MYCOBACTERlACEiE: THE TXffiERClE BACILLUS 323 



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 apphed 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 tubercuhn, with sub- 

 sequent 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 con- 

 junctival 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 solution and next 

 with 0.00001 gram of tuberculin. The dose is kept at the point 

 at which the least general reaction possibly recognizable occurs, 

 or just below this amount, the general purpose being to induce 

 an inamunity to tuberculin. It is often posssible to begin with a 



