ANAPHYLAXIS 289 



established fact that the injection into an animal of a foreign 

 protein— vegetable, animal or bacterial, simple or complex- 

 followed by a second injection after a proper length of time 

 leads to a series of symptoms indicating poisoning which 

 may be so severe as to cause the death of the animal. 

 Richet's term ''anaphylaxis'^ has been applied to the con- 

 dition of the animal following the first injection and indicates 

 that it is in a condition of supersensitiveness for the protein 

 in question. The animal is said to be "sensitized" for that 

 protein.^ The sensitization is specific since an animal 

 injected with white of chicken's egg reacts to a second injec- 

 tion of chicken's egg only and not pigeon's egg or blood 

 serum or any other protein. The specific poisonous sub- 

 stance causing the symptoms has been called "anaphylo- 

 toxin," though what it is is still a matter of investigation. 

 It is evident that some sort of an antibody results from the 

 first protein injected and that it is specific for its own antigen. 



A period of ten days is usually the minimum time that 

 must elapse between the first and second injections in guinea- 

 pigs in order that a reaction may result, though a large pri- 

 mary dose requires much longer. If the second injection is 

 made within less time no effect follows, and after three or 

 more injections, at intervals of about one week, the animal 

 fails to react at all it has become ''immune" to the protein. 

 Furthermore, after an animal has been sensitized by one 

 injection and has reacted to a second, then if it does not 

 die from the reaction it fails to react to subsequent injec- 

 tions. In this latter case it is said to be " antianaphylactic." 



It must be remembered that proteins do not normally get 

 into the circulation except by w^ay of the alimentary tract. 

 Here all proteins that are absorbed are first broken down 

 to their constituent amino-acids, absorbed as such, and 

 these are built up into the proteins characteristic of the 

 animal's blood. Hence when protein as such gets into the 

 blood it is a foreign substance to be disposed of. The blood 



1 The term "allergie" was introduced by von Pirquet to designate the 

 state of the animal's being sensitized and "allergic," as the adjective derived 

 therefrom. Allergy is quite generally used to indicate the condition of 

 natural sensitization, anaphylaxis that of artificial. 

 19 



