CHAPTER III 



THE SENSITISING OR PREPARATIVE INJECTION 



Sensitisation to serum by subcutaneous inoculation. Sensitisation 

 by way of the digestive tract. — Sensibiligen and its properties. 

 Attempts to attack its resistance by various agents. — Sensi- 

 tisation to milk. Sensibiligen of milk and its properties. 

 Oral and rectal sensitisation. — Sensitisation to egg-albumen. 

 Optimum doses. Duration of the anaphylactic State- 

 Heated and non-heated sensibiligens. — Passive anaphylaxis. 



From a study of the preceding pages it will be seen 

 that in the phenomena of anaphylaxis the same 

 substance — serum, milk, or egg-albumen — may be 

 exhibited under the guise of three different properties. 

 According to the circumstances of the experiment, 

 this substance may be sometimes sensitising, some- 

 times toxic, and, on the contrary, may sometimes 

 act as a vaccine. 



We shall study these three functions separately, 

 always keeping before us the example of serum which 

 is the substance of choice from the point of view of 

 anaphylaxis. 



Sensitisation with Serum. — We know already that 

 in order to sensitise the guinea-pig it is sufficient to 

 inject into it a minimum dose of serum (o-oi c.c.) 

 either subcutaneously or intraperitoneally. In the 

 majority of instances it is needless to repeat the 

 injection: one is sufficient. If it be repeated, we 

 can only sensitise the animal further if the doses of 

 serum are very weak. 



We can also sensitise with strong doses of serum 

 — ^with doses as strong as we hke {e.g., 5 to 10 c.c); 



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