PAPERS OX MEDICINE AND PUBLIC HEALTH 465 



teutial possibilities for the prevention of a serious di- 

 sease than the elaboration of the toxin-antitoxin mixtures 

 for the prevention of diphtheria. 



While Behring christened the mixtures which he used 

 with the name TA and was the first to employ them for 

 immunization in humankind, he was in no wise the first to 

 suggest their use. Apparently Behring 's TA mixtures 

 were born with teeth and fully armed to fight diphtheria, 

 for nowhere does he state how and when he conceived the 

 idea nor does he give the relative proportions of the toxin 

 and antitoxin in his mixtures. The evolution of a great 

 discovery is usually a tortuous record of bhmders, stumb- 

 ling, infinite patience and industry, keen observation, 

 half-baked conclusions and fearlessness in breaking away 

 from traditional lines of thought. This is the history 

 as I see it of the development of the TA mixture. Of 

 those who contributed to the solution of the mystery of 

 active immunization in diphtheria, one name so far out- 

 distances all others that what I shall say is taken largely 

 from his reports. That name is Theobald Smith, 



The first step toward active immunization against 

 diphtheria was made in 1895, when Wernicke reported 

 that the oft" spring of the guinea pigs which had previously 

 been treated with toxin and antitoxin possessed increased 

 resistance to diphtheria toxin. He also showed that the 

 male parent guinea pig in no way influenced the immun- 

 ity of the young. These important obsen^ations passed 

 unnoticed for a number of years. In 1902, Park im- 

 munized horses, goats and guinea pigs by mixtures of 

 diphtheria toxin and antitoxin. As a matter of fact, he 

 and others had actively immunized horses long before 

 this, because in the treatment of horses to be bled for 

 furnishing diphtheria antitoxin they had almost from the 

 first learned that by injecting antitoxin with initial dose 

 of toxin, stronger doses of toxin could be used, resulting 

 in a greater and more rapid formation of antitoxin in the 

 animal's blood. 



None at this time seemed to realize the possibilities 

 of all they were doing. They were interested only in the 

 commercial production of a potent antitoxin. 



