VACCINES IN PROPHYLAXIS OF DISEASE 185 



used, and the site of vaccination should be clean. 

 In preparing the site of inoculation, use soap 

 and water and dry with a clean towel. Ether or 

 alcohol may be used, if allowed to evaporate be- 

 fore proceeding with the 

 operation ; otherwise 

 the antiseptic may 

 easily destroy the life of 

 the virus. A single 

 linear scratch about y s 

 of an inch long should 

 be made with a sterile 

 needle ; the scratch 

 should not penetrate the 

 subcutaneous tissue, 



for, if bleeding occurs, virus rubbed into such 

 an incised area will be washed away by the 

 blood. Small scratches have the advantage of 

 healing rapidly and of presenting less dan- 

 ger of secondary infections. Avoid scarifica- 

 tions or cross-scratching, as this method pro- 

 duces an abraded surface which is soon covered 

 by a crust of serum and blood, leaving a cen- 

 tral irritated wound which invites infection. 



With the ivory point or wooden stick rub the 

 virus gently but thoroughly into the scratch, re- 



single linear scratch 

 about % inch long, ex- 

 tending down to the 

 corium but not deep 

 enough to cause bleed- 

 ing; ready to be inocu- 

 lated with Vaccine Virus. 



