SUPERSENSITIVENESS OR ANAPHYLAXIS 599 



Spaltproduct of protein. As is well known, the injection of a 

 foreign protein in this way gives rise to an anti-substance, for 

 example, a precipitin, and the combination of the two has the 

 property of fixing complement. Now Friedberger has shown 

 that the action of complement on a serum precipitate (antigen + 

 precipitin) produces a toxic body, which on being separated from 

 the precipitate by the centrifuge, and injected into an animal, 

 causes all the symptoms of anaphylaxis ; this body he calls 

 anaphylatoxin. He has also defined the quantitative relation- 

 ships subsisting between antigen, anti-substance, and complement, 

 which give rise to the greatest amount of anaphylatoxin. If the 

 proteid disintegration is accelerated and carried to a further point, 

 then non-toxic substances are formed. He has also shown that 

 anaphylatoxin is produced by the action of complement on 

 bacteria treated with their homologous serum, and also by the 

 action of normal serum alone on bacteria and even on coagulated 

 serum. The phenomena of anaphylaxis therefore constitute an 

 accident, as it were, in the process of immunisation, which is to 

 be regarded as a reaction of the living organism against the 

 introduction of foreign proteins. In this way there is also 

 explained the marked fall in complement in anaphylactic shock, 

 which has been found to occur by Friedberger, Scott, and others. 

 Friedberger holds that the various anaphylatoxins are similar, or, 

 at least, closely allied substances, there is nothing specific in 

 their nature ; what is specific is merely the combination of 

 antigen and anti-substance, which when acted upon by comple- 

 ment gives rise to the poisonous substance. 



Besredka considers that the sensitising and the toxic factors 

 in the horse serum are not one and the same. He finds that 

 serum heated to a certain temperature may still have the power 

 of inducing the condition of anaphylaxis, but has lost the power 

 of bringing about the toxic phenomena when injected into an 

 anaphylactic animal. This result has, however, been explained 

 by others as being due to the fact that the sensitising dose is so 

 much smaller than the toxic dose (vide supra) on re-injection ; 

 accordingly the effect of heat may be to reduce the latter below 

 the fatal limit without having a corresponding effect on the 

 sensitising dose. On the other hand, Gay and Southard do not 

 believe in the theory of a reaction body. They consider that 

 the condition depends on the presence of a substance in the 

 serum which they call anaphylactin, and which persists in the 

 blood of the guinea-pig for a long period of time. This acts as 

 a slight irritant to the nerve-cells, and produces in them an 

 increased affinity for certain molecules in the serum. Accord- 



