H6 ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



anaphylactic immunity depends upon the slow 

 neutralisation of the sensibilisin by the antigen — 

 that is to say, on the progressive desensitisation of 

 the animal. Anaphylactic shock is also a desensitisa- 

 tion ; only, instead of being slow, it is rapid : the 

 whole difference is in the time of reaction. 



Imagine a flask of sulphuric acid to which water 

 is to be added. If all the water is poured in at once, 

 a kind of shock or explosive discharge is produced, 

 due to the rapid liberation of heat. 



On the contrary, if the water is poured in in small 

 quantities, even if these quantities are increased 

 progressively at the cost of a series of insignificant 

 shocks, the acid will in a very short time be weakened 

 or desensitised, so that afterwards any amount of 

 water can be added without the least risk of an 

 accident. 



