CHAPTER I. 



I'l.l'INITION AND CLASSIFICATION OF THE BACTERIAL 



I '( I SONS. 



PTOMA'fNES. All exact classification of the chemical 

 factors in the causation of the infectious diseases can prob- 

 allv not l>e 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 nsjxvt at least correspond with the inorganic and 

 vegetable basis. The members of this class are designated 

 a- ptoma'ines, a name suggested by the Italian toxicologist, 

 SKLMI, and derive<l from the (Jreek word -rufia, meaning a 

 cadaver: A ptoma'ine may l>e 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 !>e called putrefactive alkaloids. 

 Thev have also been called animal alkaloids, but this is :i 

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

 formed in the putrefaction of vegetable matter; and, in 

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

 erlv re-tricted to the leucomaines -those basic substances 

 which result from tissue metabolism in the body. While 

 some .f the ptomaines are highly poisonous, this is not an 

 utial property, and others are wholly inert. Indeed, 

 the greater number of those which have Ixvu isolated up 

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

 produce any apparently harmful effects. BRIEGER 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 I unties are 

 poisonous and what are not. The poisonous action of a 



