The recent articles by Corper on a new method for the cultivation of the tubercle bacillus have stimulated interest in what has always been a difficult and tedious performance. Since cultural methods hitherto have not been much more delicate in the detection of tuberculosis than the microscopic examination of smear preparations of sputum and tissues, the latter has remained the popular choice, especially in ordinary hospitals. The guinea-pig inoculation method is unhandy and too expensive, and in any case detection of the bacilli in the inoculated animal has to be done by a microscopic smear preparation. The examination of smears of sputum and tissues seldom gives positive results in those cases where doubt exists. A negative result from a microscopic examination of a smear cannot be relied upon.