SOME POISONS AND THEIR 

 PREVENTION 



T ITTLE did the learned Dutchman Leeuwen- 

 I > hoek dream when, more than two hundred 

 years ago, he recorded, in his Arcana Naturce ', that 

 he had found " viva animalcula " in his saliva, that 

 this, the first beginning of bacteriology, would lead, 

 a couple of centuries later, to the inauguration of 

 a new era in the treatment of disease, in which 

 these so-called animalcula, from being considered 

 as curiosities, would come to be regarded as powers 

 for good and evil of the first importance. Protective 

 inoculation or serum theraphy, of which the public 

 have lately heard so much in connection with 

 diphtheria, is the direct outcome of bacterial in- 

 vestigations which during the last two decades 

 have been pursued with such zeal in every part of 

 the globe. 



The vast domain of immunity, which until re- 

 cently was an undiscovered country, is now being 

 bit by bit annexed, and in all directions workers 



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