504 COLLECTED STUDIES IN IMMUNITY 



the toxons. According to them the long-drawn-out toxon zones are 

 the expression of the incomplete combination of toxin and antitoxin, 

 the neutralization of which they believe follows the ammonia-boric 

 acid type. There are, however, a number of weighty reasons why 

 this view cannot be accepted. 



It was but natural at first to ascribe the toxon stage to phenomena 

 such as Arrhenius and Madsen now have in view. It had already 

 been noticed by others that often a considerable interval exists be- 

 tween L-f- and L . Knorr, in referring to this, had spoken of "un- 

 neutralized poison residue." The assumption, however, that we are 

 here dealing with the result of an incomplete neutralization is con- 

 troverted by the analysis of a poison which I encountered during the 

 course of my investigations. This was Poison No. 10 (of my series), 

 whose L and L-j- values were very close together. L contained 27.5 

 and L-j- 29.2 L. D. Hence D = 1.7 L. D., which is a close approach to 

 the figure demanded by a simple diphtheria poison. 



The following considerations will show that this value, 1.7. should be cor- 

 rected so as to be still lower. The original calculations were based on my earlier 

 assumption that toxins and toxoids are uniformly mixed. This however, has 

 been superseded by the spectrum method of representing the neutralization of 

 poisons. Experience has taught us that such deteriorated poisons usually 

 consist of a small zone of hemitoxin and a more or less pronounced zone of 

 tritotoxin-toxoid, in which as a rule nine toxoid equivalents fall on one toxin 

 equivalent. Several times I have observed tritotoxin-toxoid zones containing 

 */, toxin, and Madsen also has described such a poison. As can be seen from 

 our calculations given above, the theoretical change from L , to Lf is influenced 

 solely by the tritotoxoid zone. If we therefore assume that our poison pos- 

 sessed a tritototoxin-toxoid portion whose strength was Vu, ( an d this is extremely 

 probable) we shall find that by a little calculation that the poison probably 

 contained no toxon whatever. Very likely the tritotoxoid zone reached to 

 the end (200) of the spectrum. On the assumption of a '/,o tritotoxin-toxoid, 

 if we multiply L by 210 / 20U we shall obtain Lf = 28.9 L. D. This agrees very 

 well with the figures obtained experimentally, Lf=29.2 L. D. 



We may therefore very well assume that we were dealing with a 

 poison free from toxon or one which contained only very small traces 

 of toxon. 



This fact is hard to reconcile with the theory of Arrhenius and 

 Madsen, for if toxin and antitoxin neutralized each other like 

 ammonia and boric acid, all poisons should show a long zone of in 

 complete neutralization. 



The independent existence of the toxons is further corroborated 

 by the fact that the toxon zone varies enormously in different sped- 



