198 ACTIVE IMMUNIZATION 



with a nipple the organisms are forced into suspension, when the 

 vaccine is transferred to a tube, to be killed in the usual manner. 

 Estimations of carefully counted suspensions obtained by centrif- 

 ugation in the above manner gave the following results: 



Per cent. Bacillus per c.c. 



Staphylococcus aureus and albus ... 1 10.0 



Streptococcus hemolyticus 1 8.0 



Gonococcus 1 8.0 



Pneumococcus ........ 1 2.5 



Bacillus typhosus . 1 8.0 



Bacillus coli "... 1 4.0 



With different speeds different standards will, of course, be 

 obtained. 



After the strength of the emulsion has been determined the 

 material is diluted to the desired degree with carbolic acid, such 

 that the final content of the latter shall be between 0.25 and 0.5 per 

 cent. This then constitutes the vaccine and keeps practically indefi- 

 nitely. The manufacturers now furnish this in little ampoules 

 containing the requisite dose. 



Dose and Method of Vaccination. For practical purposes Wright 

 recommends a first injection of 750,000,000 to 1,000,000,000 organ- 

 isms, and double this dose for the second treatment. These injec- 

 tions may be made practically anywhere, where the skin is not bound 

 down tightly. I have thus found the outer aspect of the upper arm, 

 where the skin lies quite loose, a favorable locality. Others inject 

 in the loin, or in the back, in the neighborhood of the shoulder-blade. 

 The injections are, of course, to be made with a sterile syringe, and 

 after having closed the area to be injected with soap and writer 

 and alcohol, or, as has recently been recommended, after painting 

 with tincture of iodin. The needle puncture is covered with collo- 

 dion. 



Fearing that the injection of a large dose of organisms may at 

 first be followed by a diminution in the protective substances of the 

 body (negative phase), owing to an interaction between the normal 

 antibacterial substances and the bacterial antigen, and that the indi- 

 vidual may thus be temporarily less resistant to the corresponding 

 infection, Wright has suggested that, in persons who are likely to be 

 exposed to typhoid infection soon after the first injection, this should 

 be smaller than usual, and that its effect is to be supplemented later 



