VITAL ACTIVITIES OF BACTERIA 149 



Many ptomains such as cadaverin and cholin are quite 

 well understood. By the oxidation of cholin there can be 

 produced the highly toxic muscarin, found by Schmeideberg 

 in a poisonous toadstool and by Brieger in certain decompos- 

 ing substances : 



C 5 H ]5 N0 2 . + = C D H 15 N0 3 

 Cholin Muscarin 



The ptomain tyrotoxicon was obtained from cheese, milk, 

 and ice cream by Vaughan and Novy. 



Since the name ptomain was given to the poisonous 

 products resulting from bacterial growth before these sub- 

 stances were chemically understood the term is often wrongly 

 applied to all poisons found in food. Thus the physical dis- 

 turbance following the consumption of decomposing meat, 

 cheese or milk due to true toxins or even living bacteria is 

 almost always referred to as ptomain poisoning. (See meat 

 poisoning bacteria.) It is, with our present knowledge of the 

 subject, very difficult if not impossible to distinguish between 

 the two causes. 



Pyocyanin (C 14 H 14 N 2 O). This produces the color in blue 

 or blue-green pus, and is said to be a ptomainic pigment. 

 Similar bodies of a basic nature may be found in the intestinal 

 contents as the products of bacterial decomposition. Some of 

 these are poisons which may be absorbed. It is believed that 

 the symptoms designated as coma and tetany may be ascribed 

 to the absorption of substances of this nature. 



Sulphuretted hydrogen (H 2 S). Sulphuretted hydrogen 

 is a very common product of bacterial action upon albuminous 

 substances or putrescent material containing free sulphates 

 or sulphites. Its presence is determined by pasting a piece of 

 paper moistened with lead acetate inside the neck of the flask 

 containing the culture, closing the mouth with a cotton wool 

 stopper, and over this again an India-rubber cap (black rub- 

 ber free from sulphur) . The paper is colored at first brown- 

 ish and later black; repeated observation is necessary, as the 

 color sometimes disappears towards the end of the reaction. 



