The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis.

  • Curtis, Henry J.
Date:
1900
Catalogue details

Licence: In copyright

Credit: The essentials of practical bacteriology : an elementary laboratory book for students and practitioners / by H. J. Curtis. Source: Wellcome Collection.

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

    85/314 (page 67)
    PROTEUS MIRABILIS. PUTREFACTION made up of bacilli which are concentrically arranged in the bulbous extremity. No hquefaction of the gelatine occurs at first, and even after a considerable time it is but shghtly marked. The organism is motile; no spore formation is known. Under the microscope, every variety of shape is met with, cocci, diplococci, short rods and longer ones, threads, and involution forms. Impression preparations (fig. 42) show the typical grouping, and there is great variation in the length of the organism. Both varieties of Proteus just mentioned exhibit a pecuhar phenomenon when plates are made with 5 per cent, nutrient gelatine. At quite an early stage of incubation, a matter of a few hours only, and before liquefaction is visible, the bacilli themselves can be seen to be in active motion. As Crookshank points out, there probably is really a thin layer of liquefaction. Such motility is not observable if 10 per cent, gelatine is employed. Proteus mirabilis.—This is another variety of the Proteus found in putrefying animal matter and water, and. it appears to occur not infrequently in milk, where the long involution forms, often ter- minating in spindle-shaped swellings, are very characteristic. The ordinary bacilli are variable in length and shape, being sometimes round, and sometimes very thick rods with rounded ends. The organism is motile ; no spores are formed. Cultivations.—Gelatine stab.—A dense white layer of growth, circular in outline, forms on the surface of the medium. The lique- faction of the gelatine is not so rapid as in the case of P. vulgaris. Gelatine ])late.—The colonies, white to the naked eye, under the lower power of the microscope appear brownish-white, circular, or oval, and finely granular. The outline is wavy ; and from it, branches pass outwards into the surrounding medium, presenting much the same appearance as is seen in the case of P. molgaris. When plates are made with 5 per cent, nutrient gelatine, the pecuhar movement of the baciUi, already described in the case of P. vulgaris, &c., can be observed under the low power of the microscope before the onset of liquefaction becomes obvious. Putrefaction Putrefaction is the term used to cover a series of changes similar to those of fermentation (p. 57) by which complex organic bodies are reduced to simpler chemical su.bstances—changes which in the case of putrefaction occur after hfe has become extinct. Putrefaction has therefore been defined as putrid fermentation, or the fermentation of dead organic matter. The decomposition under F 2