On the cultivation of bacteria / by Edgar M. Crookshank.

  • Edgar Crookshank
Date:
[1886]
Catalogue details

Licence: Public Domain Mark

Credit: On the cultivation of bacteria / by Edgar M. Crookshank. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    sterilized water, previously placed on the perfectly clean cover-glass. This, when dry, is passed three times through the flame of a Bunsen burner or a spirit-lamp, and stained with a drop of fuch- sin or methyl-violet solution. From the micro-organisms transferred to the cover-glass before it is dried and stained, from any remnants of the colony which was examined, and from other colonies bearing exactly similar appear- ances, inoculations should he made in test-tubes of nutrient gela- tin and agar-agar. In this way pure cultivations are established, and the microscopical appearances of the growth in test-tubes can be studied. The slower growth of the micro-organisms in solid media, and the greater facility afforded thereby for examining them at various intervals and stages of development, is an additional point in favour of these methods; and the characteristic microscopical appearances so frequently assumed are, more especially in the case of morphological resemblance or identity, of the greatest im- portance. The colonies on plates of nutrient gelatin (examined with a low power) of Bacillus anthracis, or of Proteus mirabilis, the cultivations in test-tubes of nutrient gelatin of the bacillus of septicaemia in mice, and the brilliant and curious growth of Micro- coccus indicus upon nutrient agar-agar may be quoted as examples in which the appearances in solid cultivations are absolutely pathognomonic. As an example of the importance of these microscopical appearances in the case of morphological resemblance or identity, I need only refer to the comma-bacillus of Koch. This bacillus closely resembles in form the comma-bacillus of cholera nostras, and the comma-bacillus of the mouth, as well as a curved bacillus described as occurring in old cheese. From all these bacilli the bacillus of Koch is distinguishable by its mode of growth in nutrient gelatin when cultivated in test-tubes and on glass plates. No one, so far as I am aware, has yet been able to demonstrate the existence of a curved bacillus, which is exactly similar both morphologically and biologically to the comma-bacillus of Koch. We owe, therefore, to the methods of cultivation on solid media that the presence of this bacillus serves as a reliable index to the existence of Asiatic cholera, although it may bear no causal relation whatever to the disease. There are other facts brought to light by studying bacteria by the method of cultivation on the surface of nutrient gelatin. Not only do the colonies differ in size and colour, but sometimes the shapes assumed by the groups of bacilli are very characteristic. These appearances can be very readily demonstrated by making what is called in German a “ Klatch-praparat ” ; by this method, we [28]