40 IMMUNE SERA 



pieces are stained deeply, and the last find no color 

 left. In the same way, on adding toxin to antitoxin 

 in divided doses, the last portions of the poison 

 cannot be neutralized, as the first are supersatu- 

 rated with antitoxin. When the entire mixture 

 is made at once, on the contrary, the antitoxin is 

 spread all over the toxin molecules and a complex 

 is obtained which contains an even proportion of 

 the antidote, and which, consequently, is not as 

 fatal as even a small dose of free toxin. The action 

 which Ehrlich therefore ascribes to toxons, Bordet 

 refers to toxin which is partially saturated with 

 antitoxin. Bordet also cites the researches of 

 Grassberger and Schattenfroh on the toxin of 

 symptomatic anthrax. The toxic fluid which these 

 authors employed contains only a single poison: 

 there is no reason for assuming the existence of 

 toxoids, inasmuch as the toxic power of the poison 

 is constantly parallel to its neutralizing power for 

 antitoxin. On mixing a certain dose of the toxin 

 either with little or with much antitoxin, complexes 

 of toxin-antitoxin were obtained which varied 

 in their reaction to heat. Moreover, these authors 

 found that their poison absorbs much more anti- 

 toxin than is necessary to destroy its entire toxicity,. 

 and forms a stable compound with it. Bordet's con- 

 ception of the toxin-antitoxin reaction thus seems 

 to be very simple. The main difficulty which it 

 encounters is the strict specificity of the combi- 



