Albert McGregor, age 14, of Jamestown, N.Y., for his question:

WART IS LIGNIN?

Lignin is a complex substance formed by certain plant cells. It is one of the chief substances in wood. Lignin, found in the cell walls of woody tissue, is closely associated with cellulose. It is made of the same elements as cellulose but its exact chemical composition is still unknown.

Lignin, like cellulose, permits water and gases to pass through it. It turns yellow when treated with sulfuric acids and iodine, while cellulose turns blue. In the manufacture of paper, lignin is removed from wood by treating the wood fibers with sodium sulfite.

Once regarded as a waste product in paper manufacturing, some lignin is now used as fuel in paper pulp mills.

Lignin is also used in making plastics, fertilizer, artificial vanilla, cosmetics, building board, rubber, fire extinguishers and other items.