Pam Lee, age 13, of Enid, Oklahoma, for her question:

What material is a snail's silvery trail?

This topic is not for the squeamish ones. There are many people who look down their noses at the humble snail and many others who turn up their noses at the thought of all slippery and slimy creatures. This is too bad because more information about the snail's silvery trail may help us    finally    to master the sniffly cold.

The snail is classified as a gastropod because his one and only foot is a pliabla, leathery muscle on the underside of his stomach. The term “Gastropod" is coined from two older words meaning stomach and foot. It travels naturally at a snail's pace, by mak¬ing wavy motions along his muscular foot. But the ground and  the grasses are too rough for the sturdy foot to slide smoothly along. To overcome this handicap, the snail sec¬retes a slimy mucus substance as he goes. The foot slides smoothly along on top of it, leaving a silvery trail of used mucus behind him.

Mucus substances are very common throughout the animal world, more so than most people think. Certain fish ooze slimy mucus to feed their young and other sea creatures secrete mucus to attach themselves to solid objects. In some cases, slimes and mucus secretions act as protective coatings and some biologists suspect that they may help to seal out germs.

Many people may be surprised to learn that their own bodies could not carry on digestion and other vital process without normal secretions of mucus. We have mucus glands in the lungs, the intestines a»d many other parts of the body. When you get a cold, excess mucus is produced, causing coughes and sneezes.

Mucus is made from biochemical materials called mucins. And mucins contain assorted mucopolysaccharides, mucoproteins and neuraminic acid. If you wish to probe deeper into these fancy nares, you will learn that the snail's silvery trail is a type of protein built from 15 different amino acids. Amino acids, of course, are the building blocks of the body's durable proteins. The mucin molecule is a combination of both a protein and a non protein molecule. The non p oteins may be amino sugars, sulfates or sugar acids. If your curiosity leads you to investigate the busy activities of all these strange sounding chemicals, you will be a qualified biochemist.

The simplest explanation is that a snail's silvery trail is composed of mucins and that mucin molecules are combinations of protein and non protein molecules. Researchers suspect that some of these molecules form long chains, or polymers. The polymers may form netted frameworks that hold the gummy, sugary substances of mucus.

Biochemists are investigating many unknown aspects of mucus in general. Researchers are trying to learn new ways to break apart its rigid polymer framework. This research may well lead to new medicines that reduce the overflow of mucus caused by bronchitis, pneumonia and the wretched little common cold. The slippery snail with his silvery trail, it seems, might possibly teach us how to cure the sniffles.