PATHOGENIC BACTERIA 249 



teria which are not secreted outside the cell wall. These 

 poisons are specific substances. On account of being intra- 

 cellular, these toxic substances are called endotoxins. 



(d) Poisonous proteins which are constituents of the pro- 

 toplasm of the bacterial cell. These proteins are not in any 

 sense soluble or specific and are not definitely known to be 

 responsible for any morbid condition in the body. They may 

 be concerned in tuberculosis. These poisonous products are 

 called toxic bacterial proteins. 



Ptomains. These substances were the first bacterial prod- 

 ucts to be recognized. They were assumed to be alkaloidal 

 in nature, and on account of the fact that poisonous plants owe 

 their effects to alkaloidal substances, some observers were in- 

 clined to believe that ptomains were responsible for disease. 



Ptomains are basic nitrogenous substances and are found in 

 the media on which certain species of bacteria are growing. 

 It was soon determined that ptomains from pathogenic bac- 

 teria were not alone able to produce the morbid effects noted 

 in experimental animals. The most highly poisonous ptomains 

 are produced by the so-called non-pathogenic bacteria (sap- 

 rogenic bacteria). Only a small amount of research work has 

 been done on the subject of ptomains during recent years. 



Ptomains are formed by the action of various species of 

 saprogenic bacteria on protein material. They owe their 

 basic nitrogenous character to the amino groups which they 

 contain. It has been determined that ptomains may be pro- 

 duced by the action of saprogenic bacteria on dead pathogenic 



