One of the world's oldest ongoing scientific experiments is in a field near the University of Illinois campus -- a corn breeding test that began in 1896 and has now gone through 80 generations of the plant and produced a mountain of valuable data on the theory of selectivity.

Agricultural science is taken so seriously at the University of Illinois that the undergraduate library is built underground so it won't cast a shadow and deflect normal wind currents from the nearby university farm test plots.

The most coveted status symbol in the Corn Belt no longer is a hybrid corn sign along a fence row, advertising Pioneer, DeKalb, Funk's or other standbys. It is a cap on a farmer's head, emblazoned with a company logo. One firm, Golden Harvest Seeds of Clinton, Ill., takes it even farther. It gives out caps, jackets, scarves, ski caps, coin purses and pocketknives bearing the company symbol. Farmers love them.

One seed of hybrid corn will grow into a stalk as tall as 12 feet. Each ear of corn contains up to 800 kernels. But the kernels are not saved for replanting. Seeds are produced separately and sold each spring, mostly through an extensive network of farmers who pick up extra cash as seed dealers.

For years, farmers figured corn rows should be about 40 inches apart. It seemed natural because that was the approximate length of stride of a horse pulling a corn planter. The age of mechanization showed that corn would do just as well planted in closer rows, now sometimes 18 to 20 inches apart.