222 PROTEIN POISONS 



albumen to tryptic digestion and found that as the digestive 

 action advanced the sensitizing property receded. Some 

 have claimed to sensitize animals with peptone and even 

 with amino-acids, but since the minutest quantity of 

 protein suffices to sensitize, it is more reasonable to suppose 

 that the peptone and amino-acid preparations were not 

 absolutely free from protein. Vaughan and Wheeler have 

 shown that the poisonous portion of the protein molecule 

 does not sensitize in either small or large doses. Frances- 

 chelli 1 found that when tissue is autolyzed for months, and 

 until every trace of the biuret reaction is lost, the fluid 

 shows no diminution in its sensitizing properties. This 

 agrees with the finding of Vaughan and Wheeler, that their 

 non-poisonous portion of the protein molecule sensitizes 

 even when it does not respond to the biuret reaction. All 

 this suggests that the sensitizing group in the protein 

 molecule is not itself a protein, or at least not a biuret, body. 

 However, the sensitizing group is destroyed in normal 

 digestion, and it is only under abnormal conditions that 

 protein sensitization results through the alimentary canal. 

 We will return to this subject later. 



Whether or not all proteins contain the sensitizing group 

 cannot as yet be answered with certainty. According to 

 Doerr and Russ the globulin of the blood serum is the only 

 protein in that fluid which sensitizes, while Wells concludes 

 that in egg-white the albumen is the only active agent. 

 Wells purified the albumen of egg-white by recrystallization 

 after the method of Hopkins and Pinkus, and he found 

 that the purer his albumen, the smaller the amount neces- 

 sary to sensitize. Gay and Adler 2 attempted by fractional 

 precipitation of blood serum with ammonium sulphate to 

 separate the anaphylactogenic from the other protein 

 constituents, and they obtained an euglobulin which sensi- 

 tizes but does not prove toxic on the second injection. 

 Quite naturally it seemed to them that they had succeeded 

 in isolating the sensitizing constituent of blood serum, and 



i Archiv f. Hygiene, 1909, Ixx, 163. 2 Jour. Med. Research, xviii, 433. 



