ON THE ANTITOXINS OF DIPHTHERIA. 205 



sequelae of the disease, which, as is well known, do not in 

 any way improve on giving antitoxic serum. It is im- 

 possible to doubt from this short resume that Behring 

 still holds that an essential destruction of toxin results 

 from an accumulation of antitoxin in the body, and in the 

 case of diphtheria the crucial experiment to decide this 

 point is wanting, since at the present time it is impossible 

 to separate the toxin and antitoxin which occur in one 

 fluid. Both these bodies we recognise by their effects ; 

 by no other means can their identity be established. Allow- 

 ing that they may be proteid in nature, a knowledge of 

 them will only be possible when more extended information 

 has been gained of the nature and constitution of proteids. 



Since Behring's discovery it has been established that 

 the serum of immunised animals is prophylactic and curative 

 for many other diseases besides diphtheria. For many in- 

 fective maladies, among which pneumonia, cholera, typhoid, 

 hog-cholera may be mentioned, this has been abundantly 

 proved by the researches of F. and G. Klemperer, Issaef, 

 Pfeiffer, Sanarelli and Metchnikoff, while a recent research 

 by Viquerat appears to show that patients suffering from acute 

 suppuration, associated with pyogenic bacteria, may yield a 

 serum which is curative when injected in the neighbourhood 

 of abscesses (38). The universal application of Behring's 

 theory of antitoxins is, however, limited, since in tetanus 

 and diphtheria the toxins of bacilli are neutralised or 

 destroyed, but in other diseases the serum protects not 

 against infection with toxins, but against infection with 

 living bacteria. In this case it is possible that the cells 

 of the organism, even if they do not ingest and destroy the 

 invading microbes, as Metchnikoff affirms, are roused or 

 stimulated so as to oppose the spread of infective micro- 

 organisms or the products of these throughout the body. 

 In the case of protection against diphtheria the antitoxin 

 which appears is therefore to be looked upon as the product 

 of living cells, or as a metabolite occurring under special 

 conditions, one of which may be the stimulation of the 

 cell by the toxin. That antitoxins are products of living 

 cells may possibly be inferred from the observation of F. 



