively influenced by several other developments.
The first of these was the end of what might be termed the climatic era in phthisiotherapy. The migration of tuberculous patients to climatically