n. An albuminoid substance, ordinarily resembling the white of an egg, consisting of carbon, oxygen, nitrogen, and hydrogen in extremely complex and unstable molecular combination, and capable, under proper conditions, of manifesting certain vital phenomena, as spontaneous motion, sensation, assimilation, and reproduction, thus constituting the physical basis of life of all plants and animals; sarcode.n. The invisible basis of living substance; the ultimate and true protoplasm as free from all non-living objects. See the extract.n. Chemical structure. To chemical examination protoplasm yields large amounts of proteids and of water, as well as some fats, carbohydrates, and mineral substances. Of these the proteids are preëminent in some fundamental phenomena of protoplasm. Whether the ultimate protoplasm is one chemical substance or a mixture of substances is not known. Visible portions of protoplasm are complex and non-homogeneous in most cases and minute contiguous areas give different chemical reactions.n. Physical structure. Protoplasm is essentially liquid in many of its active phases, with great differences of viscosity in different areas and in the same area at different times. It often looks like an emulsion and some of its properties S.—68 are comparable with those of colloidal solutions. Assuming electrical charges in protoplasm, such fundamental activities as contraction of muscle and transmission by nerves have found formal explanations.n. Deduced biological structure. To explain heredity and some other phenomena of living things, protoplasm has frequently been regarded as made up of units which are generally thought of as ultramicroscopic. Among such units of ultimate protoplasm are the ‘physiological units’ of Herbert Spencer, the ‘gemmules’ of Darwin, the ‘pangens’ of De Vries, the ‘plastidules’ of Haeckel, the ‘biophores’ of Weismann, the ‘micellæ’ of Nägeli, and the ‘plasomes’ of Wiesner. In some cases these units are held to have some of the fundamental attributes of living things. These conceptions afford only formal explanations of certain protoplasmic phenomena.
