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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    test-tubes are sterilised before filling, by placing them one over the other in a wire crate lying on its side, in which they are introduced into the hot-air steriliser and exposed for an hour to a temperature of 100° C. [The cotton-wool plugs should be inserted before sterilising.] The gelatine is introduced into the test-tubes with the aid of a pipette, care being taken that it does not soil the edge of the tube, and least of all comes in contact with that part of the inner surface which supports the cotton plug. In this manipulation the plug must be seized on the dorsal surface of the hand between two fingers, and extracted from the tube with a twisting motion ; the pipette is then filled and closed with the forefinger, which is only raised when the gelatine is to be allowed to run out into the tube. After this procedure has been repeated a few times, each worker in his own way acquires such a degree of expert- ness, that the greatest possible celerity is attained in filhng the tubes with gelatine and quickly reclosmg them. Instead of the pipette, the use of which always demands a certain amount of skill, small glass funnels may aptly be employed, or a glass tube capable of being closed by a tap may be attached to the funnel through which the gelatine is filtered and introduced into the test-tube to be filled. It is particularly to be observed that the gelatine must not be kept continuously at a high temperature, lest it should lose its power of solidifying when cold. It must, therefore, be heated in the steam apparatus for fifteen minutes on several—about three to five—days in succession, in order that the culture-medium preserved in the test-tubes may be completely sterile, and capable of being stored for future use in all bacteriological experi- ments. Preparation of meat extract peptone gelatine.—Hueppe’s meat-extract pej)tone gelatine is a 10 per cent, solution of