Will Augustus, Domition and Big Boy soon meet their deaths after being anesthetized and having their brains repeatedly probed by electrodes?

Or will the furry trio and their advocates in the animal liberation movement end up making monkeys of federal bureaucrats?

The three are members of the Silver Spring Six, a dwindling band of monkeys that were research subjects in a Silver Spring laboratory supported by the National Institutes of Health until they were taken away in 1981 when the lab was found to be treating the animals cruelly.

Over the past decade, the animals have become pawns in an emotionally charged battle over the right of scientists to perform medical experiments on animals.

Now, NIH scientists say three of the monkeys are in constant and incurable pain and should be euthanized. But the scientists want to perform one last experiment on them while they are in "terminal anesthesia." Scientists say the research could yield important new data on how the brain responds to neurological injury -- in this case the injury inflicted at the Silver Spring lab.

Medical researchers say the findings could be useful in treating human victims of stroke and accident.

Animal rights activists tried but failed to block the monkeys' deaths in the courts but the animals have one last chance: Five members of Congress are to make a last-ditch appeal next week to senior federal health officials.

The increasing visibility of the animal rights movement has prompted Health and Human Services Secretary Louis W. Sullivan to publicly condemn "terrorist" acts by animal rights groups against medical research facilities.

"It is important for all Americans to know that these attacks have the real potential to compromise medical research . . . and to stand in the way of significant medical breakthroughs," Sullivan said in a recent speech.

The six monkeys were among 17 freed by Montgomery County police in 1981 after a worker complained of their cruel treatment there.

Five of the 17 have since died, one was put to death in January after a further NIH experiment, five have been given to the San Diego Zoo and the remaining six are living at Tulane University's Delta Primate Center in Covington, La.

Last week, following a years-long legal battle, the NIH served notice it planned to anesthetize three of the remaining monkeys, perform one final experiment on them to and immediately put them to death.

NIH officials said the animals were in constant pain because of the tests performed on them years ago.

"Ironically, by prolonging the lives of the Silver Spring monkeys through a series of legal maneuvers, animal rights activists have unwittingly created an irreplaceable source of knowledge about how the central nervous system adapts to injury," Sullivan said recently.

People for the Ethical Treatment of Animals, an activist group, wanted the monkeys set free in a nature preserve.

But a federal court threw out the group's lawsuit on procedural grounds.

A second animal liberation group, the Physicians Committee for Responsible Medicine (PCRM), also sued the government, seeking a federal probe of the original research on the monkeys and a court order blocking their mercy killing.

But U.S. District Judge John Garrett Penn ruled June 28 that the data generated by their deaths would be medically useful.

On Tuesday, a federal appeals court agreed, turning down PCRM's appeal.

But the monkeys have one more chance. The government has now agreed to stay the mercy killing until next week, when the five members of the House of Representatives are to make their case directly to NIH Acting Director William Raub.