BIOLOGY OF BACTERIA. 51 



ilar to the preceding, except that instead of occurring in 

 carbohydrates it takes place in nitrogenous bodies. The 

 first step seems to be the transformation of the albumins 

 into peptones, then the splitting up of the peptones into 

 a large number of gases, acids, bases, and salts. In the 

 process the innocuous albumins are frequently changed to 

 toxalbumins, and sometimes to distinct animal alkaloids 

 known as ptomaines. Vaughan and Novy declare the 

 term " animal alkaloid " to be a misnomer, as ptomaines 

 are sometimes produced from vegetable substances in 

 the process of decomposition ; they suggest the term 

 " putrefactive alkaloids" as preferable. The definition 

 of a ptomaine given by these observers is u a chemical 

 compound, basic in character, formed by the action of 

 bacteria on organic matter." The chemistry of these 

 bodies is very complex, and for a satisfactory description 

 of them Vaughan and Novy's book 1 is brief and excel- 

 lent. Among the ptomaines the following appear to 

 be important: Methylamin (CH 3 NH 2 ), the simplest or- 

 ganic base formed in the process of putrefaction; dime- 

 thylamin ((CH 3 ) 2 NH) ; trimethylamin (C 3 H 9 N = (CH 3 ) 3 N) ; 

 ethylamin (C 2 H 5 .NH 2 ); diethylamin (C 4 H U N == (C 2 H 5 ) 2 - 

 NH) ; triethylamin (C 6 H 15 N == (C 2 H 5 ) 3 N) ; propylamin 

 (C 3 H 7 .NH 2 ) ; butylamin C 4 H U N) ; iso-amylamin ; caproyl- 

 amin ; tetanotoxin ; spasmotoxin ; dihydrolutidin ; putres- 

 cin ; cadaverin ; neuridin ; saprin ; pyocyanin ; and tyro- 

 toxicon. It is supposed that the cases of ice-cream and 

 cheese-poisoning that sometimes occur are due to tyro- 

 toxicon produced by the putrefaction of the proteid sub- 

 stances of the milk before it is frozen into ice cream or 

 made into cheese. The safeguard is to freeze the milk 

 only when perfectly fresh and avoid adding the sugar and 

 flavoring substances, allowing the whole to stand some 

 time, and then freezing. Numerous others have been 

 described, some toxic, others harmless. 



It is to compounds of this kind that the occasional 

 cases of " Fleishvergiftung " or "meat-poisoning" are 



1 Ptomaines and Lcucomalnes. 



