POISONS AND THEIR PREVENTION 189 



vaccinated against rabies acquire the power of 

 resisting venom-poison, and that the serum of 

 horses vaccinated against tetanus or lock-jaw also 

 nullifies the action of serpent venom. 



The practical bearing of this discovery is 

 obvious, and the hope is justified that the at 

 present cumbrous appliances required for the 

 elaboration of anti-toxins of such varied origin 

 will ultimately give way to simpler and less costly 

 methods, which will admit of these new antidotes 

 being more widely circulated and applied. 



We have seen that although most animals fall 

 an easy prey to serpent venom, yet there are a 

 - few notable exceptions, amongst which may be 

 mentioned hedgehogs, swine, and the mongoose. 

 Now the very natural question arises why, if these 

 animals are already in such a high degree immune 

 from this poison, should not they be employed to 

 furnish forth protective serum, instead of labori- 

 ously training up susceptible animals to become 

 artificially immune and supply this venom anti- 

 toxin ? 



This brings us face to face with one of the 

 many problems connected with the subject of 

 immunity which so far have successfully eluded 

 all attempts made to solve them. Experience 

 has shown repeatedly that although artificially 

 acquired immunity from a particular poison can 



