116 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



changes characteristic of the diseases that the pathogen ic organ- 

 ism caused. Furthermore, the majority of ptomai'ns are not 

 very poisonous, and highly poisonous ptomai'ns may be produced 

 by non-pathogenic bacteria. As a result, the work on ptomains, 

 which twenty years ago occupied many laboratories and prom- 

 ised to reveal the entire chemistry of bacterial intoxication, has 

 now been almost completely dropped. The interest in ptomai'ns 

 is by no means entirely historical, however, for poisonous 

 ptomai'ns at times do enter the body and cause illness, some- 

 times even death. The close chemical resemblance to vegetable 

 alkaloids of some of the ptomai'ns that may arise in decom- 

 posing corpses, makes them of great importance to chemists 

 searching for the cause of death in cases of supposed poisoning. 

 Therefore the most essential features of the ptomai'ns and their 

 chief known relations to intoxications will be briefly discussed, 

 referring the reader for a full consideration to Vaughan and 

 Novy's " Cellular Toxins." l 



The ptomai'ns owe their basic character to nitrogen-containing 

 radicals, principally amino-groups, and hence are formed from 

 nitrogenous substances, chiefly proteids, which contain their 

 nitrogen in the amino form. Probably most ptomai'ns arise 

 from the decomposition of the proteid medium upon which the 

 bacteria grow, although undoubtedly part of the ptomains is 

 also formed from the destruction of the bacterial cells them- 

 selves ; how large a part of the ptomains is formed by intra- 

 cellular bacterial processes and how much by cleavage of the 

 proteids of the media by extracellular bacterial enzymes is 

 unknown. The structure of the ptomai'ns shows them to be very 

 closely related to the amino-acids obtained by cleavage of the 

 proteid molecule by enzymes and other hydrolytic agencies ; 

 hence it is probable that ptomains are produced by secondary 

 changes in the elementary nitrogenous " building stones " of the 

 proteid molecule, the amino-acids. Presumably these secondary 

 changes result from the action of special enzymes upon the 

 amino-acids, e. g. } urease (a bacterial enzyme) splits urea into 

 ammonia and carbon dioxide ; but possibly they are partly 

 due to interaction of the cleavage products upon one another. 

 Most of the ptomains are free from or poor in oxygen, hence 

 reduction processes are probably important in their production. 

 The poisonous ptomains, which are decidedly in the minority 

 among the entire group, are themselves subject to decomposition, 

 being most abundant in the cultures after a certain period of 

 time, and then decreasing in amount. Very old cultures show 

 1 Philadelphia, 1902. 



