ACTIVE IMMUNIZATION FOR THERAPEUTIC PURPOSES 209 



The general idea is to make an emulsion at the start that is stronger 

 than the one desired in the end, and subsequently to dilute this to 

 the required degree. The emulsion is transferred from the last tube to 

 a sterile test-tube, care being taken that the fluid does not come in 

 contact with the neck of the tube, as otherwise some organisms may 

 dry here and subsequently escape sterilization. This is then carried 

 out in a water bath at a temperature of from 60 to 65 C. An ex- 

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

 contents of the tube reach the desired point. A number of sterile 

 glass beads are 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. 190). As diluent I 

 use a 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 overnight 

 (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 ampoules, 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) Tuber- \j 

 cidin, bacillary emulsion. It is prepared by carefully grinding fresh ^ 

 cultures of the bacillus, after being dried in the vacuum, in an agate / ^ /I/ 

 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 1 part of bacilli); 1 c.c. of this preparation contains 

 5 mg. 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 

 14 



