NEUTRALISATION OF SIMPLE POISONS 



197 



sen concluded in agreement with Ehrlich l that a frac- 

 tion of the antitoxin-binding substance is not poisonous, 

 and that it binds antitoxin before the toxin itself. Such a 

 substance is called prototoxoid by Ehrlich. As the quan- 

 tity, n, necessary to determine a decrease of the toxicity 

 is greater with the old than with the fresh poison, the con- 

 clusion was drawn that the quantity of prototoxoid in- 

 creases with time, and perhaps as the preparation was 

 quite fresh it may at first have contained no prototoxoid 

 at all. 



This was in complete agreement with Ehrlich's ideas, 

 but on another point regarding the existence of so-called 

 toxons or epitoxins Madsen differed from Ehrlich. As will 

 be seen from the preceding table, the phenomenon of Ehr- 

 lich is very prominent, the same quantity of antitoxin pro- 

 ducing a much less marked reduction of the toxicity at the 

 beginning of the neutralisation than later on. This is 

 explained by the chemical equilibrium between toxin and 



1 Ehrlich: Deutsche med. Wochenschrift, No. 38 (1898); Aug. 31, Sept. 7 

 and 14 (1903). 



