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Protoplasm is the living content of a cell that is surrounded by a plasma membrane.

In some definitions, it is a general term for the cytoplasm (e.g., Mohl, 1846),[1] but for others, it also includes the nucleoplasm (e.g., Strasburger, 1882). For Sharp (1921), "According to the older usage the extra-nuclear portion of the protoplast [the entire cell, excluding the cell wall] was called "protoplasm," which was unfortunate because we now know that the nucleus also is composed of protoplasm, or living substance in its broader sense. It is now the general custom to avoid this ambiguity by employing Strasburger's [(1882)] terms cytoplasm [coined by Kölliker (1863), originally as synonym for protoplasm] and nucleoplasm ([term coined by van Beneden (1875), or] karyoplasm, [used by] Flemming [(1878)])".[2][3][4][5][6] The cytoplasm definition of Strasburger excluded the plastids (Chromatoplasm).

As for the nucleus, the inclusion or not of the vacuole in the protoplasm concept is also controversial.[7]


The word "protoplasm" comes from the Greek protos for first, and plasma for thing formed, and was originally used in religious contexts.[8] It was used in 1839 by J. E. Purkinje for the material of the animal embryo.[9][10] Later, in 1846 Hugo von Mohl redefined the term (also named as Primordialschlauch, "primordial utricle") to refer to the "tough, slimy, granular, semi-fluid" substance within plant cells, to distinguish this from the cell wall and the cell sap (Zellsaft) within the vacuole.[11][12][13] Thomas Huxley (1869) later referred to it as the "physical basis of life" and considered that the property of life resulted from the distribution of molecules within this substance. Its composition, however, was mysterious and there was much controversy over what sort of substance it was.[14][15]

In 1872, Beale would create the vitalist term "bioplasm", to contrast with the materialism of Huxley.[16][17] In 1880, term protoplast was proposed by Hanstein (1880) for the entire cell, excluding the cell wall,[18][19] and some authors like Julius von Sachs (1882) preferred that name instead of cell.[20]

In 1965, Hardy introduced the term "cytosol", later redefined to refer to the liquid inside cell.[21]

Other related terms are:[22] Urschleim (Oken, 1802, 1809),[23][24] sarcode (Dujardin, 1835, 1841),[25][26] Grundsubstanz (ground substance, Cienkowski, 1863),[27] enchylema/hyaloplasma (Hanstein, 1880), paramitome (Flemming, 1882),[28] inter-filar substance (Velten, 1876)[29] and inter-alveolar substance (Bütschli, 1892).[30]

By the time Huxley wrote, a long-standing debate was largely settled over the fundamental unit of life: was it the cell or was it protoplasm? By the late 1860s, the debate was largely settled in favor of protoplasm. The cell was a container for protoplasm, the fundamental and universal material substance of life. Huxley's principal contribution was to establish protoplasm as incompatible with a vitalistic theory of life.[31] Attempts to investigate the origin of life through the creation of synthetic "protoplasm" in the laboratory were not successful.[32]

The idea that protoplasm of eukaryotes is simply divisible into a ground substance called "cytoplasm" and a structural body called the cell nucleus reflects the more primitive knowledge of cell structure that preceded the development of electron microscopy, when it seemed that cytoplasm was a homogeneous fluid and the existence of most sub-cellular compartments, or how cells maintain their shape, was unknown.[33] Today, it is known that the cell contents are structurally very complex and contain multiple organelles.


Protoplasm is composed of a mixture of small molecules such as ions, amino acids, monosaccharides and water, and macromolecules such as nucleic acids, proteins, lipids and polysaccharides.[34] In eukaryotes the protoplasm surrounding the cell nucleus is known as the cytoplasm and that inside the nucleus as the nucleoplasm. In prokaryotes the material inside the plasma membrane is the bacterial cytoplasm, while in Gram-negative bacteria the region outside the plasma membrane but inside the outer membrane is the periplasm.

Protoplasm was said to exist in two forms: a liquid-like sol state or a jelly-like gel state.

See also[edit]


  1. ^ Cammack, Richard; Teresa Atwood; Attwood, Teresa K.; Campbell, Peter Scott; Parish, Howard I.; Smith, Tony; Vella, Frank; Stirling, John (2006), Oxford dictionary of biochemistry and molecular biology, Oxford [Oxfordshire]: Oxford University Press, ISBN 0-19-852917-1 
  2. ^ Sharp, L. W. (1921). Introduction To Cytology. New York: McGraw Hill, p. 25.
  3. ^ Strasburger, E. (1882). Ueber den Theilungsvorgang der Zellkerne und das Verhältnis der Kernteilung zur Zellteilung. Arch Mikr Anat, 21: 476-590, BHL.
  4. ^ Beneden, E. van (1875). La maturation de l'oeuf, la fécondation et les premières de développement embryonnaire des Mammiferes d'après les recherches faites chez le lapin. Bull. Acad. Bel. Cl. Sci. 40, 2 sèr.: 686-736, BHL.
  5. ^ Flemming, W. (1878). Beiträge zur Kenntniss der Zelle und ihrer Lebenserscheinungen. Arch. f. mikr. Anat., 16: 302-436, p. 360, BHL.
  6. ^ Battaglia, E. (2009). Caryoneme alternative to chromosome and a new caryological nomenclature. Caryologia, 62(4), 1.
  7. ^ Parker, J. 1972. Protoplasmic resistance to water deficits, p. 125-176. In: Kozlowski, T. T. (ed.), Water deficits and plant growth. Vol. III. Plant responses and control of water balance. Academic Press, New York, p. 144, [1].
  8. ^ Wayne, R. 2009. Plant Cell Biology: From Astronomy to Zoology. Amsterdam: Elsevier/Academic Press, p. 133.
  9. ^ Purkinje J.E. 1840. Über die Analogien in den Strukturelementen des thierischen und pflanzichen Organismus. In: Übersicht der Arbeiten und Veränderungen der schlesischen Gesellschaft für vaterländische Kultur, Jahre 1839: 81.
  10. ^ Bynum, W. F., Browne, E. J. & Porter, R. (1981). Dictionary of the history of science. Princeton University Press.
  11. ^ von Mohl, H. 1846. Ueber die Saftbewegung im Inneren der Zellen. Bot. Ztg. 4: 73-78, 89-94.
  12. ^ Larson, P. R. (1994). The Vascular Cambium: Development and Structure. Springer-Verlag: New York and Berlin, p. 30-31, [2].
  13. ^ Evert, R. F. 2006. Esau's Plant Anatomy: Meristems, Cells, and Tissues of the Plant Body: Their Structure, Function, and Development. 3rd.ed. John Wiley & Sons, Inc: Hoboken, New.Jersey, p. 16, [3].
  14. ^ Huxley, T. H. 1869. The Physical Basis of Life. New Haven, Conn., The College Courant.
  15. ^ Harvey, E. N. (1938), "Some Physical Properties of Protoplasm", Journal of Applied Physics, 9 (2): 68, doi:10.1063/1.1710397 
  16. ^ Beale, L. S. (1872). Bioplasm. London: J. & A. Churchill.
  17. ^ Bynum et al. (1981), p. 344.
  18. ^ Hanstein, J. 1880. Das Protoplasma. Heidelberg.
  19. ^ Sharp (1921), p. 24.
  20. ^ Wayne (2009), p. 15.
  21. ^ Lardy, H. A. 1965. On the direction of pyridine nucleotide oxidation-reduction reactions in gluconeogenesis and lipogenesis. In: Control of energy metabolism, edited by B. Chance, R. Estabrook, and J. R. Williamson. New York: Academic, 1965, p. 245, [4].
  22. ^ Sharp (1921), p. 11, 32-34.
  23. ^ Grundriss der Naturphilosophie.
  24. ^ Lehrbuch der Naturphilosophie.
  25. ^ Dujardin, F. 1835. Recherches sur les organisms inférieurs. Annales des Sciences Naturelles 4: 343–377, [5].
  26. ^ Dujardin, F. (1841). Histoire Naturelle des Zoophytes Infusoires. Paris: Librarie Encyclopedique de Roret. p. 26.
  27. ^ Cienkowski, L. 1863. Zur Entwicklungsgeschichte der Myxomyceten. Jahrb. Wiss. Bot. 3: 325-337, [6].
  28. ^ Flemming, W. (1882). Zellsubstanz, Kern, und Zelltheilung. Vogel, Leipzig, [7].
  29. ^ Velten, W. 1876. Die physikalische Beschaffenhoit des pflanzlichon Protoplasmas. Sitzber. Akad. Wiss. Wien, Math.-Nat. Kl., 73: I 131-151, [8].
  30. ^ Bütschli, O. 1892. Untersuchungen über mikroskopische Schäume und das Protoplasma. Leipzig, [9].
  31. ^ Geison, Gerald (1969), "The Protoplasmic Theory of Life and the Vitalist-Mechanist Debate", Isis, 60: 272–292, doi:10.1086/350498 
  32. ^ Lazcano, A.; Capone, S.; Walde, P.; Seebach, D.; Ishikawa, T.; Caputo, R. (2008), "What Is Life? A Brief Historical Overview", Chemistry & Biodiversity, 5 (1): 1–15, doi:10.1002/cbdv.200890001, PMID 18205130 
  33. ^ Satir, P. (2005), "Tour of organelles through the electron microscope: A reprinting of Keith R. Porter's classic Harvey Lecture with a new introduction", The Anatomical Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology, 287A (2): 1184–1204, doi:10.1002/ar.a.20222, PMID 16265625 
  34. ^ Arthur C. Guyton; John E. Hall, Textbook of Medical Physiology, Eleventh Edition, Saunders, Protoplasm is composed mainly of five basic substances: water, electrolytes, proteins, lipids and carbohydrates.