Hand-book of physiology / by W.D. Halliburton.

  • Halliburton, W. D. (William Dobinson), 1860-1931.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: Hand-book of physiology / by W.D. Halliburton. Source: Wellcome Collection.

    40/886 (page 12)
    The Attraction Sphere. Recent research has shown that, in addition to the nucleus and protoplasm, most if not all living cells contain another structure ; it is.^ an extremely minute particle <which has been called the^ attraction sphere, because it. has an apparently attractive influence on the protoplasmic granules which radiate around it. rig. lo.—A cell white blood-cor- puscle showing its attraction sphere. In this as in most cases, the attraction sphere lies near the nucleus. (Schafer.) Fig. II.—Ovum of the worm Ascaris, showing a twin attrac- tion sphere. The nucleus with its contorted filament of chro- moplasm is represented, but the protoplasm of the cell is not filled in. (V. Beneden.) It is most prominent in embryonic cells, and in cells which are dividing or about to divide. Here it becomes double, and it is probable that the attraction sphere takes the lead in cell division, the nucleus and the cell-protoplasm then following suit. Protoplasmic Movement. A cell possesses the power of breathing, that is, taking in oxygen • of nutrition, of building itself up from food materials; and of excretion, or the getting rid of waste material. But the most obvious physiological characteristic of a cell is its power of movement. When an amoeba is observed wuth a high power of the microscope, it is found to consist of an irregular mass of proto- plasm containing one or more nuclei, the protoplasm itself being more or less granular and vacuolated. If watched for a minute or two, an irregular projection is seen to be gradually thrust out from the main body and retracted ; a second mass is then pro- truded in another direction, and gradually the whole protoplasmic