ANAPHYLAXIS 47 



animal inoculated. It may pass off gradually in a 

 month or more, or may persist for an indefinite 

 period. A very minute quantity of protein at the 

 initial injection is sufficient to sensitise the animal ; 

 it is necessary that the second injection be of much 

 greater quantity to produce anaphylactic symptoms. 

 The time at which the second injection gives rise to 

 the most violent symptoms, moreover, is to a large 

 extent dependent upon the size of the sensitising dose : 

 the smaller the initial dose the shorter the incubative 

 period of the anaphylactic state. At reinjection the 

 symptoms are most severe when the injection is 

 made intravenously. 



In an animal suffering from anaphylactic shock 

 there is lowering of the blood pressure and a decrease 

 in its coagulability. When sensitised animals recover 

 from the second injection they are thereafter immune 

 — that is, they do not react to the subsequent injec- 

 tions of the same substance. This desensitisation, or 

 anti-anaphylaxis, as Besredka has named it, appears 

 immediately after the recovery from the second 

 injection. 



Anti-anaphylaxis may also be produced if animals 

 which have received the first or sensitising dose are 

 injected with comparatively large quantities of the 

 same substance during the pre-anaphylactic period. 

 This injection should not be given too soon after the 

 first dose, but rather toward the middle or end of the 

 pre-anaphylactic period. 



Anaphylaxis is a strictly specific condition ; so 



