Manual of bacteriology / by Robert Muir and James Ritchie.

  • Robert Muir
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Manual of bacteriology / by Robert Muir and James Ritchie. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    rence of what is known as plasi?wlysis. To speak generally, when a mass of protoplasm surrounded by a fairly firm envelope of a colloidal nature is placed in a solution con- taining salts in greater concentration than that in which it has previously been living, then by a process of osmosis the water held in the protoplasm passes out through the membrane, and, the protoplasm retracting from the latter, the appearance of vacuolation is presented. Now in mak- ing a dried film for the microscopic examination of bacteria the conditions necessary for the occurrence of this process may be produced, and the appearances of vacuolation and of polkorner may thus be brought about. Plasmolysis in bacteria has recently been extensively investigated,1 and has been found to occur in some species more readily than in others. We may conclude that such appearances as vacuolation of the bacterial protoplasm and polkorner are either signs of degeneration, like the metachromatic granules, or are artificially produced. All of them are most frequently observed in old or otherwise enfeebled cultures. Butschli has published interesting observations on the minute struc- ture of some large sulphur-containing bacteria. These were found to consist of an outer membrane enclosing the protoplasm, which was divided into two parts—an outer protoplasmic network containing bac- terio-purpurin, and an inner part, the greater portion of the latter being stained blue with htematoxylin more deeply than the outer, in specimens out of which the bacterio-purpurin had been dissolved. In this central part thus stained there were red granules, which Butschli regards as the metachromatic granules of Ernst. The bacilli in the specimens he examined seem, however, to have been healthy. Butschli looks upon the outer part of the central body as corresponding to the protoplasm of an ordinary cell, the inner part as corresponding to the nucleus. In one smaller bacterium he found evidence of the former only at the end of the cell. He therefore thinks that the greater part of the bacterial cell may correspond to a nucleus, and that this is surrounded by a thin layer of protoplasm, which in the smaller bacteria probably escapes notice, unless when it is specially abundant at the ends. This terminal plasma has also been found by Wager in another bacterium. 1 Consult Fischer, Untersuchungen tiber Bakterien, Berlin, 1894; Ueber den Bau der Cyanophyceen und Bakterien, Jena, 1897.