132 INFECTION AND RESISTANCE 



made, each successive one possesses progressively less relative neu- 

 tralizing power than the preceding. 



This, it is plain, is closely analogous to the phenomena observed 

 by Ehrlich in his "Partial Absorption" method, and Arrhenius con- 

 cludes that the two phenomena, toxin-antitoxin and boric acid-am- 

 monia neutralization, are closely analogous. His point of view is 

 further strengthened by his experiments with tetanolysin and its 

 specific antibody, in which he constructed a curve similar to that 

 given for boric acid, derived a formula and found that the observed 

 and the calculated values closely coincided for various mixtures of the 

 two. He claims, in consequence, that the phenomena observed by 

 Ehrlich should not be interpreted as due to "partial toxins" toxoids 

 or toxons, but dependent rather upon the presence of varying quan- 

 tities of free toxin dissociated from union with antitoxin because of 

 the reversibility of the union. 



The opinions of Arrhenius and Madsen are not generally ac- 

 cepted. It is in the first place doubtful whether substances like toxin 

 and antitoxin, which, as far as we know their chemical nature at all, 

 belong to the class of substances spoken of as colloids, can be re- 

 garded as subject to the laws of Mass Action in their reactions. 



Nernst 22 has criticized Arrhenius' deductions chiefly on the 

 basis of their assumption of the reversibility of the union of toxin 

 and antitoxin, since reversible reactions between colloids, though not 

 at all inconceivable, have so far not been definitely shown. Further- 

 more, as Nernst states, if complete reversibility of such reactions 

 were possible it would be hard to understand how antitoxin can pro- 

 tect the animal against the actions of toxin. 



Another point of view concerning the toxin-antitoxin union which 

 has been gaining ground especially through the work of Landsteiner 

 and his pupils, is that of Bordet. 23 Bordet expresses his views in 

 the following way: 



I. When one mixes with a certain quantity of toxin an amount 

 of antitoxin which is insufficient to produce a complete neutraliza- 

 tion, the molecules of antitoxin are not taken up by a definite frac- 

 tion of the toxin molecules, satisfying the affinities of these entirely 

 while other units remain intact ; on the contrary, the antitoxin mole- 

 cules distribute themselves equally upon all the toxin molecules pres- 

 ent, and these are therefore, all of them, partially saturated, and 

 lose proportionately a part of their initial toxicity. One could say 

 that there is an attenuation of the toxin since there is a formation of 

 a less poisonous complex. 



II. The symptoms of poisoning produced by such a complex in- 

 jected into animals or placed in contact with sensitive cells cannot be 



22 Cited from Landsteiner in "Kolle u. Wassermann Handbuch," 2d Ed., 

 Vol. 5. 



23 Bordet. Ann. de I'Inst. Past., Vol. 17, 1903. 



