28 ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



is the cause of the duration of the hypersensitiveness. 

 It is due to this antibody that the animal, while still 

 seemingly quite normal, reacts in the violent manner 

 we are familiar with as soon as the sensibiligen is 

 reintroduced — that is to say, as soon as we proceed 

 to make what we have termed the test injection, or 

 toxic injection. 



What takes place in the animal at the point of 

 time when the sensibihgen encounters the sensibi- 

 lisin ? To this question we cannot give an exact 

 reply. We shall revert to it in detail when we dis- 

 cuss the theories of anaphylaxis. What is of present 

 importance to know is the fact that the anaphylactic 

 antibody, or sensibilism, does exist. With regard ta 

 passive anaphylaxis we have seen that nothing is 

 easier than to demonstrate it experimentally. Let 

 us recollect that not long ago observers as acute as 

 Gay and Southard denied its existence.* In order to 

 explain the anaphylactic state, these workers formu- 

 lated an imaginary substance contained in the serum : 

 this substance, or " anaphylactin," was held to 

 persist in the body after all the other constituent parts 

 had been eliminated from it, and this it was which 

 would directly sensitise the animal, in the same way 

 as a toxin or a stain selectively fixes on particular 

 cells. This conception, which, at the present day, 

 possesses only an historical interest, shews into what 

 a state of confusion even enlightened experimenters 

 have been led by anaphylaxis. 



How much time is needed for the formation of 

 sensibihsin — that is to say, for the state of anaphy- 

 laxis to arise ? As we have already remarked, it all 

 depends on the dose of sensibihgen ; when the dose is 

 weak the sensitisation is accomplished in eight days ; 

 when the dose of sensibiligen is stronger it needs a 



1 Journal of Medical Research, igo8, xviii., p. 407; ibid.. 1908^ 

 xix., pp. I, 5, and 17. 



