American Heritage® Dictionary of the English Language, Fourth Edition
- n. The complex, semifluid, translucent substance that constitutes the living matter of plant and animal cells and manifests the essential life functions of a cell. Composed of proteins, fats, and other molecules suspended in water, it includes the nucleus and cytoplasm.
Century Dictionary and Cyclopedia
- 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. It is essential to the nature of protoplasm that this substance consist chemically of the four elements named (with or without a trace of some other elements); but the molecule is so highly compounded that these elements may be present in somewhat different proportions in different cases, so that the chemical formula is not always the same. The name has also been somewhat loosely applied to albuminous substances widely different in some physical properties, as density or fluidity. Thus the hard material of so-called vegetable ivory and the soft body of an amœba are both protoplasmic. The physiological activities of protoplasm are manifested in its irritability, or ready response to external stimuli, as well as its inherent capacity of spontaneous movement and other indications of life; so that the least particle of this substance may be observed to go through the whole cycle of vital functions. Protoplasm builds up every vegetable and animal fabric, yet is itself devoid of discernible histological structure. It is ordinarily colorless and transparent, or nearly so, and of glairy or viscid semifluid consistency, as is we'll seen in the bodies of foraminifers, amœbæ, and other of the lowest forms of animal life. Such protoplasm (originally named sarcode), when not confined by an investing membrane, has the power of extension in any direction in the form of temporary processes (see
pseudopodium) capable of being withdrawn again; and it has also the characteristic property of streaming in minute masses through closed membranes without the loss of the identity of such masses. An individuated mass of protoplasm, generally of microscopic size, and with or without a nucleus and a wall, constitutes a cell, which may be the whole body of an organism, or the structural unit of aggregation of a multicellular animal or plant. The ovum of any creature consists of protoplasm, and all the tissues of the most complex living organisms result from the multiplication, differentiation, and specialization of such protoplasmic cell-units. The life of the organism as a whole consists in the continuous waste and repair of the protoplasmic material of its cells. Noanimal, however, can elaborate protoplasm directly from the chemical elements of that substance. The manufacture of protoplasm is a function of the vegetable kingdom. Plants make it directly from mineral compounds and from the atmosphere under the influence of the sun's light and heat, thus becoming the storehouse of food-stuff for the animal kingdom. Protoplasm appears to have been first recognizably described by Rosel, in or about 1755, in his account of the proteus-animalcule. It was observed, not named, seventeen years later by Corti, in the cells of Chara. Like motions of protoplasm were noticed by Meyen in 1827 in Vallisneria, and by It. Brown in 1831 in his discovery of the cyclosis in the filaments of Tradescantia. In 1835 Dujardin called attention to a “primary animal substance” in the cells of foraminifers, described as “a sort of slime” endowed with the property of spontaneous motion and contractility, and called it sarcode. The word protoplasm was first used (in the form protoplasma) by Hugo von Mohl, in 1846, with reference to the slimy granular semi-fluid contents of vegetable cells. The identity of this vegetable “protoplasm” with animal “sarcode,” suggested in 1850 by Cohn, who regarded this common substance as “the prime seat of almost all vital activity,” was confirmed by Schultze in 1861; Virchow had in 1858 abandoned the idea that a cell-wall is necessary to the integrity of a cell, holding that a nucleus surrounded by a molecular blastema (that is, protoplasm) constitutes a cell, and Sehultze defined the cell as protoplasm surrounding a nucleus, which since that time the term has come into universal use. Also called bioplasm, cytoplasm or cytioplasm, and plasmogen. See these words, and cuts under amœbaand cell, 5.
- 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.
- n. cytology The entire contents of a cell comprising the nucleus and the cytoplasm. It is a semi-fluid, transparent substance which is the living matter of plant and animal cells.
GNU Webster's 1913
- n. (Biol.) The viscid and more or less granular material of vegetable and animal cells, possessed of vital properties by which the processes of nutrition, secretion, and growth go forward; the so-called “ physical basis of life;” the original cell substance, cytoplasm, cytoblastema, bioplasm sarcode, etc.
- n. the substance of a living cell (including cytoplasm and nucleus)
- From German Protoplasma, coined by Czech physiologist Johannes Evangelista Purkinje, from Ancient Greek πρῶτος (prōtos, "first") + πλάσμα (plasma, "something molded"). The word was in Late Latin, meaning "first created thing," and may have existed in Medieval Greek in a different sense. (Wiktionary)
“The term protoplasm is still in use with different meanings as used by different writers.”
“From this time forth this term protoplasm was applied to the living material found in all cells, and became at once the most important factor in the discussion of biological problems.”
“This common base is the physical and chemical character of the mixture of substances which we call protoplasm ....”
“I began with what I called the protoplasm of religion, the primitive ideas and practices which form the psychological basis of the whole growth.”
“We do not know, it is said, by what means the structureless viscid substance which we call protoplasm can build for itself a solid bone; we do not understand how an amoeba makes its test; no one understands how anything is done unless he can do it himself; and even then he probably does not know how he has done it.”
“A hundred years ago, when scientists believed cells were full of a mysterious substance they called protoplasm, that was a legitimate scientific question.”
“The body protoplasm is generally crescentic; there are two chromatin masses, the larger one, the nucleus, on the side of the convexity, the other narrower, more deeply stained situated usually on the edge of the concavity, the centrosome.”
“To this material he now gave the name protoplasm, choosing a name hitherto given to the cell contents of plant cells.”
“And we have seen that the essential substance of a cell is a complex chemical compound we call protoplasm, whose elements are identical with chemical substances outside the living world.”
“ The word protoplasm must not be misunderstood to mean a substance of a definite chemical nature, or of an invariable morphological structure; it is applied to any part of a cell which shows the properties of life, and is therefore only a convenient abbreviation for the phrase "mass of living matter.”
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original; primitive; first or anterior
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protoplasm, microchimerism, organelle, panspermia, housekeeping gene, double crossover, incomplete dominance, bacteriophage, connectomics, antigenic drift, inoculation, punctuated equili... and 138 more...
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