196 ACTIVE IMMUNIZATION 



exposure of one hour is sufficient, counting from the time that the 

 contents of the tube reach the desired point. A small quantity of 

 sterile glass beads is now added, and the tube, tightly closed with a 

 sterile stopper, shaken by hand or with a machine, for about fifteen 

 to twenty minutes. The bacterial content is then ascertained, as 

 described above (see preparation of typhoid vaccine, p. 184). As 

 diluent I use an 0.5 per cent, solution of carbolic acid, taking care 

 that the final content of the latter, in the finished vaccine, does 

 not fall below 0.25 per cent. The tube is then allowed to stand on 

 end over night (so as to test the sterility of that portion of the tube), 

 and a culture made the next day, using a good-sized drop for each 

 tube, which is conveniently placed in broth or milk. The preparation 

 is finally provided with a label, giving the name of the organism, 

 and the titer of the vaccine, per 1 c.c. If desired, the vaccine can, 

 of course, also be put up in glass beads or ampules, each containing 

 a single dose of 1 c.c. In this form the material is usually furnished 

 by the dealers. 



While the common bacterial vaccines may be prepared in the 

 clinical laboratory from autogenous material, this is out of the 

 question in the case of the tubercle bacillus. Such a vaccine is best 

 obtained from the dealers, and is sold under the name of Koch's 

 Neu (new) Tuberculin (bacillary emulsion). It is prepared by care- 

 fully grinding fresh cultures of the bacillus, after being dried in the 

 vacuum, in an agate mortar, or in a specially constructed mill, when 

 the organisms are emulsified in equal parts of water and 50 per cent, 

 glycerin (100 parts of each for one part of bacilli). One c.c. of this 

 preparation contains 5 mgrms. of bacilli, and from it the required 

 dilutions are made, care being taken to sterilize the stock solution 

 before diluting, by exposure to a temperature of 60 C. for one hour. 

 As diluent a 0.25 per cent, solution of lysol in physiological salt 

 solution is used. 



The Injection. If the vaccine has been put up in bulk a small 

 quantity is poured into a small medicine glass that has just been 

 boiled, and the (sterilized) syringe charged from this; or this is 

 filled from one of the ampules directly. The skin is scrubbed with 

 soap and water and then with alcohol, or, as is now recommended, 

 painted with tincture of iodin at the site of the injection. My 

 favorite site for this is the district over the triceps, into the loose 

 subcutaneous tissue. In this region the injections rarely give rise 



