RELATION OF TOXIN ES TO ANTITOXINES. 39 



In certain toxine solutions, however, there may be relatively 

 more or less toxones, so that L , even in the case of fresh pre- 

 parations, may sometimes be greater or smaller than 100. At 

 the same time, secondary derivatives, toxoids, formed from the 

 true toxine are produced in all toxine solutions on keeping, and 

 these invariably lower the value of L . 



We must reserve until afterwards a fuller discussion of the 

 mode in which toxines are converted into toxoids, and, above all, 

 of the quantitative relationships of this conversion. Here we 

 have next to deal with the significance of the limitation value 

 L + . Whilst the toxoids formed as secondary products have a 

 decided influence upon the amount of the L dose, they are 

 absolutely without influence upon the value L + (and, therefore, 

 also upon D), as has been shown by EHRLICH. 



Now there are, a priori, three conceivable kinds of toxoids : 

 Firstly, those that possess a greater affinity than the toxine for 

 the antitoxine, which combine with it sooner, and are, under 

 certain conditions, capable of dissolving existing combinations 

 between toxine and antitoxine in their own favour. These are 

 the protoxoids. 



A second category consists of the syntoxoids, which have the 

 same affinity as the toxine for the antitoxine, and thus have no 

 influence upon the combination of toxine with antitoxine, just as 

 their own combinations with the antitoxine are not affected by 

 the toxine. Lastly, there remain the epitoxoids, which have a 

 weaker affinity than the toxine for the antitoxine, and can be 

 liberated again by the toxine from their combination with the 

 antitoxine. Such epitoxoids occur, as EHRLICH was able to 

 demonstrate, not as secondary products, but are already present 

 in the fresh toxine solutions ; they are identical with the toxones 

 mentioned above. 



This consideration leads us to the following points of view as 

 regards the influence of toxoids and toxones upon the value of L + 

 or D: 



The toxoids formed as secondary products viz., pro- and 

 syntoxoids have no influence at all upon L + , as can very easily 

 be demonstrated. 



Assuming that we have a neutral mixture of antitoxine with 

 toxine and protoxoid, we can represent this condition of 

 equilibrium graphically by means of the equation 



90 Toxine- Antitoxine +10 Protoxoid- Antitoxine 

 = Physiological Neutrality (L ). 



Additional quantities of the same poison are now added in order 



