ANAPHYLAXIS. 385 



The sensitizing agent in anaphylaxis has re- Antigen. 

 ceived the name of anaphylactogen, or sensibili- 

 sinogen, and may be defined as any substance 

 which, when taken into the body, produces a 

 specific hypersusceptibility, usually after an incu- 

 bation period of at least from five to seven days. 



The substances which have been demonstrated 

 to act as anaphylactogens are proteins or are in- 

 separably connected with proteins. That anaphy- 

 lactogens are closely related, or, as Friedberger, 

 Doerr, and others think, identical with those 

 bodies which produce complement deviation, anti- 

 bodies, and precipitins, is shown by the fact that 

 the same substances produce all three phenomena. 

 Thus, as with precipitinogens we have an anaphy- 

 laxis specific for species and for tissues. The 

 same tissues which are specific for precipitin for- 

 mation, crytalline lens, spermatozoa, and placenta, 

 also give a specific anaphylaxis, while those tissues 

 such as kidney, liver, etc., which produce only 

 species specific precipitins produce species specific 

 anaphylaxis. As an exception to this rule, it may 

 be mentioned that Wells does not find that iodized 

 albumin produces anaphylaxis specific for iodized 

 albumins rather than species specific reactions, as 

 was found for precipitins by Obermayer and Pick. 



One of the first questions which arose concern- Relation to 

 ing Theobald Smith's phenomenon was that of the 

 relation of the anaphylactogen to the diphtheria 

 toxin and antitoxin. In this case, the employment 

 of normal horse serum readily showed that an- 

 aphylaxis was independent of the diphtheria bacil- 

 lus derivitives and antitoxin present in the serum. 



