The laboratory is determining whether any American animals have mad cow disease.
Technicians carve out nickel-size sections from the brain stem medulla.
They chill them, bake them and treat them with a series of chemicals. There, peering at closeups of brain cells, the scientist in his lab coat stands lookout for a killer. While more than 180,000 cases of mad cow disease have been diagnosed in Great Britain since 1984, no case has been detected yet in the United States. American hamburgers remain as safe as ever. That may be luck.