TOXINS AND ANTITOXINS 139 



tetanus toxin, or conversely. This means that diphtheria toxin 

 is attached to chemical groups of the body cells (receptors) 

 which are quite different from the groups to which tetanus 

 toxin unites, and hence different receptors are thrown out in 

 immunizing against each. 



The neutralization of toxin by antitoxin is distinctly a chemi- 

 cal process, which occurs as well in the test-tube as in the body. 

 It occurs according to the laws of definite proportion, a given 

 amount of antitoxin neutralizing a proportionate amount of 

 toxin under equal conditions (hence the toxin is not destroyed 

 by antitoxin through a ferment action, as was at first suggested). 

 Neither the toxin nor the antitoxin is destroyed in the process 

 of neutralization, as has been proved by suitable experiments, 

 but they appear to be chemically united to each other, as any 

 two large molecules may be. Neutralization occurs more 

 rapidly under the influence of warmth, and more slowly in the 

 cold; and it is more rapid in concentrated than in dilute solu- 

 tions, just as with ordinary chemical reactions. According to 

 Arrhenius and Madsen, the reaction of antitoxin upon toxin is 

 accompanied by the liberation of much heat 6600 cal. per 

 gram molecule, or about half as much as is set free by the action 

 of a strong acid upon a strong base. 1 On dilution of a neutral 

 toxin-antitoxin mixture, a certain amount of dissociation seems 

 to occur. 2 



There is no relation between antitoxins and enzymes. The 

 antitoxin acts quantitatively, and produces no detectable altera- 

 tion in the toxin, or in any other substance, as far as we know. 

 It also has but one functionating group (haptophore), the one 

 with which it combines with the toxin ; whereas both toxins 

 and enzymes seem to have two functionating groups, one which 

 unites with the cell or substance that is to be attacked, the other 

 which produces the chemical changes. 



CHEMICAL NATURE OF ANTITOXINS 



This is as entirely unknown as is the nature of the toxins. 

 Investigation of antitoxic serum (principally diphtheria anti- 

 toxin) has shown that the antitoxic properties are closely related 

 to the serum globulin, which, however, by no means proves 

 that antitoxin is serum globulin or any other sort of a proteid. 

 According to Ehrlich's theory, antitoxin consists of free cell 

 receptors, and these receptors are presumably simple chemical 



1 Literature of chemical and physical reactions of toxin and antitoxin given 

 by Zangger, Cent. f. Bakt. (ref.), 1905 (36), 238. 



2 See Otto and Sachs, Zeit. exp. Path. u. Ther., 1906 (3), 19. 



