Pediatricians and public health authorities alike have recently displayed renewed interest in tuberculous infections in children. Recent studies both in this country 1 and in France2 have shown beyond doubt that administration of antituberculous drugs to children with positive tuberculin tests decreases the chance of active tuberculous disease appearing within the ensuing year, so that it becomes desirable to detect infection with Mycobacterium tuberculosis soon after it has taken place. This can best be done by carrying out tuberculin tests at rather frequent intervals, e.g., once or preferably twice a year. There is now, more than ever before, a clear need for a simple, reliable method for performing tuberculin tests, so that they can be performed repeatedly on large groups of young people.The tuberculin patch test which, it was hoped, would serve such a purpose has proved disappointing, yielding as it does both false positive and false negative readings.3,4In 1951 there appeared in the Lancet an article entitled "The Multiple-Puncture