216 ACTIVE IMMUNIZATION 



of the reaction, and which accordingly vary from one to two weeks. 

 In the event of a marked reaction, it is best to repeat the last dose, 

 or to increase this only very slightly. A reversion to a smaller dose 

 is to be avoided, and it is better, if need be, to wait a week longer 

 before the next injection is given. In the light cases it is thus possible 

 to run up to a dose of 1000 milligrams without much trouble, while 

 in the presence of more advanced lesions this is more difficult; when 

 the higher doses are reached the intervals betw y een the injections 

 may have to be lengthened to a month or even longer. The treatment 

 is virtually considered at an end when the patient can stand a dose 

 of 500 milligrams without marked systemic reaction. 



New Tuberculin. 1 c.c. of new tuberculin represents 5 milligrams 

 of the dry powder. Koch recommends that the injections be started 

 with a dose of 0.0025 milligram. To this end the original product 

 is diluted with sterile water to the required degree, so that the 

 amount to be injected is less than 1 c.c. in bulk, as larger quantities 

 favor the development of local infiltration. For convenience' sake 

 w r e can start with a dilution of the original product of 1 in 10 (A), 

 1 c.c. of which in turn is diluted 1:10 (#), and of this again 1 c.c. 

 in the same proportion (C); 1 c.c. of A then contains 0.5 milligram, 

 1 c.c. of B 0.05, and 1 c.c. of C 0.005; 0.5 c.c. of the latter dilution 

 being thus the initial dose. 



The injections are at first given four days apart, and later when 

 reactions begin to appear (i. e., when amounts varying between 

 a tenth and one-hundredth part of a milligram are injected) at 

 intervals of eight days, in gradually increasing amounts, such as 

 4^ milligram; ^ T f , ^fa, ^, yfo, T fo, yfo, ^, T V ^, etc., 

 exactly as was customary with the old tuberculin. Koch advocates 

 that the immunization be continued until the patients can take 

 20 milligrams of the dry powder without any reaction. 



Point of Injection. As in the case of the other bacterial vaccines, 

 the injections can be conveniently given into the loose subcutaneous 

 tissue in the district over the triceps, or in the back on a level with 

 the angle of the scapula. Lowenstein states that the injections 

 may be advantageously given intravenously, that the infiltration 

 of the skin is thus obviated, and that the reactions are of briefer 

 duration. 



In advanced cases of pulmonary tuberculosis a combined treat- 

 ment with old and later with new tuberculin has been recommended. 



