Elements of bacteriology for practitioners and students : with especial reference to practical methods / by S.L. Schenk ; translated from the German (by the author's permission) with an appendix / by W.R. Dawson.

  • Schenk, Samuel Leopold, 1840-1902.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: Elements of bacteriology for practitioners and students : with especial reference to practical methods / by S.L. Schenk ; translated from the German (by the author's permission) with an appendix / by W.R. Dawson. Source: Wellcome Collection.

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    or feebly alkaline reaction. Turbidities are either caused by the reaction being strongly alkaline, and are in that case removed when this is corrected, or are due to a finely floccu- lent precipitate of albuminates, which are cleared away by adding the white of a hen’s egg and boiling for a quarter of an hour [with subsequent filtration]. Preparation of meat extract bouillon.—A second mode of making bouillon consists in the combination of meat-extract and sugar to obtain a liquid culture medium. The fol- lowing is Hueppe’s process:—To a litre of water are added ^ per cent (5 grams) of extract of meat and 3 per cent. (30 grams) of dry peptone, or instead of extract of meat and peptone, 2 to 3 per cent. (20-30 grams) of peptone of meat. A further addition of five grams of grape or raw sugar is then made, and the liquid boiled, carefully neutralised with solution of sodium carbonate, and subse- quently sterilised. Admixture of glycerine with the bouillon is also advantageous, and tubercle bacilli grow excellently on the medium thus obtained. Solutions of white of egg.—Solutions of white of egg are well suited to form fluid culture-media after they have been completely freed from germs by the discontinuous method of sterilisation. The white of p)lovers’ eggs lends itself well to this purpose, being clear and transparent, and capable of dilution with water, and of being filtered; it admits also of the addition of dextrine, sugar, or other ngredients according to need. The albumen when sterilised affords for a considerable time a suitable medium for culti- vations in test tubes or on glass plates placed in the moist chamber. Solid nutrient media.—Owing to the introduction of the use of solid culture media in bacteriological research, a series of micro-organisms have been more thoroughly examined, and it has thus been possible to observe that