CHAPTER I. 



DEFINITION AND CLASSIFICATION OF THE BACTERIAL 

 POISONS. 



Ptomaines. — An exact classification of the chemical 

 factors in the causation of the infectious diseases can prob- 

 ably not be made at present. We know of two chemically 

 distinct classes, one of which contains substances which 

 combine with acids, forming chemical salts, and which in 

 this respect at least correspond with the inorganic and 

 vegetable bases. The members of this class are designated 

 as ptomaines, a name suggested by the Italian toxicologist, 

 Selmi, and derived from the Greek word wTo/ia, meaning a 

 cadaver. A ptomaine may be defined as a chemical com- 

 pound which is basic in character and which is formed by 

 the action of bacteria on organic matter. On account of 

 their basic properties, in which they resemble the vegetable 

 alkaloids, ptomaines may be called putrefactive alkaloids. 

 They have also been called animal alkaloids, but this is a 

 misnomer, because, in the first place, some of them are 

 formed in the putrefaction of vegetatale matter; and, in 

 the second place, the term " animal alkaloid " is more prop- 

 erly restricted to the leucomaines — those basic substances 

 which result from tissue metabolism in the body. While 

 some of the ptomaines are highly poisonous, this is not an 

 essential property, and others are wholly inert. Indeed, 

 the greater number of those which have been isolated up 

 to the present time do not, when employed in single doses, 

 produce any apparently harmfiil effects. Bkiegbr restricts 

 the term ptomaine to the non-poisonous basic products, and 

 designates the poisonous ones as "toxines." This is a 

 classification, however, which seems to be of questionable 

 utility. It is not always easy to say just what bodies are 

 poisoncftis and what are not. The poisonous action of a 



