PROTEIN SENSITIZATION OR ANAPHYLAXIS 311 



that in neither of these instances is the action specific, 

 nor does the poison have the action of a toxin, nor is the 

 increased tolerance of it due to the production of antitoxin. 

 Repeated treatment of animals with the poison, beginning 

 with a sublethal dose and gradually increasing the dose, 

 may enable the animal to bear three or four times the 

 minimum lethal dose, as tested on fresh animals, but the 

 effect induced is never quantitatively comparable to that 

 obtained by similar treatments with increasing doses of toxin. 

 Besides, we were never able to find any evidence of the 

 presence of an antitoxin in the blood serum of the treated 

 animal. For these reasons we decided years ago that the 

 protein poison is not a toxin. Moreover, we found that the 

 increased resistance to typhoid infection came just as 

 promptly and was as marked when the animal was treated 

 with poison obtained from egg-white as that obtained by 

 repeated treatments with the poison split off from the 

 cellular substance of the typhoid bacillus. This demon- 

 strated that the tolerance obtained to the protein poison 

 is not specific. This is another clear proof that the poisonous 

 group contained in the protein molecule is not a toxin. 

 Years after our work had been done and reported, Fried- 

 berger 1 found that after a guinea-pig had recovered from 

 severe poisoning with his anaphylatoxin, it would bear a 

 certainly fatal dose of the same, and at that time he thought 

 that he had secured a toxin-antitoxin immunity. Later 

 still H. Pfeiffer 2 found that the urine of an anaphylactized 

 guinea-pig is highly poisonous; also, that treating a sensi- 

 tized guinea-pig with such urine made it more resistant 

 on reinjection; also, that after recovery from anaphylactic 

 shock, guinea-pigs are more resistant to the poison in the 

 urine of anaphylactized animals. He also thought that 

 he had established a toxin-antitoxin immunity, but if we 

 read their later works with correct interpretation, neither 

 Friedberger nor H. Pfeiffer now believe that the protein 



1 Zeitsch. f. Immunitatsforschung, 1910, iv, 636. 



2 Ibid., 1911, x, 550. 



