Production of Gases 



49 



Ptomains. Vaughan and Novy define a ptomain as "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* is excellent. 



Ptomains probably play but a small part in pathologic 

 conditions. They are formed almost exclusively outside of 

 the living body, and only become a source of danger when 

 ingested with the food. It is supposed that cases of ice- 

 cream and cheese- poisoning are usually due to tyrotoxicon, 

 a ptomain 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 mixing the milk, cream, 

 sugar, and flavoring substances, and allowing the mixture 

 to stand for some time beforehand. 



It is supposed that the occasional cases of "Fleischver- 

 giftung," "meat-poisoning," or "Botu- 

 lismus," are due to the development of 

 toxic ptomains in consequence of the 

 growth of certain bacteria (Bacillus 

 botulinus) in the meat. Kaenschef 

 carefully investigated the subject, and 

 gives a synoptic table containing all the 

 described bacteria of this class. His 

 researches show that there are at least 

 three different bacilli whose growth 

 causes the development of poisonous 

 ptomains in meat. In general these or- 

 ganisms resemble Bacillus coli. 



With the increase of knowledge upon 

 the toxic character of the bacteria them- 

 selves, the importance of the toxic pto- 

 mains has diminished, until at present 

 we have come to regard them as very 

 rare causes of disease. 



3. Production of Gases. Various 

 gases are given off during decomposi- 

 tion and fermentation, among them being CO 2 , H 2 S, 

 NH 4 , H, CH 4 , and others. Gases produced by aerobic bac- 

 teria usually fly off from the surface of the culture unno- 



* " Ptomaines and Leucomaines," 1888 ; "Cellular Toxins," 1902. 

 t " Zeitschrift fiir Hygiene," etc., Bd. xxn, Heft 1, June 25, 1896. 



4 



Fig. 5. Smith's fer- 

 mentation-tube. 



