TOXIC OR EXCITING INJECTION 33 



fatal (0-063 C.C.), the serum gives rise only to ana- 

 phylactic symptoms — grave, it is true, but not 

 necessarily fatal. After the two months' interval 

 the toxicity of the serum is indefinitely maintained at 

 the same level (lethal do3e=o-i25 c.c). All the sera 

 which we examined, and which were more than two 

 months old, exhibited the same degree of toxicity 

 (lethal dose=o-i25 c.c). It never entirely dis- 

 appeared. We have had occasion to examine a 

 bottle of antidiphtheritic serum about twenty years 

 old; as was indeed to be expected, it was only neces- 

 sary to inject a sensitised guinea-pig intracerebrally 

 with 0-25 c.c. to produce the anaphylactic syndrome in 

 the animal, followed by death in less than five minutes. 



Without our being authorised to make the state- 

 ment that a serum which is very toxic when injected 

 into a sensitised guinea-pig is equally so in the case 

 of man, it is clear that it is absolutely in our interest 

 to forbid the use of toxic sera in treating the human 

 subject. 



In only using serum which is at least two months 

 old we eliminate at any rate one factor in the causa- 

 tion of the toxicity. As to the other factors, if we are 

 unable to modify them by means of procedures which 

 will be indicated farther on, we can at least verify 

 their presence, form an estimate of their harmfulness, 

 and take measures accordingly. 



According to the rules drawn up by the Frankfort 

 Institute,^ every therapeutic serum should satisfy 

 four conditions: (i) it should be limpid; (2) it should 

 not contain any bacteria; (3) it should not contain 

 more than 0-5 per cent, carbolic acid; (4) it should be 

 devoid of free toxin, tetanus toxin especially- In 

 our opinion it is well to add a fifth desideratum which 



^ Otto, " Die staatliche Prufung der Heilsera," Arb. a. d. k. 

 Inst. f. Exper. therap. zu Frank, a. M. Jena, 1906, Heft :i., 

 pp. 1-86. 



