SMALL POX 663 



closely approximated vesicles in a dilution of 1 in 500, and numerous 

 isolated vesicles in a dilution as high as 1 in 1,000. 



Quantitative estimations of the bacteria in the glycerinated virus 

 should be made by the plating method and the vaccine used only when 

 after several weeks of preservation the numbers of the bacteria have 

 been greatly diminished. In glycerinated pulp the bacteria will' often 

 disappear entirely in the course of a month. The vaccine should also 

 be tested for the possible presence of tetanus bacilli, by the inoculation 

 of white mice. 1 



Vaccination of human beings is performed by slightly scarifying the 

 skin of the arm or leg with a sharp sterile needle or lancet and rubbing 

 into the lesion potent vaccine virus. The virus was formerly dried upon 

 wood, bone, or ivory slips and moistened with sterile water before the 

 operation. At the present day the glycerinated pulp is almost univer- 

 sally employed. 



That vaccination is of incalculable benefit to the human race is no 

 longer a question of opinion, and opposition to the practice is explicable 

 only on the basis of ignorance. Statistical compilations upon this point 

 are very numerous. It may suffice to select from the voluminous 

 literature a single example, taken from Jiirgensen, which embodies the 

 statistics of death from smallpox in Sweden, during the periods immedi- 

 ately preceding and following the introduction of vaccination. In that 

 country the first vaccination was done in 1801. By 1810 the practice 

 was generally in use but not enforced. In 1816 it was legally enforced. 

 The years from 1774 to 1855 can thus be divided into three periods. 



1. Prevaccinal period, 1774-1801 (25 years). Deaths smallpox per 



million inhabitants 2,050 



2. Transitional period, 1801-1810 (9 years) 680 



3. Vaccination enforced, 1810-1855 (35 years) 169 



Prevaccinal period death rate 20.00 per mille. 

 Vaccinal period death rate 0.17 per mille. 



In considering the benefit of vaccination it must not be forgotten 

 that revaccination is quite as important as the first vaccination, which 

 confers immunity only for from seven to ten years. A child should there- 

 fore be vaccinated soon after birth or at least before the eighth month, 

 and the process should be repeated every seven years thereafter. 



1 Paul, loc. cit. 



