IX. 



DIPHTHERIA 



IT is just twenty years since Roux, in September, 

 1894, at the Congress of Hygiene and Demography 

 in Buda-Pesth, spread the good news of the dis- 

 covery of diphtheria-antitoxin. It was in Septem- 

 ber, 1895, that Pasteur, dying at Villeneuve, had 

 round him the whole scene of the making of the 

 antitoxin : every day, it was saving children from 

 death. 



Klebs, in 1875, had discovered the germs of the 

 disease : and Loeffler, in 1882, obtained them in 

 pure culture. They are therefore called the Klebs- 

 Loeffler bacillus. Roux and Yersin, in 1888-90, 

 proved that the toxin, the product of the germs, 

 could be separated, by filtration, from the germs : 

 and this toxin, though it contained no germs, 

 would none the less produce, in animals, the effects 

 of the disease itself. By December, 1890, Behring 

 and Kitasato were able, with graduated doses of 

 this toxin, to immunise animals against diphtheria : 



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