INTRODUCTION. 



OUR knowledge of the toxins is of quite recent 

 date. It is hardly twenty years since we began to 

 acquire a knowledge of the facts that are detailed 

 in this volume, and to which modern medicine owes 

 its most recent and marvelous progress, particularly 

 in serotherapy. 



In this volume we have studied, besides the true 

 toxins substances of cellular origin and of albu- 

 minoid nature and unknown composition other 

 toxic substances, the nitrogenized alkaloidal bases 

 introduced into science through the researches of 

 Selmi, Armand Gautier, and von Behring, and 

 which are highly hydrogenized nitrogenous crys- 

 tallizable principles of definite chemical compo- 

 sition the products of the more or less advanced 

 breaking down of albuminoids. 



Although these principles differ widely, by rea- 

 son of their physiological properties as a whole, 

 from the toxic albuminoids, or true toxins, it 

 appears proper to consider them as products of 



