Mary Michele, Age 8, Of Voorheesville, N.Y.., for her question:

What is a living cell?

All plants and animals are made from tiny cells, and these cells were all made by other cells. The body of a grown person is made from about one million billion cells. An egg yolk is a large cell, but most cells are far too small for our eyes to see. We need a microscope to magnify them. And the best brains in science are only ,just beginning to understand the miracles that one tiny living cell can perform.
The skin on the tip of your finger is made frown about 5 million cells, and when you get a scratch, remember that there are about 5 million cells in every drop of your blood. Most of the billions of cells in your body are living, and the dead substances of your hair and teeth were made by living cells. Every plant and animal is made from living cells of some kind.
The microscope enlarges living cells so that we can see them. A red blood cell looks like a saucer with a thick rim. A long muscle cell is tapered at both ends. A neerve ce11 is a thread, perhaps 6 feet long, with branched threads at each end. There are different types of cells in your body, but in some ways they are all alike.
Every living cell is a small factory which performs chemical wonders. The busy little workshop takes its orders from a small, dark speck called the nucleus. The chemical work is done by a tangle of the finest threads, tiny grains and granules, bubbles and drops of liquid which float in chemical baths of pale 3elly.
Each living cell is a small. Unit wrapped inside its own miniature world. A living plant cell is encased inside hard, boxy walls. A living ce11 in your body is wrapped in a cellophane thin membrane. This important mmbranr allows same chemicals to pass into the cell and others to pass out.
Digested foods and other liquid chonicals pass through the membrane into the cell. The busy workshop inside the cell uses all of these chemicals to rebuild itself and perhaps to build new cells. It changes sme of the food chemicals into energr so that you can move around. It turns some of the chemicals into fats to be stored and used later. These chmical chores leave wastes., just as a fire leaves ashes. These waste materials pass through the membrane, and other cells send them outside the body.
Some small plants and animals have only cells to do all their chemical duties. But each ce11 in your body leads a double life. It tends to itself, and it does some special duty to help the whole body. A cell in the starnach changes food into liquid chmicals. A nerve cell carries messages, and a kidney cell helps remove wastes from the body. Billions of these cells work together to keep your body in good working order.