598 IMMUNITY 



young of anaphylactic mothers may also be anaphylactic, and the 

 condition may last for some time after birth. It is also possible 

 to produce a condition of anti-anaphylaxis, that is, to vaccinate 

 against the supersensitive condition. If, for example, the sensi- 

 tising dose of horse serum is injected, and then before ana- 

 phylaxis is established (i.e., some time before the twelfth day) 

 another injection of a considerable quantity of serum is made, 

 anaphylaxis does not appear, and the animal is non-susceptible to 

 further injections of small doses for a considerable period of time. 



With regard to the mechanism underlying the phenomena 

 described, practically all observers are agreed that there is a 

 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. 



Of even greater interest and importance than the mode of 

 action of the toxic substance developed, is the relation of the 

 phenomena of anaphylaxis to those of immunity. From the 

 facts above detailed it is manifest that at least two substances 

 are concerned in the production of the toxic phenomena, 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 " antiphy lactic reaction -body," which 

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

 two leads to the toxic effects. Thus Richet 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 



