A manual of bacteriology, clinical and applied / by Richard T. Hewlett.

  • Richard Tanner Hewlett
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: A manual of bacteriology, clinical and applied / by Richard T. Hewlett. Source: Wellcome Collection.

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    BACTERIAL STRUCTURE Their size is variable, but they are all microscopic, measuring from 03^ to 30-40u in diameter or length. Their shape likewise is very different in the different species; some are spherical, others ovoid, others rod¬ shaped or filamentous, while in some the rod or filament is twisted into a spiral. The bacterial cell consists of a cell-membrane enclosing the transparent, more or less structureless living matter or bioplasm,1 the cell plasma. The cell-membrane in a few species may be composed of cellulose, but in the majority it consists of a protein substance. Btitschli has described the bacterial plasma as having a reticular structure, but in the young cell this is probably either an artifact or a ‘ false image ’ due to faulty illumination ;2 the most that can jjbe seen is a fine granulation. The bioplasm frequently contains larger granules composed of fatty or proteid matter, pigment, and in some species of sulphur. Occasionally certain granules stain blue with iodine. One to three spherical granules are also present in each cell; these seem to take part in the division of the cell (see below), and if the latter be stained with a very dilute mixture of roseine and methyl¬ ene blue are coloured pink, contrasting with the rest of the bioplasm, which is stained blue. Unless the roseine-staining granules, just mentioned, be regarded as such, no nuclear structure is present in the cell, nor does the theory which regards the bacteria as primitive nuclei almost devoid of bioplasm seem to be tenable. The bioplasm when dead, according to Nencki, differs from ordinary proteid matter in not being precipi¬ tated by alcohol and in not containing sulphur; it has been termed by him ‘ myko-protein.’ 1 The writer has preferred to employ the term ‘ bio-plasm ’ to designate that which is usually known as proto-plasm, though he is aware that it has been used by Lionel Beale in a 'more restricted sense.
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