100 ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



natant fluid portion, which conferred its toxicity on 

 this fluid. 



Now, the fact that the substitution of heated 

 serum for fresh serum is sufficient to arrest the pro- 

 duction of anaphylotoxin excluded this hypothesis. 

 This fact proved that the precipitate, if it still re- 

 mained, did not count for anything in the production 

 of the phenomenon. It is certainly, therefore, the 

 anaphylotoxin which possesses a definite toxic power. 



In order to complete the immunological picture of 

 anaphylotoxin, we may add that it resists heating 

 to 58° C. for half an hour; and that its toxic power 

 only disappears at 65" C. It is capable of being 

 precipitated by alcohol. It can be dried without 

 losing its properties; and becomes very toxic again 

 when redissolved in a small volume of water. 



Two of its peculiarities have appeared perplexing 

 to us from the outset of these researches, and our 

 especial attention has been drawn to them. The 

 first is that when injected directly into the brain the 

 anaphylotoxin does not produce any toxic eft'ect; 

 the second, that anaphylotoxin is produced even 

 when complement is brought into contact with 

 precipitate that has been heated to boiling-point. 



We shall return to the mention of these facts when 

 discussing the role of anaphylotoxin in anaphylaxis. 



The theory of anaph3dotoxins has found, as we 

 have already said, enthusiastic acceptance, especially 

 at the hands of Doerr and Russ. Not content with 

 espousing the theories of Friedberger so far as active 

 anaphylaxis is concerned, these workers have ex- 

 tended their application to passive anaphylaxis. We 

 have already shewn in Chapter III. that in order to 

 produce passive anaphylaxis to horse serum in a 

 guinea-pig, for example, one has only to inject into 

 it serum from a rabbit that in its turn has received 

 several injections of horse serum. 



