Nancy Johnson, age 12, of Columbia, Tenn., for her question:

WHAT DO TONSILS DO?

There are two masses of special tissue in the throat called "lymphoid" tissue. This tissue, covered with a mucous membrane, forms a right and left tonsil.

Lymphoid tissue forms white blood cells, called "lymphocytes," the germ fighters in the blood. Because of this, medical people believe that the tonsils help destroy harmful bacteria.

The throat is actually surrounded by a ring of tonsil tissue. The "palatine" tonsils are the best known. In human beings, a palatine tonsil can be seen on each side of the back of the mouth just above the throat and below the roof of the mouth.

When the palatine tonsils of children become badly infected, sometimes they almost block the throat. Many doctors then prescribe a tonsillectomy, which is the removal of the palatine tonsils.