CHAPTER II. 

 TOXINS AND ANTITOXINS. 



WE have already seen, in the preceding chapter, 

 that the microbes and the cells of various organisms 

 are capable of secreting definite products of a 

 toxic nature to which the names "ptomaines " and 

 " leucomaines " have been given. Researches, 

 which were begun scarcely twenty years ago, 

 have shown that, besides these crystallizable 

 and definite products, we meet with basic non- 

 cry stallizable substances of unknown composition, 

 possessing special toxic properties, sometimes even 

 of extreme violence. These substances have been 

 named "toxins." 



At first this generic name was extended toward 

 indefinite basic organic products that could be 

 isolated from tissues and tumors both normal and 

 abnormal; later on, however, the name was ap- 

 plied to toxic substances, equally indefinite, isolated 

 from the culture media of microbes and the active 

 constituent of various venoms. 



It is only since 1885, when Charrin called at- 

 tention to them, that investigations began to be 



