CHAPTER IV. 

 THE MICROBIAL TOXINS. 



THERE is but one way of characterizing the toxic 

 poisons secreted by microbes, and that is to apply 

 to them the name of the microbes generating them ; 

 thus the soluble and toxic poison of the tetanus 

 bacilli has received the name tetanus toxin. 



In toxic microbial cultures it is necessary to 

 distinguish the toxins proper from the toxic 

 alkaloids (ptomaines) which generally accompany 

 them; this is easily accomplished by evaporating 

 the solution in a vacuum at about 30 C., and 

 then treating with alcohol and ether, in which the 

 alkaloids are soluble, while the true toxins are 

 insoluble. By fractional precipitation with alcohol 

 it is easy to isolate the peptones and true toxins. 



The microbial toxins possess two essential prop- 

 erties; one the pyogenic property, thanks to 

 which the toxins first attract, then destroy the 

 white blood corpuscles or leucocytes, and trans- 

 form them into pus, and the other the pyretogenic 



property, which appears to belong only quite 



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