Ron Rice, age12, of Morton, Illinois, for his question:

What is meant by cytoplasm?

Cytochemistry, cytolymph and cytoplasm are terms used in the study of the living cell. The branch of biology that specializes in cell study is cytology. The "plasm" in cytoplasm is repeated in protoplasm and both these words suggest jellified liquids, rich in nourish¬ing chemicals.

A cytologist interested in the cells of the liver may photograph a thin sliver of tissue magnified by an electron microscope. The liver sliver may be a tiny fraction of an inch in thickness. The picture may magnify its size 200,000 times. Photographs of this kind really show the detailed structure of living tissue. Other techniques, just as marvelous, are used to probe the chemical secrets that go on in the busy cells. There are plenty of fascinating careers waiting in cytology, the fabulous field of cell study.

One of the basic terms in this science is protoplasm. The protoplasm in that sliver of liver is a jellified substance arranged in cell units, each encased in a cell wall, some¬what like a clear plastic bag. The cell contains a small nucleus that acts as headquarters for all its activities. Between the nucleus and the walls, the cell is stuffed with a thick liquid mixture of chemicals that carry on the very processes of life itself. This substance together with the walls and the nucleus is called protoplasm.

Naturally we need a name for the miraculous mixture that surrounds the nucleus, filling most of the cell. It is called the cytoplasm. The mixture of chemicals differs somewhat in different cells. But all cytoplasm contains protein molecules of the elements carbon and hydrogen, nitrogen and oxygen. Many of these cells also contain atoms of sulfur or phos¬phorus. The basic ingredients of cytoplasm are atoms found in rocks and other non living substances.

Those enlarged pictures of the cell reveal that the cytoplasm is riddled with a system of channels, somewhat like miniature blood vessels. This system is called the ER, short for endoplasmic reticulum, meaning the inner cell network. Cytologists suspect that the ER is a transport system used to tote atoms and molecules from one center of activity to another. And the centers of activity within the cytoplasm are astounding.

There are tiny factories where molecules are changed to release energy. Other fac¬tories specialize in assembling assorted atoms into molecules. And there are messengers to carry instructions from place to place. These midget page boys are round balls called ribo¬somes. Thousands of them float in the cytoplasm of a living cell, carrying instructions form the cell nucleus. The cytoplasm also contains special proteins called enzymes. These act as factory foremen, speeding up manufacturing and making the chemical operations run smoothly.

Cytoplasm is indeed a miraculous world on a miniature scale. And modern cytology is just beginning to solve some of its secrets. It is made from ordinary atoms that are plentiful in the non living world. We do not know how these same atoms work so differently in the living cell. But our scientists are beginning to decode some of its wondrous chemical processes.