BACILLUS OF TUBERCULOSIS. 295 



" The range of the patient's temperature is ascer- 

 tained by taking it at 8 A.M., 3 P.M., and 8 P.M. for 

 three or four days before making the test. The first 

 injection should not exceed 0.5 mg., and if any fever 

 is habitually present should be even less, and is best 

 given early in the morning or late at night, as the 

 typical reaction usually begins, in my experience, 

 within six or twelve hours. Such a small dose, while 

 it will often be sufficient to produce the looked-for rise 

 of temperature, has, under my observation, never pro- 

 duced unpleasant or violent symptoms. An interval of 

 two or three days should be allowed between each of the 

 two or three subsequent injections it may be necessary 

 to give, as reaction in very rare cases may be delayed 

 for twenty-four or even thirty-six hours. On the third 

 day a second dose of 1 mg. is given, and if no effect is 

 produced a third, of 2 mg., three days later. In the 

 great majority of cases of latent tuberculosis an appre- 

 ciable reaction will be produced by the time a dose of 

 2 mg. has been reached. If no effect has been caused 

 by the tests applied as above I have usually gone no 

 further, and concluded that no tuberculous process was 

 present, or at least not to a degree which need be taken 

 into account in advising the patient or which would 

 warrant insisting on a radical change in his surround- 

 ings and mode of life. If some slight symptoms, how- 

 ever, have been produced by a dose of 2 mg., it may 

 be necessary to give a fourth injection of 3 mg. in order 

 to reach a positive conclusion. Nevertheless, it should 

 be borne in mind that in a few cases the exhibition 

 of even larger doses may cause reaction and indicate 

 the existence of some slight latent tuberculous lesion, 

 and the test should not, when applied within the 



