THE FRESHWATER EEL

Aristotle believed that eels grew ""out of the earth's guts"" and in the Middle Ages it was believed that they were generated from horsehairs. The truth -- that both European and American freshwater eels travel to the Sargasso Sea to spawn -- is just as remarkable. Scientists' research into the elusive life cycle, the physiological changes that enable eels to move from salt water to fresh, and the female's solitary journey to an upstream home are described in nontechnical language -- marred only by accurate but completely unimaginative pencil drawings.