PROTEIN SENSITIZATION OR ANAPHYLAXIS 235 



tion. We have repeatedly shown that the poisonous group 

 obtained from the protein molecule by cleavage with 

 chemicals or with ferments does not sensitize animals. 

 This is contrary to the generally accepted view, and our 

 claim on this point has met with either silence or denial, 

 but we have tested this matter so often and with poisons 

 obtained from so many and such a variety of proteins that 

 we have no hesitancy in affirming that the poisonous group 

 in the protein molecule does not sensitize animals. But it 

 is said that toxins are necessary to elaborate antitoxins, 

 and that the latter can be produced in no other way. This 

 is true, but the protein poisons are not toxins, and they 

 lead to the elaboration of no antibodies. The toxins are 

 specific; the protein poisons are not. The blood serum of 

 an animal treated properly with a toxin neutralizes the 

 toxin both in vitro and in vivo, while the blood serum of a 

 sensitized animal renders the protein with which the animal 

 has been treated, when brought in contact with it under 

 proper conditions, either in vitro or in vivo, poisonous. It 

 seems to us that it has been positively demonstrated that 

 the sensitizing and toxic groups in the protein molecule 

 are not the same. It might be argued that in ordinary 

 protein mixtures, such as blood serum and egg-white, one 

 protein may contain the sensitizing group and another the 

 toxic group. This may be true, but when pure proteins, 

 such as edestin, are used the two groups must exist in the 

 same molecule. The specificity of proteins is demonstrated 

 in sensitization. The toxic group shows no specificity. 

 This property characterizes the sensitizing group, and it 

 is in these groups that the fundamental and characteristic 

 property of each protein resides. The exact structure and 

 chemical nature of neither the sensitizing nor the poisonous 

 groups have been determined. The latter seems to be 

 physiologically the same in all proteins, the former is specific 

 in every protein. By our method, detailed in Chapter V, 

 the poisonous group is easily obtained; not in a chemically 

 pure condition, but so that its presence can be demon- 

 strated. The poisonous group, being the same in all proteins, 



