IMMUNITY REACTIONS 209 



P. HESSBERG observed that freshly prepared solution of sodium 

 palmitate bound complement, but it lost this property by repeated 

 heating. This change by means of repeated heating is a character- 

 istic colloid property, which evidently is associated with a fragmen- 

 tation of the particles; the more frequently gelatin, agar-agar, etc., 

 are heated, the more difficult it is to solidify them. Unfortunately 

 P. HESSBERG did not determine whether the repeatedly heated solu- 

 tion of sodium palmitate recovered, on long standing, its ability to 

 fix complement. 



ANAPHYLAXIS, DEFENSIVE FERMENTS, AND MEIO- 

 STAGMIN REACTION. 



Anaphylaxis. 



If an animal (e.g., a guinea pig) is injected with antigen (e.g., horse 

 serum) there are no sequelae. If the injection is repeated after an 

 interval of about 10 to 14 days there occur serious symptoms of poison- 

 ing (convulsions, rise of temperature and respiratory distress) which 

 frequently terminate fatally in a few minutes (anaphylactic shock). 

 This condition induced by the first injection of serum or bacteria is 

 called anaphylaxis (induced defenselessness the reverse of im- 

 munity). Human " serum sickness" is also a phenomenon of ana- 

 phylaxis which appears after the repeated injection of curative sera 

 and manifests itself in erythemata, swelling of the lymph nodes and 

 joints and moderate rises of temperature. Anaphylaxis is strongly 

 specific, which means that it occurs only upon repeated injections of 

 the same protein or the same strain of bacteria. The specificity is 

 so absolute and the quantities required so minute, that like precipita- 

 tin reactions, anaphylactic phenomena may be employed in dis- 

 tinguishing traces of human from animal blood or in detecting 

 adulterations. 



FRIEDBERGER and his coworkers were successful in preparing the 

 anaphylactic poison (anaphylatoxin) outside the body, in vitro. If 

 an animal (e.g., a guinea pig) is injected with antigen (e.g., horse 

 serum) antibody appears in the blood after a time. FRIEDBERGER 

 proceeded from this fact; he mixed antigen and antibody in a test 

 tube and obtained a precipitate from the mixture. By digesting 

 the precipitate with guinea-pig serum (which always contains com- 

 plement) he obtained what he designated as anaphylotoxin. 



Since peptones produce phenomena resembling anaphylactic shock, 

 it was thought that peptone-like products were split off, perhaps by 

 fermentation in the interaction between antibodies and antigen. 



