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(Science: cell biology)

The fluid living content of the cell that consists of two major divisions, the cytoplasm and the nucleoplasm (cell nucleus). It is composed mainly of nucleic acids, proteins, lipids, carbohydrates, and inorganic salts.


Charles Darwin and his 19th century contemporaries viewed "protoplasm" as the holistic content of a cell; in other words, cells were composed of a mysterious "proto-plasm," a substance that had the ability of self replication.

Word origin: From Greek (proto-), “‘first’” + (plasma), “‘something molded’”. The word was in Late Latin, meaning "first created thing," and may have existed in Medieval Greek in a different sense. It was used by Czech physiologist Johannes Evangelista Purkinje to denote the gelatinous fluid found in living tissue. This word prevailed, though Germanic language purists preferred urschleim (“‘original mucus’”).

Related forms: protoplasmic (adjective), protoplasmal (adjective).
Related phrases: totipotential protoplasm.

Compare: cytoplasm, nucleoplasm.