ANAPHYLAXIS 245 



towards bacteria : by its very power of digesting and assimilat- 

 ing them it renders inoffensive those substances which, if 

 injected under the skin or into the blood stream, would perhaps 

 be toxic : it maintains the natural immunity. 



But for the present it must be pointed out that Besredka's 

 conception only applies to substances like serum which are 

 harmless in general to the normal body even when injected 

 direct into the veins. It is not necessarily true of the tox- 

 albumins, which are toxic from the first. 



We have briefly indicated two procedures for rendering a 

 sensitive animal resistant, narcosis during the test injection and 

 the method of continuous vaccination with small doses. The 

 same result may be obtained by heating the toxic serum to 

 certain definite temperatures. Heating produces an effect un- 

 realized hitherto by any chemical means. Serum heated to 

 1 00 C. (diluted to prevent coagulation) becomes practically 

 harmless for both intracerebral and intravenous injections : 

 But this heated serum, no longer lethal, can still protect 

 against the anaphylactic shock by gradually disintoxicating the 

 sensitive cells as in the method of small doses or narcosis ; no 

 doubt the mechanism is the same. 



Heating is thus a good means of lowering the toxicity of a 

 serum. But sera heated to 100 C. lose all preventive and 

 curative power, and it is impossible therefore to exceed 59-60 C. 

 Experiment shows that heating for several hours at this tem- 

 perature diminishes considerably the anaphylactic toxicity. 

 The reason for the low toxicity of the Pasteur Institute sera, 

 duly recorded by various laboratories, is simply that their 

 sterilization is effected by means of several heatings at a low 

 temperature (without antiseptics). 



Man is not alone in profiting by laboratory research on 

 anaphylaxis. In certain countries the Pasteur vaccine against 

 anthrax is injected along with a few c.c. of an anti-anthrax 

 serum : the method is named sero-vaccination. Many cattle 

 are inoculated over again every two years, so that severe 

 anaphylactic effects are not uncommon. Recently sero- 

 vaccination was repeated on 180 cattle in Roumania. The 



