598 IMMUNITY 



profound toxic affection of the nervous system ; but it is still 

 an open question to what extent the action is central, to what 

 extent peripheral ; both modes are probably concerned. A great 

 fall in the blood-pressure is an important phenomenon in the dog 

 and rabbit, and is due chiefly to a vaso-dilatation in the abdomen, 

 which can be only partly counteracted by the administration of 

 atropine or barium chloride. It has been pointed out by Auer 

 and Lewis that in the case of guinea-pigs there occurs a spasm 

 of the muscle fibres in the fine bronchi and alveolar passages, 

 the chest-wall being fixed in full inspiration at the time of 

 death. Amelioration of symptoms by the administration of 

 ether or chloral, or by lowering the intracranial pressure by 

 trephining, would, on the other hand, point to the importance 

 of a central action. 



From the facts above detailed it is manifest that at least two 

 substances are concerned in the production of the toxic pheno- 

 mena, one present in the serum injected (antigen), which is in 

 itself non-toxic, and another developed in response to the injection 

 of the antigen, usually called the " antiphylactic reaction-body," 

 which is also non-toxic ; the union, or at least the co-operation, 

 of these two leads to the toxic effects. Thus Bichet considers 

 that the antigen gives rise to the production of a body which he 

 calls toxogenin and that these unite to produce the active poison 

 " apotoxin." The transference of the toxogenin by the injection 

 of the serum of an anaphylactic animal into a fresh animal 

 would accordingly explain the phenomena of passive anaphylaxis. 

 The most detailed analysis of the subject has, however, been 

 given by Friedberger, who explains the phenomena as resulting 

 from the process of digestion of protein, introduced parenterally ; 

 the toxic agent in anaphylaxis is a disintegration product 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 fix- 

 ing 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 



