Fermentation organisms : a laboratory handbook / by Alb. Klöcker; translated from the german by G. E. Allan and J. H. Millar.

Date:
1903
Catalogue details

Licence: In copyright

Credit: Fermentation organisms : a laboratory handbook / by Alb. Klöcker; translated from the german by G. E. Allan and J. H. Millar. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    other in the eye-piece it may be then noted how many divisions of the micrometer are equal to a certain number on the stage micrometer. If, for example, 2 divisions of the stage micrometer ( = 20 ya) correspond with 7 divisions, of the micrometer of the eye-piece, the apparent size ex- pressed in divisions of the eye-piece micrometer have to be multiplied by -y- = 2*857 in order to get the true length expressed in [i. The higher the magnification, the smaller is this factor. Counting Apparatus.—In order to be able to count yeast cells a “ net ” eye-piece is used, consisting of a circular piece of glass on which is etched a square, divided up Fig. 7.—Hsematimeter. [a] The object glass ; (6) the cut-out cover glass fastened on to it. (After Hayeni-Nachet.) into sixteen or twenty-five smaller squares; it is fitted up in the same way as the micrometer in the eye-piece and is used in conjunction with a hsematimeter. This (Fig. 7) is a glass slip (a), to which is fastened a cover glass (5), from the middle of which a circular piece has been cut out. A drop of liquid containing the cells to be counted is- placed in the shallow space thus formed and enclosed by an ordinary cover glass. The thickness of the perforated cover glass is usually 0*1 or 0*2 mm. Thonia’s hsematimeter (Fig. 8) is also used for counting micro-organisms. A is a glass slip, on which a cover glass (a) is fastened which has a circular hole in the middle and is 0*2 mm. thick. A circular cover glass (c), 0*1 mm. thick,