TUBERCULIN THERAPY 195 



We have learned the dangers of tuberculin treatment and its evident 

 limitations. We have, however, also in late years learned something 

 about the complex defensive resources of the living organism which tend 

 to the production of immunity, and how to call them into action, though 

 we are evidently as yet only on the threshold of the knowledge of im- 

 munization by vaccines in the treatment of chronic infections. Every- 

 thing we know, however, points to immunization as the goal toward which 

 our efforts should be directed. We have much to learn about tuberculin 

 treatment, but even in the present state of our knowledge, I am inclined 

 to think that the production of tuberculin immunity by the mild clinical 

 method is capable of favorably influencing the course of chronic tuber- 

 culosis, of prolonging life, and in many cases of aborting a commencing 

 infection or extinguishing the smouldering fires of a chronic infection. 



Available Preparations, — It is obvious, from the 

 great number of tuberculins that have been recom- 

 mended during the past twenty-five years, that none 

 is ideal, particularly for therapeutic purposes. Some 

 have fallen into disuse because of their greater toxic 

 properties; others have gained confidence because of 

 greater immunizing power ; still others have been sub- 

 jected to purification processes, in the hope of elimi- 

 nating toxic reactions and so on. Those preparations 

 which to-day enjoy greatest popularity, in the order 

 named, are Bacillen Emulsion or " B. E,," Tuber- 

 culin Riickstand or " T. R.," Bouillon Filtrate or 

 " B. F.," Old Tuberculin or " O. T.," Spengler's 

 Perlsucht Tuberculin, " P. T. O.," Dixon's Bacillary 

 Extract, and Tuberculinum Purum, " T. P." (see 

 Chapter XV) . The majority of tuberculin therapists 

 favor Koch's so-called new tuberculins, " B. E." and 

 " T. R.," believing that the resultant immunity is 



