CHEMICAL EQUILIBRIA 123 



observed with inorganic poisons. But Ehrlich 

 concluded that the diphtheric poison contains a 

 substance, called epitoxoid or toxon, which has a 

 less avidity for the antidiphtheric serum than the 

 chief poison, the toxin, and therefore remains un- 

 neutralized, after the toxin has been made innocuous. 

 Madsen and Dreyer have pointed to the absence 

 of these " toxons " in some of his diphtheria poisons. 

 After all we should not accept their existence without 

 more convincing proofs. 



In his investigation of the diphtheria poison 

 mentioned on p. 1 1 1 Madsen observed that it was 

 only half as violent in September 1903 as in February 

 1902. The poison had lost half its toxicity during 

 the lapse of nineteen months, but still it neutralized 

 the same quantity of antitoxin and the dissociation 

 constant had remained unchanged. Similar obser- 

 vations had been made before by Ehrlich. In 

 order to explain this peculiarity it seems necessary 

 to suppose that the half number of the molecules of 

 the poison had been transformed in an innocuous 

 modification, which retained the properties of the 

 poison in regard to the antitoxin. Such an in- 

 nocuous substance may be called " syntoxoid ' in 

 accordance with Ehrlich's nomenclature. 



Quite recently Calmette and Massol described 

 a cobra poison (Comptes Rendus, 159, 152, Paris, 1914), 

 which had lost five-sixths of its toxicity from 1907 

 till 191 3 and still retained its property of binding 

 the specific antivenin un weakened. It had been 

 kept in darkness and in a closed tube. Powdered 



