The chronologic relation between the appearance of a positive reaction to the tuberculin test and roentgen evidence of the childhood type of pulmonary tuberculosis has not as yet been subjected to careful clinical investigation.
The general impression obtained from the majority of textbooks and treatises on tuberculosis is that the positive cutaneous reaction coincides with or antedates roentgenographically recognizable evidence of the primary tuberculous infiltration of lung tissue. If this impression is correct, the logical inference is that cutaneous allergy to tuberculin has already become manifest or is coincidental with the time when the primary pulmonary infiltration has attained sufficient magnitude to be identified by means of the roentgenogram.
During a study of infants exposed to tuberculosis1 an opportunity was presented to follow these children with roentgen examinations and tuberculin tests before, during and after the development of the primary complex of tuberculosis.
The children were referred to the