PROTEIN SENSITIZATION OR AN APR YL AXIS 265 



serum are distinct substances, the former being thermo- 

 labile and the latter thermostabile. The same investigators 

 demonstrated the same thing in another way. The toxin 

 of eel serum is destroyed by acidifying the serum with 

 hydrochloric acid, and is not restored on neutralization 

 (differing in this last respect from certain other toxins, 

 such as those of cobra poison and of diphtheria). Eel 

 serum when acidified with from 0.4 to 1 per cent, of hydro- 

 chloric acid and then neutralized has no poisonous action 

 in a single dose on guinea-pigs, but does sensitize them to a 

 second dose of the serum treated in the same way. Pre- 

 cipitation of eel serum by saturation with ammonium 

 sulphate carries down both the toxin and the anaphylac- 

 togen. Ox serum behaves in a similar way with eel serum 

 on guinea-pigs, and it also is robbed of its toxic property 

 when heated to 60. The blood serum of guinea-pigs 

 treated with unheated eel serum contains both antitoxin and 

 the substance produced by the anaphylactogen, and with 

 this serum fresh animals may be protected against unheated 

 eel serum and anaphylactized to heated serum. 



It follows from these researches that the substance 

 elaborated in the organism by an anaphylactogen is not 

 an antitoxin. This does not mean that the animal which 

 dies from the first dose of a toxic serum and the one that 

 dies from the second dose of a heated serum do not die 

 from the effects of the same poison. The toxic serum owes 

 its toxicity to a ferment which splits up the proteins of 

 the animal's body, setting a poison free. The unheated 

 serum leads to the elaboration in the animal's body of a 

 ferment which splits up the protein of the heated serum 

 on the second injection, setting a poison free. With the 

 toxic serum the ferment is introduced into the guinea-pig, 

 and splits up the proteins of the body. When the heated 

 serum is injected the cells of the guinea-pig elaborate a 

 ferment which splits up the proteins of the heated serum 

 on its second injection. In both instances the poison is 

 generated by the parenteral digestion of proteins, and in 

 all probability is the same. 



