destruction of the lignin that fills the intermycelial spaces in the walls of plant cells. Delignification occurs in a dead cell through the activity of enzymes secreted by neighboring living cells or parasitic fungi that cause, for example, white rot of woody plants. In the stalks of herbaceous plants, the process precedes obliteration and destruction of the internal elements of the protoxylem. Delignification and subsequent thinning of the sclereid walls accompany the maturation of pears and quinces. Delignification is used in industry to obtain cellulose; the lignin is removed from the cell walls by boiling wood at high pressure with caustic soda or calcium bisulfite. Delignification may also be caused by the action of Schultze powder (nitric acid with Berthollet salt) on the cell walls.