492 COLLECTED STUDIES IN IMMUNITY. 



self to a single mixture, but analyzes a great many different mixtures 

 in which the relation of toxin-alkaloid and toxoid-alkaloid varies. 1 



It is all the more surprising that in the analysis of the constitu- 

 tion of poisons Arrhenius and Madsen have not studied the question 

 from this point of view because they do not at all neglect the exist- 

 ence of toxoids. Apparently this is because of a slight misunder- 

 standing, for these authors proceed exclusively on the assumption that 

 in toxoids one is dealing with protoxoids, i.e., with toxoids which 

 possess a higher affinity for the antitoxin than does the toxin. In 

 fact, one can easily observe that the formation of prototoxoids affects 

 the end point of the titration but little. This I had predicted in my 

 first study on the evaluation of diphtheria serum. Let us assume, 

 for example, that a mixture of 1 equivalent hydrochloric acid (proto- 

 toxoid) and 3 equivalents prussic acid (toxin) is neutralized by a 

 strong base. In that case the hydrochloric acid will be neutralized 

 first, after which the neutralization of the prussic acid will proceed 

 very much the same as though only prussic acid were present. 



We must now see whether diphtheria poisons, such as I have 

 investigated, contain other toxoids besides prototoxoids. The ma- 

 terial at hand makes the decision of this point very simple. In four 

 poisons containing a prototoxoid zone (of which two were published 

 by myself and two by Madsen) 1 have calculated the relation of proto- 

 toxoid and toxoid to toxin. In doing this I have regarded exclusively 

 the L t dose, and so eliminated the toxons which would otherwise still 

 more increase the toxoid figure. 



1 In the very simple example of two alkaloids just mentioned two determina- 

 tions of different mixtures would permit the calculation. In my opinion no 

 definite conclusions as to the constants of the toxin can be drawn from the 

 analysis of one particular toxin containing toxoid. Arrhenius and Madsen 

 analyzed two different tetanus poisons, one of which had undergone toxoid 

 modifications through years ot preservation as a dry substance, while the other 

 had suffered similar modifications through several days' standing of the solu- 

 tion. The authors calculated from their experiments that in the one case the 

 constant of dissociation had been increased 50%, in the other ten times. In 

 view of what has just been stated this calculation, which leaves out of account 

 the presence of toxoids, cannot be regarded as conclusive. The divergence of 

 the constants could easily be due exclusively to the presence of toxoids, and 

 these, in view of the different methods by which the poisons were attenuated, 

 could be different in the two cases. I may also add that in the toxoid for- 

 mation of diphtheria toxins I am convinced that the toxin groups which 

 remain do not suffer any change in their affinity. 



