ANAPHYLAXIS OR HYPERSUSCEPTIBILITY 31 



mal tissue, and bacteria, may give rise to anaphylactic 

 phenomena. 



Anti-anaphylaxis. — If an animal receive a second 

 injection of foreign protein material before the twelfth 

 day after the first injection, a condition of resistance 

 or decreased susceptibility may be set up (anti-ana- 

 phylaxis), and the symptoms of anaphylaxis will not 

 occur. This resistance may be kept up by repeated 

 injections at short intervals. This fact is of impor- 

 tance in the repetition of antitoxic serum for therapeu- 

 tic purposes. The mechanism of anti-anaphylaxis is 

 as yet unknown. 



Passive Anapliylaccis, — Anaphylaxis may be 

 brought about passively as well as actively. Thus, if 

 one animal be sensitized by an injection of foreign 

 protein and sufficient time be allowed to elapse for the 

 formation of the specific protein-splitting ferments, 

 introduction of its serum into a second animal will 

 sensitize the second animal to the protein in question. 

 Anaphylaxis will then follow immediately after the 

 injection of the second animal with the protein. 



The anaphylaxis reaction is made use of in the 

 diagnosis of several diseases. The various tuberculin 

 reactions of von Pirquet, WolfF-Eisner, Calmette, 

 ]\Ioro and others depend on this hypersusceptibility. 

 Tuberculous persons being " sensitized " by the tuber- 

 culous process, the application of tuberculin in these 



