CHAPTER II. 



CLASSIFICATION AND DEFINITION OF THE CHEMICAL 

 PRODUCTS OF BACTERIA. 



Ptomains. — While an exact classification of the chemical products 

 of bacterial growth cannot be made at present, we know of two dis- 

 tinct classes, one of which contains substances which combine with 

 acids fonning salts, and which in this respect at least corresponds 

 with the inorganic and vegetable bases. The members of this 

 class are designated as ptomains, a name suggested by the Italian 

 toxicologist Selmi, and derived from the Greek word nrw/za meaning 

 a cadaver. A ptomain may be defined as an organic chemical com- 

 pound, basic in character, and formed by the action of bacteria on 

 nitrogenous matter. On account of their basic properties, in which 

 they resemble the vegetable alkaloids, ptomains may be called putre- 

 factive alkaloids. They have also been designated as animal alka- 

 loids, but this is a 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 properly restricted to the 

 leucomains — those basic substances which result from tissue metabo- 

 lism in the body. Robert employs the term ptomatin as etymolog- 

 ically preferable to ptomaiin. 



While some of the ptomains are highly poisonous, this is not an 

 essential property, and others are wholly inert. Indeed, the greater 

 number of those which have been isolated do not, when employed in 

 single doses, produce any apparent harmful effects. Brieger has sug- 

 gested that the term ptomain be restricted to the non-poisonous basic 

 products, and he designates the poisonous ones as " toxins " ; how- 

 ever, such a classification would be of questionable utility. It will 

 be necessary for us to possess more extensive and exact knowledge 

 concerning the action of many of these substances before we can 

 decide positively which are poisonous and which are not. The effect 

 of a chemical compound upon the animal body depends upon the 

 conditions under which, and the time during which it is administered. 

 Thirty grains of quinine may be taken by a healthy man during 

 twenty-four hours without any appreciable ill effect, yet few of us 

 would be willing to admit that the administration of this amount 

 daily for months would be wise or altogether free from injury. In 

 the same manner, the administration of a given quantity of a bacterial 

 alkaloid to a dog or a guinea-pig in a single dose may do no harm, 

 while the daily production of the same substance in the intestine of a 



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