Ergastic substances are non-protoplasm materials that one can find in cells.

Cellulose and starch are the main ergastic substances of plant cells.

Tannins are classified as ergastic substances, i.e., non-protoplasm materials found in cells.

Ergastic substances may appear in the protoplasm, in vacuoles, or in the cell wall.

The living protoplasm of a cell is sometimes called the bioplasm and distinct from the ergastic substances of the cell.