A CHEMICAL STUDY OF THE SPECIFIC ELEMENTS OF TUBERCULIN. I

1. The specific precipitin reaction and the skin reaction given by old tuberculin are attributable to two separate substances present in this material. The cause of the reaction first mentioned is a non-protein gum which will be fully described in the following paper. The cause of the skin reaction is probably but not surely a protein. 2. Methods which have been suggested for the standardization of tuberculin by precipitin or complement fixation reactions should be revised.