Manual of bacteriology / by Robert Muir and James Ritchie.

  • Muir, Robert, Sir, 1864-1959.
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: Manual of bacteriology / by Robert Muir and James Ritchie. Source: Wellcome Collection.

    68/564 (page 44)
    as in I (rt), but after filtration 6 to 8 per cent of glycerine (sp. grav. 1.25) is added. This medium is especially used for growing the tubercle bacillus when the soluble products of the growth of the latter are required. 2. Gelatine Media.—These are simply the above broths, with gelatine added as a solidifying body. 2 {a). Peptone Gelatine.—Take of meat extract say 1000 c.c, add 5 grams sodium chloride, 10 grams peptone, and from 100 to 150 grams gelatine (the gold label gela- tine of Coignet et Cie., Paris, is the best). The gelatine is cut into small pieces, and added with the other constituents to the extract. They are then thoroughly melted on a sand bath, or in the Koch, and the fluid neutralised as in i (a), and filtered through filter paper. As the medium must not be allowed to solidify during the process, it must be kept warm. This is effected by putting the flask and funnel into a tall Koch's steriliser, in which case the funnel must be supported on a tripod, as there is great danger of the neck of the flask breaking if it has to support the funnel and its contents. The filtration may also be carried out in apt while melting to have settled into layers of different density. Sometimes what first comes through is turbid. If so, replace it in the unfiltered part: often the subsequent filtrate in such circumstances is quite clear. A litre flask F:g. 7.—Hot-water funnel. a hot-water funnel (Fig. 7). This consists of an outer tin funnel, the neck of which is fitted with a perforated cork, through which is placed the stem of an inner glass funnel, the diameter of whose mouth is less than that of the outer funnel. The interspace between the two funnels is filled with water, which is kept hot by a Bunsen under a side arm let into the outer funnel. Whichever instrument be used, before filtering shake up the melted medium, as it is