310 PROTEIN POISONS 



guinea-pigs, and found that animals sensitized to a serum, 

 and given a non-fatal reinjection of the homologous serum, 

 after recovery survived the minimum fatal dose of anaphyl- 

 atoxin. From these experiments Bessau reached the 

 following conclusions: (1) The condition or state of anti- 

 anaphylaxis is not specific. (2) It is not due to absorption 

 of the ferment (antibody). (3) It is due to increased toler- 

 ance of, or lessened susceptibility to, the poison. Friedberger 

 and his students 1 have taken up these points, and by exact 

 quantitative experiments have demonstrated that the 

 state of anti-anaphylaxis, like that of anaphylaxis, is 

 strictly specific, but that it is true that increased tolerance 

 does play a part in the experiments as made by Bessau. 

 When an animal is simultaneously sensitized to two sera, 

 and after the condition of sensitization has been fully 

 developed, a non-fatal reinjection of one of these sera 

 renders the animal after recovery absolutely insusceptible 

 to any dose of the serum which has been employed in the 

 reinjection, but leaves it still susceptible to the second serum 

 in doses only slightly larger than those required to kill 

 control animals sensitized to that serum only. We can 

 make this plainer by the following statement. When an 

 animal is sensitized to two sera, two specific proteolytic 

 ferments are developed. When an animal in full sensitiza- 

 tion to both sera is treated with a non-lethal reinjection of 

 one of them, the specific ferment for this serum is exhausted, 

 and a certain amount of the poison is set free, not enough 

 to kill the animal, but enough to give the animal increased 

 tolerance to the poison. Consequently the fatal dose of the 

 other serum necessary to kill on reinjection, say, twenty-four 

 hours later, is larger than the minimum fatal dose when the 

 animal has been sensitized to only one serum. We demon- 

 strated (see page 139) many years ago not only that tolerance 

 to the protein poison can be increased, but that resistance 

 to living cultures of pathogenic bacteria may be increased 

 by repeated doses of the poison. Furthermore, we showed 



1 Zeitsch. f. Immunitatsforschung, 1912, xiv, 371. 



