POISONS AND THEIR PREVENTION 213 



of morphia causes an immediate reaction, and the 

 animal, after remaining in a more or less dazed 

 condition for several hours, finally succumbs to this 

 drug. Dr. Roux is inclined to regard this differ- 

 ence in the susceptibility exhibited by animals to 

 one and the same poison as being due to a good 

 deal of the toxin, when subcutaneously introduced, 

 failing to reach the nerve-centres, it having been 

 destroyed or arrested in the system before it could 

 attack them. 



What is the nature of the subtle forces which 

 may so beneficially intervene between the toxin 

 and its victim has long been a problem which 

 has excited the interest and ingenuity of some 

 of the most brilliant scientific authorities of the 

 day, and it is one which, even in the hands of 

 men like MetchnikofF, is still awaiting a satis- 

 factory solution ! 



The important point was next approached by 

 Dr. Roux as to whether an animal, successfully 

 trained to withstand large doses of the poison, as 

 ordinarily introduced, could also resist it when 

 directly inoculated into the brain. Is, in fact, the 

 undoubted immunity to tetanus poison which may 

 be possessed by an animal due to the nerve-centres 

 having become insensible to this substance ? The 

 answer to this question would appear to be in the 

 negative, for animals artificially protected from 



