Artificial immunity against toxins 349 



This method of immunisation by mixtures of toxin and antitoxin 

 is often spoken of as the method of vaccination by toxones. This 

 name, "toxone," was first applied by Ehrlich 1 to a product developed 

 by the diphtheria bacillus in culture media, a product less and 

 differently toxic than is the true diphtheria toxin, yet capable of 

 neutralising antitoxin. The idea of toxones presented itself to 

 Ehrlich in connection with a fundamental fact noted by him, namely, 

 that when to a non-toxic mixture of diphtheria toxin and antitoxin 

 there is added one and even several lethal doses of the former, the 

 animal is not affected. To make it succumb to intoxication it is 

 sometimes necessary to add more than 20 lethal doses of toxin. To 

 explain this paradoxical result, Ehrlich formulated the hypothesis 

 that, in the soluble products of the diphtheria bacillus there exist 

 two poisons : (1) the true toxin which exhibits a very strong affinity 

 for antitoxin, and (2) the toxone which possesses less avidity for this 

 antibody. When to an inactive mixture of the products of diphtheria 

 bacilli and of antitoxin, there is added a fresh quantity of these same 

 products, the added toxin, owing to its greater affinity, replaces the 

 toxone of the previous combination. In the mixture to which is 

 added one or several lethal doses of diphtheria poison, the toxone [367] 

 only is found free, all the toxin being combined w r ith the antitoxin, 

 and, as the toxone is only feebly toxic, the animal resists without 

 suffering any serious illness. 



Madsen 2 adopted the theory of the diphtheria toxone, and affirmed 

 that this substance poisons but slowly, produces neither early nervous 

 symptoms nor loss of hair, but excites slight oedema at the point of 

 inoculation and late paralyses. Susceptible animals may olie from 

 toxones, but very much later than as the result of poisoning by the 

 toxins. 



Ehrlich's pupils have extended the theory of toxones to other 

 bacterial poisons. Thus Madsen 3 has described a similar toxone in 

 tetanus poison the tetanolysin of Ehrlich which dissolves the red 

 blood corpuscles, and Neisser and Wechsberg 4 refer to a toxone in 

 the poison produced by the staphylococcus. 



Ehrlich also describes toxoids as occurring in diphtheria poison. 

 The toxone, he maintains, is a product of the diphtheria bacillus 



1 Deutsche med. Wchnschr., Leipzig, 1898, S. 597. 



2 Ztschr.f. Hyg., Leipzig, 1897, Bd. xxiv, S. 425. 



3 Ann. de Flnst. Pasteur, Paris, 1899, t xra, pp. 568, 801. 



4 Ztschr.f. Hyg., Leipzig, 1901, Bd. xxxvi, S. 325. 



