Never has a medical discovery led within so short a time to such an amount of observations, as have been recorded since Koch first announced his discovery of a remedy against tuberculosis. Now that five months have elapsed since Koch's first paper and many observers can speak of three months experience, a survey of the applicability of "tuberculin" seems proper.
1. Its Diagnostic Value.
—Koch stated originally that no effects had been observed by him in healthy people from doses under about 1 centigram. He therefore considered a reaction of the system to a smaller dose, by fever, lassitude, diffuse pains, etc., absolutely characteristic of tuberculosis. The subsequent experience of others has shown that this rule is not without exceptions, hence it is at present only safe to say that "a systemic reaction on injection of less than 1 cg. of tuberculin in an adult is a very probable but