Handbook of physiology / by W.D. Halliburton.

  • Halliburton, W. D. (William Dobinson), 1860-1931.
Date:
1919
Catalogue details

Licence: Public Domain Mark

Credit: Handbook of physiology / by W.D. Halliburton. Source: Wellcome Collection.

    36/974 (page 12)
    A streaming movement is not infrequently seen in certain of the protozoa, in which the mass of protoplasm extends long and fine processes, themselves very little movable, but upon the surface Fig. 11.—Human colourless blood-corpuscle, showing its successive changes of outline within ten minutes when kept moist on a warm stage. (Schofield.) of which freely-moving or streaming granules are seen. A gliding movement has also been noticed in certain animal cells; the motile part of the cell is composed of protoplasm bounding a central mass; by means of the free movement of this layer, the cell may be observed to move along. Fig. 12.—(a) Young vegetable cells, showing cell-cavity entirely filled with granular protoplasm enclosing a large oval nucleus, with one or more nucleoli. (b) Older cells from same plant, showing distinct cellulose-wall and vacuolation of proto¬ plasm. In vegetable cells the protoplasmic movement can be well seen in the hairs of the stinging-nettle and Tradescantia and the cells of Yallisneria and Chara; it is marked by the movement of the granules nearly always imbedded in it. For example, if part of a hair of Trade¬ scantia (fig. 13) is viewed under a high magnifying power, streams of protoplasm containing crowds of granules hurrying along, like the foot-passengers in a busy street, are seen flowing steadily in definite directions, some coursing round the film which lines the interior of the cell-wall, and others flowing towards or away from the irregular mass in the centre of the cell-cavity. Many of these streams of protoplasm run together into larger ones and are lost in the Fig. 13.—Cell of Tradescantia drawn at suc¬ cessive intervals of two minutes.—The cell- contents consist of a central mass connected by many irregular processes to a peripheral film, the whole forming a vacuolated mass of protoplasm, which is continually changing its shape. (Schofield.)