NEUTRALISATION OF H^MOLYSINS 1/7 



spectively). The next equivalent of boracic acid added has 

 an effect which equals only about the fifth part of that of 

 the first equivalent. 



This behaviour is to a high degree similar to that termed 

 Ehrlich's phenomenon, observed in the neutralisation of a 

 toxin with its antitoxin. The first part of the antitoxin 

 added neutralises, generally speaking, a greater portion 

 of the toxin than does the second equal addition, this a 

 greater one than the third, and so forth. To explain this 

 peculiarity (of diphtheria-toxin) Ehrlich supposes that the 

 toxin is a mixture of many different " partial toxins," which 

 possess different degrees of toxicity in equivalent quantities, 

 and have a different affinity for antitoxin. If antitoxin 

 be added, it at first neutralises that part of the poison 

 which has the greatest affinity, and which also is the 

 strongest poison ; thereafter that with the' next greatest 

 affinity, which also is the second in toxic strength, and 

 so forth. At the end the very weakest portions appear 

 for neutralisation. Ehrlich designated these hypothetical 

 " partial poisons " with names coined from the Greek 

 language, as prototoxin, deuterotoxin, tritotoxin, epitoxin, 

 etc. 



If we apply Ehrlich's views to ammonia, this substance 

 should, according to the experiment of neutralisation by 

 boric acid, be composed of different " partial ammonias," 

 of which the strongest one should be neutralised first, 

 the second strongest next, etc. Of course this compli- 

 cated explanation cannot possibly be used for ammonia, 

 which we know is a very simple chemical compound of 

 high purity, but it was by Ehrlich and his pupils applied 

 to other poisons quite generally, e.g. to diphtheria-poison 



