CHAPTEE XII. 



THE "STRUCTURE" OF TOXINS AND ANTITOXINS 

 AND THE NATURE OF THE TOXIN-ANTI- 

 TOXIN REACTION. 



Because of the impossibility of obtaining bac- Biologic 



,.-,,.. / ,. 1 Analysis. 



term! toxins in pure form, no conception can be 

 gained of their composition in terms of atoms or 

 molecules, although it must be assumed that they 

 have some unknown molecular structure. Infer- 

 ences as to their nature and structure can be 

 gained only by means of the biologic experiment, 

 i. e. } their effects on animals and animal cells 

 under arbitrary conditions. 



When a toxin and its antitoxin are mixed in Neutraiiza- 



. . . , . . . . tion of Toxin 



suitable proportions, the mixture becomes non- by Antitoxin. 

 toxic as the result of chemical union of the two 

 substances; each molecule of toxin has combined 

 with a molecule of antitoxin to form a new non- 

 toxic molecule which may be spoken of as the 

 toxin-antitoxin molecule. It was at one time sup- 

 posed that antitoxin had the power of destroying 

 the toxin, perhaps by a ferment-like action. In 

 two instances it has been possible to show that 

 this is not the case. Ordinarily toxins are more 

 susceptible to heat than antitoxins, but in the case 

 of pyocyaneus toxin and snake venom the anti- 

 toxins are the more susceptible. Wassermann 

 found that when a neutral mixture of pyocyaneus 

 toxin and its antitoxin was heated to a certain 

 temperature the mixture again became toxic, and 

 Calmette made a similar observation concerning 

 venom and antivenin. If the toxin had been de- 



