38 A MANUAL OF BACTERIOLOGY 



of the chemical substances produced in one way or another 

 by their metabolic processes (see also p. 24). The toxic 

 bacterial products may be classified as follows : 



(1) Decomposition products. These are substances pro- 

 duced by the decomposition of the medium upon which 

 the bacteria are growing. Thus proteoses appear to be 

 formed by the anthrax bacillus and the pyogenic cocci. 



The ptomines form another group of these substances. 

 These are a very important group of nitrogenous bodies, 

 analogous to the vegetable alkaloids and mostly solid and 

 crystalline in nature, which are formed by the action of 

 bacteria on protein and albuminoid matter. They often 

 occur naturally in decomposing and putrefying food, 

 meat, fish, etc., and as many of them are virulent poisons 

 they are of considerable practical import. Poisoning by 

 tainted food may be due to the absorption of such toxic 

 ptomines, and this form of food-poisoning is known as 

 ptomine poisoning. A number of toxic ptomines were 

 isolated by Brieger from cultivations of pathogenic 

 microbes, and great importance was once attached to 

 them. They are referred to in the descriptions of the 

 various pathogenic organisms. 



Brieger 's work, however, needs revision, for his methods 

 were not such as to exclude alteration by the reagents 

 employed. 



Stevenson obtained traces of a highly poisonous crys- 

 talline ptomine from some sardines that had caused death. 

 Vaughan isolated a body, tyrotoxicon, apparently identical 

 with diazobenzene, from poisonous cheese and milk. It 

 seems to be developed by the action of organisms belonging 

 to the B. coli or B. lactis aerogenes types. Mytilotoxin 

 (C 6 H 35 N0 2 ) is the specific poison of toxic mussels. Such 

 mussels have invariably been subjected to sewage pollu- 

 tion and the poison is probably produced by the action of 

 bacteria derived from sewage. Neurin and muscarin are 



