Lisa Harris, ale 7, of St. Catharines, Ontario, Canada, for her question:

What are fingernails made of?

Your fingernails and a pussycat's claws are made of the same material. So are a horse's clorspin` hoofs and a pig's dainty little trotters. So are a cow`s horns and the terrible talons of the eagle. Nails, hoofs and claws are hard and stiff. You would never guess that they are made of skin. But this is true. Actually it is a very special kind of shin made of dead, dried up cells.

Actually, a very thin layer of this material covers all of the skin. It is called the epidermis and usually cue donut notice it. But when we bet a bad sunburn, it peels off in dry flakes. Just below the base of each nail, there is a little factory called a matrix. The matrix manufactures lots and lots of epidermis material from dry dead cells. It packs this material in a hard layer and this is the nail that grows toward the tip of your finger.