224 ANTITOXINS 



placed a label on each package of antitoxin, bearing a date beyond which 

 the serum is not guaranteed to contain the amount of antitoxin present 

 at the time it was put up. 



The antitoxins, with few exceptions, are far more stable than the 

 toxins, resisting heating up to 62 C., but gradually deteriorating with 

 higher temperatures. Boiling destroys them completely. They are 

 readily preserved with small amounts of chloroform, phenol, tricresol, 

 etc., although strong solutions of these produce destructive changes. 

 Putrefaction of the serum destroys the antitoxin content. Ehrlich has 

 devised the best method for their preservation, which consists in drying the 

 serum in vacuo and preserving it in the dark, at a low temperature, in the 

 presence of anhydrous phosphoric acid. So preserved, antitoxin retains 

 its strength for prolonged periods and is used in standardizing toxins. 



Natural Antitoxins. The appearance of so-called natural antitoxins 

 can be explained on the basis of Ehrlich's theory. Since the antitoxin 

 is composed of receptors that are not new bodies, but simply normal 

 receptors produced in excess, it is reasonable to assume that a few may 

 be thrown off occasionally, constituting the natural antitoxin. 



Small amounts of natural diphtheria antitoxin may be found in cer- 

 tain individuals and lower animals. Since the diphtheria bacillus is 

 so wide-spread in its distribution, it is possible that minor subinfections 

 may be responsible for antitoxin production, and this is probably always 

 the case when large amounts are found. 



Information regarding natural antitoxins for other members of the 

 toxin-producing group of microorganisms is less complete, although it 

 is highly probable that natural antitoxins for these exist. 



Specificity of Antitoxins. Antitoxins well illustrate the law of 

 specificity that exists between antigen and antibody, since they are 

 strictly specific for their toxins. Diphtheria antitoxin will neutralize 

 only diphtheria toxin; tetanus antitoxin, only tetanus toxin, and so on 

 through the list. This specificity is not confined to the particular 

 toxin-producing organism that generates the antitoxin; for example, 

 there are various kinds of diphtheria bacilli, differing as regards 

 morphology and toxicity, although one antitoxin appears to act the same 

 with their various toxins. 



Nature of the Toxin- Antitoxin Reaction. While the injection of toxin- 

 antitoxin mixtures into the lower animals is the only practical method 

 of testing and standardizing the curative and prophylactic powers of 

 their serums, this method does not throw much light upon the nature of 

 the toxin-antitoxin reaction, or show how antitoxin overcomes the toxin. 



