April 26, 1994

The quest begun by philosophers in ancient Greece to understand the nature of matter may have ended in Batavia, Ill., with the discovery of evidence for the top quark, the last of 12 subatomic building blocks now believed to constitute all of the material world. An international team of 439 scientists working at the Fermi National Accelerator Laboratory will announce the finding today, bringing nearly two decades of searching to a dramatic conclusion.

The leading exchanges for trading oil and gold futures consummated their on-again, off-again courtship last night as their members voted to merge. The New York Mercantile Exchange will pay more than $60 million to members of the Commodity Exchange of New York. The merger will enable the two exchanges to cut expenses by reducing duplication in computer systems and in the work force that handles marketing, accounting and product development.

The heirs of Richard M. Nixon plan to continue his 20-year-old fight to control more than 3,000 hours of White House tapes and 150,000 pages of Presidential papers, his lawyer said today. But legal experts said Mr. Nixon's death may speed the release of the records, which are locked away at the National Archives and have never been made available to scholars or journalists.

Bombs exploded across South Africa today, hitting mainly black taxi terminals and polling places in a crescendo intended to demoralize the new South African electorate on the eve of its first vote. A few hours after the worst attack, a horrific morning blast that killed 10 and sprayed human body parts and mangled minivans across a taxi park in suburban Germiston, the police said they were questioning a suspect and hoped for a breakthrough.

SHE was 69, and still active as a professor at Harvard University. But, she told a research team there, she had begun to find it hard to recall the names of newer faculty members, and not long ago completely forgot her classroom number when asking for a slide projector to be set up. Just that morning, she said, she was at a loss to think of the word for "the thing you turn eggs over with." She had one question for the research team, assembled to study the normal course of mental aging: "Am I losing it?"