It's called "chemistry"--the on-screen affinity between stars, the magic that simpatico performances and personalities can bring to celluloid.

Chemistry is what made Tracy and Hepburn so memorable--and chemistry is behind the success of one of TV's top series, says a member of the cast.

According to Bea Arthur, one of the quartet of stars in the series "The Golden Girls," the secret to the show's high ratings is the chemistry among herself, Betty White, Rue McClanahan and Estelle Getty.

Arthur, looking slender, fit and ready to return to work for the NBC show's second season, said unlike many sitcoms "The Golden Girls" did not go through the trial-and-error rituals of matching stars to see if they clicked.

"Four months before the show went into production my agent called and said she was upset that I was talking to (producers) Paul Witt, Tony Thomas and Susan Harris about a series," Arthur said, delving into exotic hors d'oeuvres at a Persian restaurant not far from her canyon home.

"I knew nothing about a new series. A couple of weeks before rehearsals began the producers called to ask me if I wanted the part.

"From what I understood, they had read everybody on both coasts for all leading roles. I read the script carefully. It was absolutely great and the characters were perfect.

"I knew on the first day of rehearsal we would be a hit, but I had no idea that it would become a breakaway smash. Even before we went on the air the critics proclaimed us a hit. I was afraid it might be a case of overkill."

The relationships among Arthur, White, McClanahan and Getty is thoroughly professional during readings, rehearsals and performances.

There is a little of the clowing around, joking and hijinks common enough on sets with mostly male performers.

Nor are the actresses close friends off the set.

"We see enough of each other during the long days we put in," Arthur said with a smile.

"The best thing about our relationship is there is no sense of competition. There is a total lack of ego.

"Each of us does what she can to contribute to the show. We don't improvise much because the scripts are so good. One reason the show is a success is that our writers are all under the age of 30.

"I've learned that a performer should never take a show because of its concept. Success has to do with the people you work with.

"I'll never forget doing the series 'Amanda's.' It was a takeoff on the English sitcom 'Fawlty Towers.' It was a good concept, with me playing a female John Cleese. The scripts were terrible and there was no chemistry in the cast."

Following on the heels of "Maude," Arthur was disturbed by the failure of "Amanda's" in 1983.

It was with great glee that she joined "The Golden Girls."

"Everyone tells me, Betty, Estelle and Rue how wonderful it is that we are depicting older women so favorably," Arthur said. "I never think about such things.

"Perhaps we have made people understand that older women are just like younger women. That's no big deal. Everyone knows that."

Arthur's new character, Dorothy, is as caustic and sharp-tongued as Maude, whom she played for six years. But Dorothy is softer, more feminine and infinitely more sympathetic.

"I'm 5-feet-9 1/2 and I have a very deep voice, so no matter what I play, I'll be the same," she said. "That won't change. But Dorothy is much closer to me as a person than Maude and just as much fun to play.

"I'm grateful to have been part of two major hits in television. That doesn't happen to many performers."

Arthur closed her eyes, raised a finger skyward and said, "Somebody up there is looking after me."