CHAPTER IV 



INTERREACTIONS OF TOXIN AND ANTITOXIN 



STARTING from the facts that a suitable dose of antitoxin will 

 prevent the development of symptoms if toxin is injected shortly 

 before, at the same time, or shortly after, or that if antitoxin and 

 toxin be mixed in vitro and injected subsequently, no symptoms 

 develop, we have to inquire the mechanism by which this is brought 

 about. Two theories suggest themselves at once. The antitoxin 

 might act on the cells of the living body in such a way as to render 

 them insusceptible to the action of the poison, or, in other words, 

 render them immune, or the toxin and antitoxin might unite 

 chemically to form an inert and harmless compound. When the 

 fundamental facts of antitoxic action were first discovered, the 

 majority of pathologists probably inclined to the former alternative, 

 the latter seeming too simple and teleological. A certain amount 

 of experimental evidence was also forthcoming in favour of this 

 view, but as this has a merely historical value it will not be 

 considered. It is now fully proved that toxin and antitoxin form 

 chemical compounds, and that the prophylactic and curative value 

 of the latter is to be explained simply on the grounds that this 

 compound is inert, or devoid of toxic action on the animal cells. 

 The evidence in favour of the occurrence of this chemical com- 

 bination requires brief discussion. 



The first group of experiments pointing in this direction are 

 those in which the toxin and antitoxin are mixed in vitro, and 

 the result tested by means of red blood-corpuscles as indicators, 

 the intervention of the cells of the living body being thus excluded. 

 (Many of these experiments can be repeated on corpuscles which 

 have been heated to a temperature sufficient to destroy the life of 

 isolated body cells, and the possible objection that the corpuscles 

 are " surviving " thus removed.) 



The first of these researches was that of Ehrlich, who showed 



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