Biology of Bacteria 



Fig. 5. Smith's fer- 

 mentation-tube. 



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. Kaensche* 

 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. 



Production of Gases. Various gases 

 are given off during decomDOsition and 

 fermentation, among them being CO 2 , H 2 S, NH 4 , H, CH 4 , 

 and others. Gases produced by aerobic bacteria usually 

 fly off from the surface of the culture unnoticed, but if the 

 bacterium be anaerobic and develop at the lower part of 

 a tube of culture media, a visible bubble of gas is usually 

 formed about the colonies. Such gas bubbles are almost 

 invariably present in cultures of the bacilli of tetanus and 

 malignant edema. 



To quantitatively determine the gas-production, some 

 form of the Smith fermentation- tube is most convenient. 

 The tube is filled with bouillon containing some sugar, 

 sterilized as usual, inoculated, and stood aside to grow. 

 As the gases form, the bubbles ascend and accumulate in 

 the closed arm. In estimating quantitatively, one must 

 be careful that the tube is not so constructed as to allow 

 the gas to escape as well as to ascend into the main reservoir. 

 For the determination of the nature of the gases produced^ 

 Theobald Smith has recommended the following method : 



"The bulb is completely filled with a 2 per cent, solution 

 of sodium hydroxid (NaOH) and tightly closed with the 

 * "Zeitschrift fur Hygiene," etc., Bd. xxn, Heft i, June 25, 1896. 



