Patsy Sears, aged 12, of Tucson, Arizona for her question:

How does hair grow?

Hair is very popular in the animal kingdom. Any animal who grows hair can boast of being a mammal. He is sure to be a backboned animal. His young are fed on their mother's milk. There are a large number of hairy mammals And each seems to grow his own kind of hair,

Different types of hair are very interesting to study under the microscope. Magnified a few hundred times, it is possible to recognize the hair from a sheep, a camel or a rabbit. Though you need no microscope to recognize the hair of a porcupine. Yes, his quills are really horny, enlarged hairs:

The fuzzy wool of the sheep is covered with loose scales. These little scales cling together to form soft, wooly yarn. Rabbit hair is also very scaley. The long, silky hair of the camel is almost smooth.

And human hair is not too different from some animal hair. Each hair is either a round or oval thread. It too is covered with tiny scales, though these are too small to be seen except under a microscope. Each hair is a thread of lifeless cells which grows from a pocket embedded in the skin.

The root of each hair is a little sheath called a follicle. Follicle is coined from a word meaning a little pod, or husks The hair itself is a thread of dead, unfeeling cells. The follicle is not. You can clip a hair without feeling it,, Hut you certainly feel a tug at the root of a hair.

The follicle is a little factory for growing a single hair. It is nourished by its own small blood vessel. The blood vessel also carried away its waste material. It also has a gland for making oil. This oil is the hair is natural brilliantine. It seeps along the thread, keeping it moist, supple and shiny.

There is also a minute pocket of dye. Hair without this dye is a corny yellow color. The dye is a dark color. A lot of it produces black hair. Less dye produces various shades of brown and gold. And the follicle has nerve sells. These senaitive cells may order, the muscles around a hair to contract. This happens in animals when they are cold. The hair fluffs up to keep them warm. It can happen to you when you are scared stiff and your hair seems to stand on end, Nerve cells also control the blood vessels and the supply of food to the hair, .And they also Inform you when a hair is pulled out by the root,

Each and every hair, human or animal, grows from its own follicle„ A human hair may grow from a foot to six feet long, If you out the end it will grow in again from the flooto Sooner or later it is shed and falls out, Then a new length of hair grows in from the root to take its place.