. General physiology; an outline of the science of life. 96 GENERAL PHYSIOLOGY motion, in the second they are moving somewhat more slowly, and in the last still more slowly. Since, therefore, only a gradual difference exists, it is impossible to establish a sharp limit. In living substance also there are different grades of mobility among the particles, , in one case the substance is like thin, in another case like thick liquid. In general, it possesses the consistency and mobility of raw white of egg, but it may be firmer, and certain constant differentiations of protoplasm may possess ev
. General physiology; an outline of the science of life. 96 GENERAL PHYSIOLOGY motion, in the second they are moving somewhat more slowly, and in the last still more slowly. Since, therefore, only a gradual difference exists, it is impossible to establish a sharp limit. In living substance also there are different grades of mobility among the particles, , in one case the substance is like thin, in another case like thick liquid. In general, it possesses the consistency and mobility of raw white of egg, but it may be firmer, and certain constant differentiations of protoplasm may possess even the con- sistency of a soft jelly approximating a solid condition, without , losing, however, the power of shifting its particles. Such a condi- I tion exists in muscle-fibres, flagella, cilia, the nucleus, and upon jthe surface of many protoplasmic masses that do not possess a. Fig. 36.—Orhitolites. Piece of the many-chambered calcareous disc, bearing outstretched pseudo- podial filaments. A, Undisturbed. S, By strong shaking the protoplasm of the pseudopodia has been stimulated to form globules and spindles. membrane, such as infusorian cells. The term solid is applicable to such cases only, if at all. But these cases of a more viscous con- sistency are always locally restricted within the cell; the rest of the cell-contents is always a thinner liquid. Finally, it should not be forgotten that within the liquid there may be deposited all sorts of solid elements of very various con- .sistencies, and that, therefore, the whole constitutes, not a homo- geneous liquid, but a mixture, or, as Berthold terms it, an emulsion. For this reason it appears inadmissible to speak of an " aggregate condition " of protoplasm, as many observers do. Strictly speaking, the term '" aggregate condition " can apply only to a homogeneous substance, not to a mixture containing substances that possess in themselves very various aggregate Please note that these ima
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