512 COLLECTED STUDIES IN IMMUNITY. 



1. The diphtheria bacillus produces several kinds of poisons, 

 especially toxins and toxons. 



2. The affinity of diphtheria toxin to the antitoxin is very great. 



3. The deviations from a straight line as they manifest themselves 

 in the graphic representation of the neutralization of the poison 

 cannot be explained by the assumption of a single poison possessing 

 a weak affinity. They are rather the expression of the fact that the 

 poison bouillon contains admixtures of various kinds of substances 

 of a toxoid character. 



4. The varied affinity of the toxoids cannot be explained by the 

 assumption that a simple toxin when transformed into toxoid suffers 

 a change in affinity either positively or negatively. Rather does 

 this indicate that the toxic bouillon contains, preformed, various 

 toxins of different affinities. 



5. There is no change in the haptophore group in the formation 

 of toxoid. 



6. The absolute number of combining units contained in the 

 immune unit or in the L dose of poison is 200. 1 



I have finished. If the results of the first encounter of two such 

 different methods of study as the mathematico-physical and the bio- 

 logical have not shown complete agreement we should not be at all 

 .surprised. The natural aim of physical chemistry must always be 



1 Bordet has recently attempted to explain the toxon phenomena by the 

 assumption that the toxin molecule can combine with antitoxin in varying 

 proportions. One would accordingly have to assume that the toxin molecule 

 contains several haptophore groups. The complete occupation of these groups 

 causes the toxicity to be entirely lost, whereas partial saturation causes a de- 

 crease in toxicity. That is to say, amounts of antitoxin which do not com- 

 pletely neutralize the toxin would weaken it in such fashion that it would exert 

 a different action. It is strange that so eminent an investigator as Bordet 

 should not have attempted to convince himself of the correctness of this hy- 

 pothesis by means of the experiment. He would then have found that the 

 facts are irreconcilable with such an assumption. We have shown at great 

 length that the toxon actions are nothing less than constant phenomena and 

 have called attention to the great extent of the quantitative variations (0-300). 

 If one were to follow Bordet it would then be necessary to assume an enormous 

 multiplicity of haptophore groups in the toxin molecules, and this would lead 

 to a hypothesis far more complicated than mine, although the latter harmo- 

 nizes all the experimental results. In support of his conception Bordet refers 

 to experiments with complement and anticomplement. I must say, however, 

 that in these we are dealing with such complicated relations that it is not per- 

 missible to apply the conclusions drawn from them to the far simpler relations 

 existing between toxin and antitoxin. 



