248 APPLIED IMMUNOLOGY 



quently for months or years. There is substantial evi- 

 dence that prophylactic typhoid immunization pro- 

 tects the individual for at least three years. The 

 duration of immunity may be determined by cutane- 

 ous allergic tests and by serological reactions, includ- 

 ing the opsonic index. 



Modes and Technic of Administration of Bac- 

 terins. — Bacterins have been administered subcutane- 

 ously, intravenously, orally and per rectum. The 

 last three methods are not in general use, in spite of 

 sporadic marvellous results, nor do they appeal 

 strongly on immunological grounds, and consequently 

 seem not destined to become popular. Subcutaneous 

 administration is the procedure usually practiced. In 

 the event of mixed infections, multiple bacterins of 

 the respective pure bacterial cultures may be prepared 

 for alternate or indicated inoculations, or a mixed 

 bacterin proportionately compiled of the various in- 

 vading microorganisms may be employed. The technic 

 consists in sterilizing the skin with a pledget of cotton 

 and alcohol overlying the insertion of the deltoid 

 muscle or elsewhere on the body, as described on page 

 178. It is recommended whenever possible to inoc- 

 ulate on the distal side of the lesion, thereby giving the 

 patient the immediate benefit of the antibody forma- 

 tion through the local lymph system in addition to 

 the subsequent effect to be obtained through the blood- 



