VACCINE OR OPSONIC THERAPY 107 



minute doses. These are gradually increased at inter- 

 vals of three or four days, with the object of increasing 

 the patient's resistance to the tubercle germ and its 

 products until complete immunity is attained. 



Various forms of tuberculin are designated, depending 

 upon the method of preparation and the constituents 

 retained. 



Old Tuberculin (Tuberculin 0. T 1 .). This is the orig- 

 inal tuberculin of Koch and contains the toxins and sol- 

 uble secretions of cultures of tubercle bacilli grown 

 on glycerin bouillon. The cultures are sterilized by 

 heat and the germs removed by nitration. 



New Tuberculin (Tuberculin T. R.). This is pro- 

 duced by pulverizing dried tubercle bacilli, dissolving 

 them in salt solution by repeated centrifuging, and 

 decanting the clear liquid. It contains the entire sub- 

 stance of the germ. 



Koch's belief is that the use of old tuberculin, consist- 

 ing as it does of toxin only, produced immunity to the 

 toxin alone, while the proper employment of the new 

 tuberculin produced immunity to both toxin and germ, 

 inasmuch as it represents the entire germ and not the 

 soluble products alone. 



The Use of Tuberculin in Treatment. As will be 

 shown in the study of tuberculin in diagnosis, large doses 

 produce a reaction, with fever, inflammation at the site 

 of injection and the site of the lesion. Such reaction, 

 if profound or if repeated, will do great injury. There- 



