PUTREFACTION OF PROTEINS 93 



ring brine and are responsible for the characteristic odor 

 of this material. Putrescin and cadaverin — tetramethylene 

 diamine, and pentamethylenediamine respectively — 

 occur generally in decomposing flesh, hence the names. 

 They are only slightly poisonous. One of the highly poi- 

 sonous ptomaines is neurin CsHisNO or C2H3N(CH3)30H 

 = trimethyl-oxyethyl ammonium hydroxide. This is a 

 stronger base than ammonia, liberating it from its salts. 

 Numerous other ptomaines have been isolated and described. 

 These bodies were considered for a long time to be the cause 

 of various kinds of "meat poisoning," "ice cream poison- 

 ing," "cheese poisoning," etc. It is true that they may 

 sometimes cause these conditions, but they are very much 

 rarer than the laity generally beheve. Most of the "meat 

 poisonings" in America are due, not to ptomaines, but to 

 infections with certain bacilli of the Bacillus enteritidis 

 group. Occasionally a case of poisoning by the true toxin 

 (see Chapter XII) of Bacillus botulinus occurs. 



As ptomaines result from the putrefaction of proteins, so 

 they are still further decomposed by bacteria and event- 

 ually the nitrogen is liberated either as free nitrogen or 

 as ammonia. 



Another series of products are the so-called aromatic 

 compounds — phenol (carbolic acid) various cresols, also 

 indol and skatol or methyl indol (these two are largely 

 responsible for the characteristic odor of human feces). All 

 of these nitrogen compounds are attacked by bacteria and 

 the nitrogen is eventually liberated, so far as it is not locked 

 up in the bodies of the bacteria, as free nitrogen or as 

 ammonia. 



The carbon which occurs in proteins accompanies the 

 nitrogen in many_ of the above products, but also appears in 

 nitrogen-free organic acids, aldehydes and alcohols which 

 are all eventually split up, so that the carbon is changed to 

 carbon dioxide or in the absence of oxygen partly to marsh 

 gas. 



The intermediate changes which the sulphur in proteins 

 undergoes are not known, but it is liberated as sulphuretted 

 hydrogen (HaS) or as various mercaptans (all foul-smelling). 



