150 THEORIES CONCERNING IMMUNITY 



These researches may be said to have brought out the 

 following general principles: 



1. Every organism capable of producing an antibody in 

 excess by the action of a given antigen, normally contains a 

 small quantity of this antibody. 



2. For the same quantity of antigen, the amount of pre- 

 cipitate formed in mixtures of antibody with its antigen, in 

 vitro and in vivo, as well as the speed of this formation, is 

 directly proportional to the quantity of antibody (normal or 

 in excess) which exists in the blood or in the serum. 



3. Every anaphylactized animal can be vaccinated in a 

 few minutes against a fatal anaphylactic shock, by the pre- 

 vious injection of a non-pathogenic dose of the same antigen; 

 in other words, a pathogenic anaphylactic reaction may be 

 prevented by a previous non-pathogenic reaction. 



TACHYPHYLAXIS OR SKEPTOPHYLAXIS. 



Long before the discovery of anti-anaphylaxis, a similar if 

 not identical phenomenon was known, which was discovered 

 and confirmed by a series of researches concerning the direct 

 toxic action of peptones and of certain albuminoid sub- 

 stances such as extracts of organs, eel serum, certain 

 poisons, etc. 



It was thus observed that the injection into a vein of 10 

 to 20 eg. of a peptone solution killed a dog in a few minutes. 

 Beginning with tachycardia, the crisis followed with dyspnea, 

 sometimes diarrhea, and ended with convulsions. The blood 

 of an animal so treated could no longer coagulate. Schmidt- 

 Mulheim was the first to observe that if the animal survived 

 a first peptone injection, its blood also was for a certain time 

 incapable of coagulation, but that this animal would endure 

 a second dose of peptone, even stronger than the first, without 

 any modification in the ability of the blood to coagulate. 



This phenomenon, confirmed by Fano (1882), Grosjean 

 (1892), for peptones was restudied more thoroughly by Roger 

 and Josue (1896) for intestinal extract. Delezenne demon- 

 strated this anticoagulating action for the extract from 

 crawfish, eel serum, etc. Delezenne and Bose (1896-1898) 



