142 THEORIES CONCERNING IMMUNITY 



example by mixing with their respective antibodies harmless 

 albumin-antigens (like serum, casein, white of egg, etc.) 

 which are not toxic in themselves. For in such cases, the 

 two substances, each of them inoffensive, form a product a 

 precipitate which is toxic. 



The pathologic manifestations caused by these toxic mix- 

 tures are always the same, regardless of the nature of the 

 antigen-albumin (pathogenic bacillus, toxalbumin or ordi- 

 nary food albumin) . 



It follows by deduction that : 



The reactions caused by the toxic products of mixtures 

 in vitro or in vivo of antibodies with their antigens, always 

 affect the same organs and are always of the same nature. 



What is the nature of this reaction, and what justifies it? 



It may be assumed, with Metchnikoff and his school, that 

 the heterologous albumins like bacteria, undergo intracellular 

 digestion in the blood and in certain organs. Anti-infectious 

 immunity through phagocytosis would be only a particular 

 case of this intracellular digestion, or quoting Bordet, "a 

 fortunate and efficient application, for the defense of the 

 organism, of a primordial function wiiich would exist to the 

 same extent even if there were no pathogenic germs on the 

 surface of the earth." This theory, however, does not explain 

 the pathological manifestations which result from this 

 function. It does not explain and does not try to explain, 

 which substances, innocuous when first injected, become 

 pathogenic at the second injection, whereas true toxins, on 

 the contrary, become innocuous under the same conditions. 



These discoveries were registered without connection with 

 any general biological phenomena, and these questions had 

 to remain unanswered for a long time. 



ANAPHYLAXIS. 



It is evident that for minds that were neither prejudiced 

 nor governed by the theories of the time which inspired all 

 the foregoing experiments, the general rules which we have 

 just formulated-, contained already at this time (1897-1898) 

 all the elements which compose the phenomenon of anaphy- 



