Natural immunity against toxins 337 



)ody fluids, but ultimately it always resolves itself into a chemical or 

 perhaps physico-chemical action of the substances of the organism of 

 the animal on the toxic substances of the poisons. 



In Mammals examples of natural immunity against certain 

 poisons are not rare. Almost a century ago Oken made the obser- 

 vation that a person who tried to poison a hedgehog with opium, 

 hydrocyanic acid, arsenic or mercury bichloride usually failed in his 

 attempts because of the great resisting power of this animal. Harnack 

 demonstrated that the hedgehog will withstand a dose of potassium 

 cyanide six times as great as that necessary to kill a cat in a few [354] 

 minutes (0*01 grm.). In Le win's* experiments the hedgehog was 

 found to resist the injection of powdered cantharides in a quantity 

 seven times as great as that which infallibly kills a dog and greater 

 also than the lethal dose for man. The same observer also confirms 

 the observation that a much larger dose of alcohol must be used in 

 order to intoxicate a hedgehog than is required to obtain the same effect 

 in the rabbit or even in the dog. Horvath^ fed hedgehogs for a fairly 

 long period with living cantharides. These Insectivora devour their 

 venomous prey without showing any sign of illness except a certain 

 degree of emaciation. When Lewin tried to ascertain the cause of 

 this natural immunity of the hedgehog he examined the blood of 

 this animal for a substance antitoxic to cantharidine. His experi- 

 ments were all negative ; but it is difficult to come to any definite 

 conclusion in this matter from the fact that the blood and blood 

 serum of the normal hedgehog are toxic for the small laboratory 

 animals. A similar objection had already been brought forward by 

 Phisalix and Bertrand in connection \nth their experiments, analogous 

 to those of Lewin, on the immunity of the hedgehog against the 

 venom of the viper. 



It has long been known that hedgehogs have a liking for certain 

 reptiles and wage an implacable war on snakes in general and on the 

 viper in particular. In its attack the hedgehog tries to avoid being 

 bitten, but when, as often happens, it fails to evade a bite the 

 inoculation of the viper's venom appears to be well borne. This 

 observation has been confirmed experimentally. Phisalix and 

 Bertrand^ have shown that the resistance of the hedgehog to the 



1 Deutsche med. Wchnschr., Leipzig, 1898, S. 373. 



2 Vrach, St Petersburg, 1897, p. 964. 



3 Compt. rend. Soc. de Hoi, Paris, 1899, p. 77; Bull. Museum d. hist, nat, Paris, 

 1895, 1. 1, p. 294. 



B. 22 



