34 ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



may be thus formulated : any serum prepared for 

 human use, if found capable of giving rise to grave 

 anaphylactic symptoms in a sensitised guinea-pig in 

 doses of from 0-05 to o-6 c.c, should be discarded. 



Quantitative estimation of the toxicity by the 

 intracranial route is very simple. It can be done 

 instantaneously, and entails no expense. The guinea- 

 pigs that have been used for the dosage of diphtheria 

 antitoxin are quite suitable for this purpose. 



We may note, in passing, that high temperatures 

 distinctly diminish the toxicity of sera ; we shall deal 

 with this question in detail in the following chapter. 



To sum up : quantitative experiments have shown 

 that there exists a whole range of sera that are more 

 or less toxic. The variations in toxicity are con- 

 nected with the age of the sera and with factors that 

 are yet unknown. The sera are hypertoxic on the 

 day of venesection, but they lose their toxicity by 

 degrees; this lowering of toxicity, which is rapid to 

 commence with, slackens down from the tenth day 

 onwards. After two months, the toxicity due to the 

 age of the sera becomes negligible. Every serum 

 which sets up grave anaphylactic symptoms in the 

 dose of 0-05 to 0-063 c.c, and a fortiori below that 

 dose, should be considered toxic for man. 



Toxicity of Milk} — If we have insisted at so great 

 a length on the toxicity of serum it is, amongst other 

 reasons, on account of its practical interest. But it 

 is not only sera that are toxic : milk kills the sensi- 

 tised guinea-pig quite as often. As our experiments 

 have shown us, a quarter of a cubic centimetre of 

 milk injected subdurally destroys the sensitised 

 guinea-pig in a few minutes and sometimes o*i c.c. 

 is enough to cause death. 



The milk used for injection into the brain should 

 not be unboiled : very often we have seen guinea- 

 » Annates de I'lnstittU Pasteur, xxiii,, January, 1909. 



