Reports of the special Committee upon Pathological Methods. V, The reaction of media.

  • Great Britain. Medical Research Committee. Special Committee upon Pathological Methods.
Date:
1919
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Licence: Public Domain Mark

Credit: Reports of the special Committee upon Pathological Methods. V, The reaction of media. Source: Wellcome Collection.

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    careful asepsis in a still room sterile sugar solutions may be added to broth with the loss of comparatively few tubes. The methods for doing so are given in any text-book on bacteriology. REACTION OF Sorip MEDIA. Gelatine. The reaction of media containing gelatine may be easily determined if the medium is liquefied at 30°C. As a rule, gelatine is distinctly acid in reaction, and its addition to broth causes a rise in the hydrogen ion concentration of the mixture. Agar. The addition of a good quality agar to broth has but little effect on the latter. The reaction of the medium may be estimated in the liquefied medium, but the temperature at which this is done makes the determination difficult. It is therefore better to use a clean agar which, preferably, has been washed, and take the reaction of the broth as that of the complete medium. The reaction of the finished medium may be checked by adding the indicator to the liquefied medium, mixing it well and allow- ing it to cool thoroughly. The colours may then be compared, using the same precautions as in the case of broth. REFERENCES. 1. BARENDRECHT: A simple Hydrogen Electrode. Biochem. J., 1915, 9, 66. 2. Barnetr and CHapman: Colorimetric Determination of Reaction of Bacterio- logical Media and other Fluids. J. Am. M. Ass., 1918, 70, 1062. 3. CuaRK: The Reaction of Bacteriological Culture Media. J. Infect. Dis., 1915, 75 aLO9 4, CLARK and Luss: The Colorimetric Determination of Hydrogen Ion Concen- tration, and its Application in Bacteriology. J. Bact., 1917, 2, 1, 109, 191. 5. Cote and Onstow: On a Substitute for Peptone and a Standard Nutrient Medium for Bacteriological Purposes. Lancet, 1916, 2, 9, 1011. 6. Conn, Harpine, Kiianter, Frost, Prucua, and Arxins: Methods of Pure Culture Study. Progress Report for 1918 of the Committee on the Descriptive Chart of the Society of American Bacteriologists. J. Bact., 1919, 4, 107. 7. Dernpy and Avery : Optimum Hydrogen Ion Concentration for the Growth of Pneumococeus. J. Exper. M., 1918, 28, 345. 8. Homer: A Note on the Use of Indicators for the Colorimetric Determination of the Hydrogen Ion Concentration of Sera. Biochem. J., 1917, 11, 283. | 9. Hurwitz, Meyer, and Ostenpera: On a Colorimetric Method of Adjusting Bacteriological Media to any Optimum Hydrogen Ion Concentration. Proc. Soe. Exper. Biol. and Med., 1915, 13, 24. 10. Hurwirz, Meyer, and Ostensere : A Colorimetric Method for the Determina- tion of the Hydrogen Ion Concentration of Biological Fluids, with special Reference to the Adjustment of Culture Media, Bull. Johns Hopkins Hosp., 1916, 27, 16. 11. Luss and CiarK: On some New Indicators for the Colorimetric Determination of Hydrogen Ion Concentration. J. Wash. Acad. Sc., 1916, 6, 481. 12. McCienpon : Hydrogen and Hydroxyl Ion Concentr ation in Physiology and Medicine. Med. Rev. of Rev., 1916, 333, 13. MicHartrs: Die Wasserstoffionen-Concentrationen, Monographien aus dem Gebiet der Physiologie der Pflanzen und der Tiere. 1914, Bd. I, Berlin, Julius Springer. 14. WatroLte: Gas Electrode for General Use. Biochem. J., 1918, 7, 410.
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