TOXIC OR EXCITING INJECTION 29 



much longer interval — ^weeks, and sometimes months. 

 One thing is certain : whatever be the sensitising dose, 

 it is hardly possible to obtain an anaphylactic con- 

 dition in less than eight days. This is the interval, 

 according to our view, which is necessary for the pro- 

 duction of antibody in general, whether this be against 

 cells or against bacteria or against toxins . 



There are many ways of carrying out the test in- 

 jection in a sensitised animal: one may do it intra- 

 venously, intracerebral^, intraperitoneally, or even 

 subcutaneously. 



The intravenous route is the most effective of all ; 

 it also allows of our estabhshing the fact, quicker 

 than the other routes, that the animal is in an ana- 

 phylactic condition — ^sometimes at the end of seven 

 days. We should not, however, place too great 

 confidence in the intravenous test, especially in the 

 case of fluids containing particulate matter, cells, or 

 bacteria. One may, indeed, by its use set up embo- 

 lism and help in bringing about phenomena that en- 

 tirely simulate anaphylaxis though in reahty the 

 particular phenomenon present may be one of quite 

 a different nature. The intravenous test is some- 

 times attended by another disadvantage; when sub- 

 stances that alter the coagulability of the blood are 

 employed, such as peptone or organic extracts, the 

 intravenous route may tend to confusion and to an 

 erroneous interpretation of facts. We shall return to 

 this subject later. 



After the intravenous route, the intracerebral route 

 is the most effective ; this is the one we have adopted 

 from the beginning of our researches on anaphylaxis. 

 Without its possessing so great a sensitiveness as the 

 intravenous route, it has the advantage of not ex- 

 hibiting any of its drawbacks. Indeed, there is a 

 whole series of substances which when injected intra- 

 venously give rise to toxic symptoms which resemble 



