Ergastic substances are non-
protoplasm materials found in
cells. The living protoplasm of a cell is sometimes called the
bioplasm and distinct from the ergastic substances of the cell. The latter are usually organic or inorganic substances that are products of metabolism, and include crystals, oil drops, gums, tannins, resins and other compounds that can aid the organism in defense, maintenance of cellular structure, or just substance storage. Ergastic substances may appear in the
protoplasm, in
vacuoles, or in the
cell wall.
Starch, as starch grains, arise almost exclusively in plastids, especially leucoplasts and amyloplasts.
Although proteins are the main component of living protoplasm, proteins can occur as inactive, ergastic bodies—in an amorphous or crystalline (or crystalloid) form. A well-known amorphous ergastic protein is gluten.
Animals eliminate excess inorganic materials; plants mostly deposit such material in their tissues. Such mineral matter is mostly salts of calcium and anhydrides of silica.
