PUTREFACTIVE ORGANISMS 103 



rence are various methylamines, ethylamines, certain 

 diamines, such as cadaverine and putrescine, and choline 

 and betaine. Most of them are harmless compounds or 

 only poisonous when taken in large amounts. Many, 

 however, are known which are exceedingly dangerous 

 even in minute doses, and the consumption of putrid 

 or decomposing foods containing them not infrequently 

 leads to fatal results. Muscarine, which has been 

 obtained from putrefying fish, neurine from decomposing 

 flesh, and tyrotoxicon from rotten cheese, are examples 

 of this poisonous class. Similar bodies have been 

 isolated from decaying shell-fish, tinned sardines, and 

 other foods which have undergone putrefactive changes. 



It may be noted here that certain pathogenic bacteria, 

 such as the bacilli of tetanus and diphtheria, when 

 grown in culture solutions, are able to produce or secrete 

 much more deadly substances than the ptomaines just 

 mentioned. These are termed toxins, but little is known 

 about their chemical nature : some of them appear to 

 be proteoses, while others resemble enzymes. 



Sulphuretted hydrogen and methylmercaptan are 

 generally present in putrefying substances, and are 

 derived from organic sulphur compounds such as cysteine, 

 although in some instances bacteria are able to reduce 

 sulphates with the formation of hydrogen sulphide. 

 What becomes of the phosphorus of proteins is not 

 clear. It is said to be given off from decaying fish and 

 other organic materials as phosphoretted hydrogen, but 

 there is some doubt about this statement. 



2. Putrefactive Organisms. Although experiments 

 with pure cultures have shown that a great many species 

 of bacteria are able to bring about putrefactive decom- 

 position in materials containing protein, many of them 



