THEORIES RELATING TO ANAPHYLAXIS m 



control, and, in fact, all the conjectures contained 

 in the theory appeared at once to find confirmation 

 by experiment. 



As soon as he had formulated his theor}^ Fried- 

 berger set himself the task of synthesising his ana- 

 phylotoxin in vitro. As we have just indicated, this 

 is a reaction product by three substances : 



Antibody =precipitin. 

 Antigen =precipitogen. 



Complement =: fresh serum. 



Friedberger then mixed precipitogen (sheep's serum) 

 with precipitin (rabbit's antisheep serum). After the 

 precipitate thus obtained had been well washed he 

 added guinea-pig's complement, and left this in 

 contact with the precipitate for twelve hours. The 

 next day he centrifuged the mixture. Upon testing 

 the supernatant fluid, he found that it was markedly 

 toxic, and that when injected intravenously into 

 fresh guinea-pigs it set up anaphylactic symptoms 

 in a few minutes, with rapid fall of temperature, delay 

 in coagulation of the blood, leucopenia, etc. 



If in this experiment serum heated to 55° C, and 

 not the fresh serum of the guinea-pig, is brought into 

 contact with the precipitate, anaphylotoxin, in 

 Friedberger's opinion, will not be formed. Conse- 

 quently, he considered that complement is necessary 

 for the production of anaphylotoxin. 



This experiment with heated serum led up to 

 another conclusion, none the less important. It 

 was known, indeed, from the time of the experiments 

 of Doerr and Russ that the precipitate alone was 

 capable of setting up grave symptoms when injected 

 intravenously. It might therefore be asked whether, 

 in the course of preparation of the anaphylotoxin, 

 there did not survive, in spite of the centrifugalisa- 

 tion, a small quantity of precipitate in the super- 



