THE CONQUEST OF DISEASE 



ence in five different homes left a trail of 

 twenty cases of diphtheria behind her and five 

 deaths. Soon after the discoveries of Klebs 

 and Loeffler, many of these apparently healthy 

 bacteria carriers were reported. Now cultures 

 are taken from the throats of convalescents, 

 and the period of danger is positively deter- 

 mined. 



Roux, working in the Pasteur Institute in 

 Paris, found that in the cultures of diphtheria 

 bacilli there was produced a virulent poison. 

 He filtered this out of the cultures, and, guided 

 by the experiences of Pasteur, sought to im- 

 munize animals by injecting a small amount of 

 this toxin into their blood. Behring carried on 

 studies in the same direction, beginning with 

 small doses of the toxin and gradually increas- 

 ing it until the animals became immune and 

 could not be inoculated with diphtheria. A 

 small amount of serum from the blood of ani- 

 mals thus immunized, when injected into 

 another animal had the power of rendering it 

 immune for several weeks. Then the serum 

 was used in children, suffering with diphtheria, 

 and good results were observed. Since that it 

 has been found that the horse lends itself best 

 for producing the antitoxin in large amounts. 



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