Detre,1 in 1908, proposed a modification of Pirquet's cutaneous reaction for tuberculosis. He suggested that simultaneous tests be made with bovine and with human tuberculin; in this manner, it might be possible to determine not only the presence or absence of tuberculosis, but also the type of the infecting organism.
Following this suggestion, several articles were published by different authors from various localities, in which data were given as to the relative frequency of positive reactions with each type of tuberculin. Table 1 shows a tabulation of these findings.
Analysis of the figures in Table 1 shows that there were many patients who reacted only to one type of tuberculin. A majority of the investigators found that the human tuberculin gave more positive reactions than the bovine tuberculin. The predominance of human reactors in one series and of bovine reactors in another may be explained either by the prevalence