A system of medicine by many authors.

  • Allbutt, Thomas Clifford.
Date:
1909/1911
Catalogue details

Licence: In copyright

Credit: A system of medicine by many authors. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    faint pink tinge. It must now be counter-stained, preferably by a dilute solution (1 to 2 per cent) of methylene blue. Half to one minute is sufficient for this, and after washing in water, the preparation is ready to be mounted. Specimens of sputum dried on a cover-glass may be stained for five minutes in the fuchsin solution, and half a minute in the methylene blue solution, and mounted, after drying, in Canada balsam, or examined in water. For sections of tissues it is best to stain for fifteen minutes in the warm fuchsin solution, after sticking the preparation on the cover-glass or slide. After counter-staining with methylene blue the section is to be dried with fine filter paper, washed rapidly with alcohol, clarified with xylol, and mounted in xylol balsam. By this method the tubercle bacilli are the only micro-organisms stained red, the other organisms which may be present being decolorised by the acid. These, as well as the ground tissue and cells, are stained blue by the methylene blue. Gentian violet may be used as a stain for the tubercle bacillus, the specimen being fixed with iodine solution and decolorised with alcohol ; bismarck brown, eosin, or vesuvin may be used as a counter-stain. This method gives very good results ; but the other is more generally ser- viceable. Cultivation of the Bacillus.—The bacillus tuberculosis grows best at the temperature of the body. At low and high temperatures its growth is im])eded or completely stopped. The range of temperature at which it will groAv is between 28° and 42° C. It may be artificially cultivated by usino; various media. Solidified blood serum is the best for obtainins; the bacillus from the tissues, and was the one used by Koch in his first research. When the surface of the solidified blood serum is inoculated with pure tuberculous material, and the tubes are kept at a temperature of 38° C, no growth appears as a rule during the first week, but in from 7 to 10 days white specks are seen on the surface of the serum which, when examined under the microscope, appear as dry flakes. The growth extends in a circular manner from these foci, and the older growths, while still remaining dry, become crinkled and folded, presenting a very characteristic appearance. The growth is very slow, and it may be weeks before it covers a large area of surface. The bacillus may also be grown on other solid media, such as blood serum containing gelatine, or peptone-agar containing 4 to 8 per cent of glycerine. On peptone-agar without glycerine the bacillus does not grow. Glycerine not only aids the growth in solid media, but, in the percentage above-mentioned, stimulates the bacillus to grow in liquid media, as, for example, in peptone-bouillon. It can also be grown on potato in sealed tubes (Pawlowsky). Grown on solid media the bacillus is apt to lose its virulence. In liquid media containing glycerine the virulence may be maintained for a somewhat longer time. The action of direct sunlight is fatal to the bacillus, as was first shown by Koch. This has been confirmed by subsequent observations. Oxygen is necessary for the growth of the bacillus.