Production of Gases 



59 



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The occasional cases of "Fleischvergiftung," "meat-poisoning," 

 or "Botulismus," are due to the development of toxic ptomains in 

 consequence of the growth of certain bacteria (Bacillus botulinus) in 

 the meat. Kaensche* has carefully investigated the subject, and 

 given 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 meat to become poisonous. 



With the increase of knowledge upon the toxic character of the 

 bacteria themselves, the importance of the toxic ptomains 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 decom- 

 position and fermentation, among them being CO2, HjS, NH4, 

 H, CH4. Gases produced by aerobic bacteria 

 usually fly off from the surface of the 

 culture unnoticed, but if the bacterium 

 be anaerobic and develop the lower part of 

 a tube of solid culture media, a visible bubble 

 of gas is usually formed about the colonies. 

 Such gas bubbles are almost invariably pres- 

 ent in cultures of the bacilli of tetanus and 

 malignant edema. 



To quantitatively determine the gas-produc- 

 tion, 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 ^ig- 16.— Smith's fcr- 

 reservoir. mentation -tube. 



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 thumb. The fluid is shaken thoroughly 

 with the gas and allowed to flow back and forth from the bulb to the closed 

 branch, and the reverse several times to insure intimate contact of the CO2 

 with the alkali. Lastly, before removing the thumb all the gas is allowed to 

 collect in the closed branch so that none may escape when the thumb is removed. 

 If CO2 be present, a partial vacuum in the closed branch causes the fluid to rise 

 suddenly when the thumb is removed. After allowing the layer of foam to 

 subside somewhat the space occupied by gas is again measured, and the difference 

 between this amount and that measured before shaking with the sodium 

 hydroxid solution gives the proportion of CO2 absorbed. The explosive character 

 of the residue is determined as follows: The cotton plug is replaced and the 

 gas from the closed branch is allowed to flow into the bulb and mix with the 

 air there present. The plug is then removed and a lighted match inserted into 



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



