THE BACTERIA (SCHIZOMYCETES) 173 



immunity is greatly increased. First into tlie animal's body 

 there is injected a small amount of toxin. This process is 

 repeated, with an increasing amount, at intervals of a week 

 or a little less, for a period of two or three months. The ani- 

 mal finally withstands, with no ill consequences, an amount 

 of toxin that would have proved fatal if used at first. At this 

 time some of the blood is drawn off, allowed to clot, and the 

 antitoxic serum is sterilized. After its relative strength is 

 determined, it is sealed in small bottles and is ready for dis- 

 tribution. A human being who has diphtheria may then be 

 given the proper amount of antitoxin. If it is properly given, 

 and given early enough, the attack is defeated.^ 



Great benefits have come to the human race through the 

 discovery of diphtheria antitoxin. It was generally introduced 

 in 1894. A study of the following table, containing data for 

 ten years before and ten years after the introduction of anti- 

 toxin, will give an idea of the value of this scientific discovery. 



AVERAGE ANNUAL DEATH RATE FROM DIPHTHERIA 

 PEK 10,000 POPULATION 2 



Before Use of Antitoxin 

 Antitoxin Period 



(1885-1894) (1895-190i) 



Paris 6.41 . . . 1.49 



Berlin . ... .... 9.93 . . 2.95 



Vienna 8.14 2.9.5 



London 4.85 . . . 3.88 



New York . 15.19 . . . 6.62 



Boston . . 11.76 . . . 6.34 



Baltimore 7.34 . . . 4.99 



Chicago^ 14.29 . . . 5.13 



An estimate of the number of lives saved annually in New 

 York and Chicago will further illustrate the benefits from the 

 use of antitoxin. 



1 Certain disastrous cases where impure antitoxin was used, resulting in 

 infecting patients witli other disease germs, are inexcusable. These oases, 

 however, should not lead people to decline to use antitoxin. 



2 Jordan, E. 0., General Bacteriology, 1908. 



8 Use of antitoxin begun in 1895-1896 ; drop from 12.01 (1895) to 7.62 (1896). 



