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Protoplasm


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), 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," but the nucleus also is composed of protoplasm, or living substance in its broader sense. The current consensus is 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)])". 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.

The word "protoplasm" comes from the Greek protos for first, and plasma for thing formed, and was originally used in religious contexts. It was used in 1839 by J. E. Purkinje for the material of the animal embryo. 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.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.


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