BACTERIACE^E : THE TUBERCLE BACILLUS 309 



duced and present in the body as a result of previous contact 

 with the tubercle bacillus and its products. The tuberculous- 

 individual is therefore sensitized to tuberculin. The sensitization 

 may be local and confined to the tissue immediately surrounding 

 a solitary tubercle, or it may be general as a result of more ex- 

 tensive lesions. Tuberculin is applied to the skin mixed with 

 an equal amount of lanolin (Moro test), or applied to a scarified 

 point undiluted (Von Pirquet test), or injected into the sub- 

 stance of the skin in a dose of o.i c.c. of i to 1000 dilution (Ham- 

 burger intracutaneous test), or applied to the conjunctiva in a 

 dose of one drop of a freshly prepared i per cent solution of old 

 tuberculin (Wolff-Eisner or Calmette test), or finally it may be 

 introduced into the circulation by subcutaneous injection of 

 a dilution representing o.ooooi gram of old tuberculin, with 

 subsequent progressive increase of the dose up to o.oio gram if 

 reaction is not obtained. The local reaction is that of irritation, 

 evidenced by redness and edema, sometimes by vesiculation. 

 The general reaction is evidenced by malaise, irritation at site 

 of the lesion (increased cough in pulmonary tuberculosis) and 

 a rise in body temperature. The reaction depends upon the 

 tuberculin coming into contact with the specific ferment, and 

 the location, extent and activity of the tuberculous process are 

 important elements influencing the outcome of the various 

 tests. Tuberculosis in the eye causes such a violent reaction 

 to the conjunctival test that this method should never be employed 

 without first excluding ocular tuberculosis. The subcutaneous 

 test will often detect tuberculosis not revealed by the other 

 methods. It is, however, a more serious procedure than the skin 

 tests, which are indeed practically harmless. 



The various tuberculins are now extensively employed in 

 the treatment of tuberculosis, largely because of the favorable 

 results obtained by Trudeau. It is given subcutaneously every 

 5 to 7 days beginning first with a blank dose of salt solu- 

 tion and next with o.ooooi gram of tuberculin. The dose is 

 kept at the point at which the least general reaction possibly 



