30 TOXINS AND ANTITOXINS. 



as the monkey or rabbit, by gently heating, or even 

 by allowing it to oxidize and partially dry in the 

 air, or else by submitting it to the action of anti- 

 septics or alternating electric currents of very high 

 tension. 



Experiments have shown that a deadly virus, 

 attenuated by one of the means mentioned, may 

 be injected, without danger of death, into the living 

 animal; and what is still better, the animal thus 

 treated acquires the power of resisting large doses 

 of the virus, less and less attenuated, and that it 

 is possible to reach a point where the animal 

 economy may become habituated to very large 

 doses of a highly virulent virus without the organ- 

 ism experiencing any visible illness — that is, the 

 organism has been vaccinated with regard to the 

 particular virus. 



Experiments have shown that this property is 

 not peculiar to microbial virus alone, but that it 

 is common to the venoms the toxicity of which is 

 essentially due to some toxins, with the exception 

 of those agents noted. 



The attenuated viruses act, as vaccins, through 

 their soluble constituents, which, either directly, by 

 modifying the nutrition of certain cells, or indirectly, 

 by inducing reactions of the nervous centers which 

 preside over this nutrition, profoundly change the 

 conditions of life and give rise to the pathological 

 condition — the vaccined state. 



