4^ ANAPHYLAXIS AND ANTI-ANAPHYLAXIS 



symptoms. Heating the serum to loo** C. without 

 coagulation is sufficient, therefore, to render it com- 

 pletely harmless, even with the maximum dose 

 injected by the intradural route. Indeed, heating 

 the serum, though beneficial, from the point of view 

 of toxicity, is unfortunate from the point of view of 

 therapeutics. But, it might be asked whether in 

 heating sera to a lower temperature it would not be 

 possible perceptibly to reduce the toxic power, and 

 yet preserve the useful — that is to say, the preventive 

 and curative — ^properties . 



This is, indeed, what experience teaches. Three 

 parts of a serum of known toxicity were, after ade- 

 quate dilution (i : 4), heated respectively to ']6° ^ 

 89°, and 95° C. for twenty minutes. From each of the 

 three portions of the serum 0*25 c.c. was taken for 

 injection subdurally into sensitised guinea-pigs. In 

 order to demonstrate the toxicity of this serum 

 before heating, two sensitised guinea-pigs were in- 

 jected with 0*25 and o-i c.c. The first of these 

 guinea-pigs (0*25 c.c.) died in a few moments with 

 characteristic symptoms; the second (o-i c.c.) was 

 very resistant, and recovered half an hour after. In 

 the case of the guinea-pigs which were injected with 

 heated sera the results were as follows. One of two 

 guinea-pigs which was inoculated with serum heated 

 to 76° C. exhibited rather severe anaphylactic symp- 

 toms ; the other was scarcely ill at all. Four guinea- 

 pigs which were injected with sera heated to 89° and 

 95 ** C. shewed slight, hardly noticeable symptoms. 

 By means of these experiments we have satisfied 

 ourselves that the substance which is the cause of 

 the toxicity of sera is partially destroyed at a tem- 

 perature below 100° C. 



However, to be applicable to therapeutic sera, the 

 heating ought to be effective at temperatures still 

 lower than 'jt^ C. In order to obtain the maximum 



