122 CHEMISTRY OF BACTERIA AXD THEIR PRODUCTS 



orgranism may produce totally different ptoinauis when grown on 

 different media or under different conditions. Another essential dif- 

 ference is that w^e cannot obtain an immune serum, antagonizing the 

 action of ptomains, by injecting ptomai'ns into animals. 



Ptomains are chiefly the cause of disease when they are taken 

 in with food in which thej' have been produced by bacterial decom- 

 position. Besides this food poisoning, it is also possible that pto- 

 mains may be formed by putrefaction within the gastrointestinal 

 tract. Another possible source of ptomains is furnished by decom- 

 posing tissues in gangrene. It is doubtful if ptomains are produced 

 in sufficient quantities by pathogenic bacteria infecting living tissue 

 to be of any importance. Food poisoning is by no means uncommon, 

 but it is not always due to ptomains ; it may be the result of poisonous 

 materials contained abnormally in the food, that are not ptomains, 

 e. g., botulism ; or it may be due to an infection of the animal from 

 which the meat came with pathogenic organisms, particularly the 

 B. enteritidis of Gaertner and other bacteria related to the colon- 

 typhoid group ; or in other ways food ordinarily wholesome may be- 

 come poisonous. The commonest sources of ptomai'n poisoning are 

 imperfectly preserved canned meats, sausages, decomposing fish, 

 cheese, ice-cream, and milk.'^ 



Chemical Composition of Ptomains. — To indicate the composi- 

 tion and nature of i)tomains a few of the more important ones will be 

 described. As illustrative of the simpler forms may be mentioned: 



Methyl amine, CH3— JSTH,. 



Dimethyl amine, CH3— NH— CH3. 



Tri-methyl amine, CH3— N— CH3. 



CH3. 



These bodies, which are commonly found in decomposing proteins, 

 are but very slightly toxic, and of little pathological importance. 



The source of the ptomains in the various amino-acids is usually 

 easily traced through their chemical structure, and Ackermann and 

 Kutscher '* have classified them in this relation under the name 

 " aporrhegma." 



When we examine the structural formula^ of some of the larger 

 l)tomain molecules and compare them with the formula' of the amino- 

 acids that form the protein molecule, the relation is apparent, e. g., 

 compare iso-amylamine with leucine. 



CH3. CH3 



„„ > CH— CH,— CH,— NHj ^„ >CH— CH,— CH— NH, 



CHa^^ CJI3/ X 



(iso-amylamine) (leiicinp) ^('OOH. 



73 All tlipse matters are discussed at Icny^th hy ^ an^'liaii and Xovy. to wliose 

 hook llie reader is referred. 



-•Zeit. physiol. riiem., 1910 (69), 205. 



