Two years ago in a discussion at the National Association meeting,1 we called attention to the fact that all the surface cells, at least, of the body were in a condition of sensitiveness to the application of the poison which is known to-day as tuberculin, as evidenced by the different methods of tuberculin test which were before the medical profession—the eye reaction, the skin reaction, the urethral reaction, the nasal reaction, etc. We urged at that time that, if this were the truth, the discussion as to the methods of diagnosis which had been used were rather futile; that the method should be chosen which was the least dangerous, most ready of application and most easily observed and controlled.
A year later we called attention to the necessity of getting away from the qualitative studies of this method of diagnosis, and reducing it to some definite quantitative basis, and