A textbook of bacteriology : including the etiology and prevention of infective diseases and a short account of yeasts and moulds, haematozoa, and psorosperms / Edgar M. Crookshank.

  • Crookshank, Edgar M. (Edgar March), 1858-1928.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of bacteriology : including the etiology and prevention of infective diseases and a short account of yeasts and moulds, haematozoa, and psorosperms / Edgar M. Crookshank. Source: Wellcome Collection.

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    plugged sterilised test-tubes. These should be filled, with a sterilised pipette, to about one-third of their capacity. Formerly the tubes were sterilised by TyndalFs process of dis- continuous sterilisation. The tubes were placed in Koch's serum steriliser, with the temperature maintained for an hour or more at 56° C, and this was repeated for six successive days, the temperature on the last day being gradually raised to 60° C. This completed the sterilisation, and to solidify the serum the tubes were arranged in the inspissator at the angle required, and the temperature was kept between 65° 0. and 68° C. Directly solidification took place the tubes were removed. The new process is much less tedious, and consists in taking every possible pre- caution to obtain the blood without contamination by bac- teria in the air or in the vessels employed. There is then no need to sterilise the serum, and it can be coagu- lated immediately. The tubes are tested by placing them in an incubator at 37° C. for a week, and if any show signs of contamination they are discarded, and the rest Fig. 43.—Koch's Serum Sterilises. can be used or kept in stock. The serum should then present the character of being hard, solid, of a pale straw colour, and transparent. A little liquid collects at the lowest point, and the serum is sometimes milky in appearance at its thickest part. Loffier^s Blood Serum is prepared by mixing two-thirds of fresh serum with one-third of broth, prepared in the usual way but with the addition of 1 per cent, grape-sugar. The mixture is decanted into test-tubes, avoiding the formation of air-bubbles, and it is then coagulated in the usual way. The serum may be employed not only in test-tubes, but also in small flasks, glass capsules, or other vessels, all of which must be cleansed and sterilised. Hydrocele fluid and other serous effusions may be prepared in the same manner. Gelatine may be added to the serum in the pro- portion of 5 per cent.