The old lady's fits are supposed to be terminal, and all her children are doing their damnedest to help her die, but by golly she pulls right through for her hundredth birthday in a glorious entertainment called "Mama Turns 100," and with a little luck it will eventually be seen in American theaters.

Carlos Saura, the Spanish filmmaker, was in town for a reception in his honor last night at the Spanish Embassy, which is understandably proud of him in the international world of cinema, and "Mama" is his latest effort in a sparkling career of 20 years.

"Your actress, Rafaela Aparicio, doesn't look a day over 60, and what's more, she is so full of beans that nobody will believe all her children are trying to kill her," it was objected.

"No problem," said Saura.

Now that's the way to answer questions. You just take it on faith that she's 100, as you take a good bit else in (and out of) films.

"You know that house where the story takes place?" said Saura, referring to the marvelous old barn of a country house in which the film is set.

"Well, it's just out from Madrid and the land is fabulously valuable, and the estate is all tied up and nobody can do anything with it. And those people, friends of mine, are not only ready to kill Mama but everybody else, too. So I don't think it's implausible in the film.

"As you know, censorship was a problem during the Franco years, and filmmakers veiled things. the characteristers in 'Mama' were in an earlier film, with Mama representing the state Fernando representing the church, and so on. I've updated them 50 years is all."

"They're beautifully preserved," it was suggested, "and it's good to see that exiled Argentinean, Norman Brisky, playing the male lover even if he's bald. There are too many young guys."

"Of course there are," said Saura, who is in his late 40s. "Need more mature men. It's the best age, after all, for sex."

"Congratulations," he was told.

"No, I mean all of us, who are no longer mere boys."

Saura used to live with Geraldine Chaplin, actress daughter of Charlie Chaplin. She appears in the film, in which the husband is seduced right away from her by an outrageously pretty girl, Ampare Munoz. Now this Ms. Munoz, a former Miss Universe, according to all the best gossips, has in real life quite captured Saura himself, right away from Ms. Chaplin. Thus does life imitate art.

Saura is a slender man, whose early childhood coincided with the Spanish Civil War, a trauma the nation has been long in getting over, and a trauma that has affected Saura along with every other Spaniard.

His early films dealt in a veiled way with what he saw as the stifling effects of the Franco government, and his most recent ones have been sort of celebration -- it is not so much a question of mere survival now, but of understanding.

The Franco restrictions on films at least gave a secure frame, within which a filmmaker could protest as much as he dared. With censorship lifted, however (Saura said), the artist is on his own, and in some ways misses the security of his former prison.

Before he was a filmmaker, Saura was a photographer. His mother was a musician, his brother is a well-known painter, and both those arts appeal strongly to him. He likes to fly, he fidgets that he is so lazy and cannot do justice to the interests he has. he like mechanical things, he likes horses, he would like to study biology -- and the years keep racing past.

He won the Berlin Film Festival's Silver Bear for "La Caza" and Peppermint Frappe," and the Cannes special jury prize for "Cria Cuevos."

For years his producer has been Elias Querejeta, and Saura says "I don't have to know anything at all -- he knows how to do everything." He has never liked to make films based on scripts by others. He writes his own, or at least is a co-author of them. He is not a man who thinks in terms of trends -- something interests him and he makes a film. The pattern, if any, he will see looking back.

But back to the film which, after all, is fresher and more novel than the changing affections of mortal men. A stunning character is Fernando, son of Mama, who is a genuine nut. He keeps running long the ground with a glider on his back trying to get it to lift off, but it never does.

"Fernando represents the church," a reporter observed. "He's named Fernando for the Catholic kings, no doubt?"

"No," said Saura, "he's named Fernando because that's his real name. With actors it's easier to have their fictional names the same as their real names. When you yell at them, you don't have to stop and think."

"Well, your Fernando needs a technology, to get his glider to fly, that he simply does not possess. It's a hideous thing to say about the church," it was argued.

"Si," said Saura sadly.

"Still," the dialogue went on, "he does have this incredible closeness with Mama, representing the state, so they know each other's minds.Of course Mama advises him to shower -- I believe her words are "You stink' -- and he does look rather presentable there at the end. Though she rejects him for his part in trying to kill her. It's all rather complicated." r

"There's a lot of Fernando in all of us," Saura said, sitting very much at ease in the Watergate Hotel, and (unlike Fernando) natty in a turtle-neck, neat.

"He wants to fly but can't. Often I think of flying from a tower, floating and gliding, greeting friends . . . ."

"Ah, like Fellini," an excited film buff of extremely limited credentials cried.

"Not like Fellini," said Saura. "I'd do it my own way."

"And in any case," said an interviewer wanting to get rapport established again, after the unwise comment about Fellini, "you take showers."

"Oh yes," Saura said. Even so, he identifies with Fernando, the guy who was once an austere mystic sort of fellow, but who now seems content too study aerodynamics by turning an electric fan on a little model aircraft in his bedroom.

"When Mama has her fits and they pour down the lifesaving medicine, she certainly makes a lot of noise," it was suggested. "Anglo-saxons have terminal fits, too, but usually we just go 'tchuk' once or twice and keel over. The Spanish have great zest."

Saura said it's true, all his actors and actresses positivelys rejoice in flinging themselves about, including that Luchi, Mama's daughter, who goes quite berserk when she discovers that her daughter has been carrying on with a man.

The central wickedness of the film is this: The children propose to give Mama fake medicine when she has a fit, so that (denied of true medicine) she'll die.

But Mama knows what they're up to. It takes a mother to know her children, you know. Once, indeed, her son Fernando orates about the evil and filth of this world (he is in on the plot to kill Mama, for all his fine rhetoric) and is rebuked by Mama, who remindes him that so much that he sees as evil is merely "natura" -- fallible human nature.

In her triumphant scene, Mama descends from the ceiling in a throne garlanded with roses, and a splendid seat belt also of roses. Her fine fat legs and wiggly feet fairly twitch with delight at her 100th birthday.

"She looks rather like a bathosphere descending through the sea," it was suggested.

But it turns out her remarkable entrance to the party may derive from a festival Saura knows about in a Spanish town, in which the Virgin descends from the dome of her church to the singing worshipers below. The image and the analogy are not meant to be pushed to extremes. There is merely the hint, or the echo.

Some have said "Mama" is fine for Spain, but the humor does not translate too well, even with good English dubbed in, to other shores. But that is nonsense.

Every American has long known Mama, and Fernando with his dumb projects, and Luchi carrying on about how awful things are, and Anna getting caught in the trap set for badgers, and Antonio getting all confused with the pretty girl, etc., etc.

"The thing that bothers me," said a reporter, "is the ending, when Mama revives after her near-fatal fit.

"While she was seemingly unconscious, she has this vision of all her life, which she sees from a fast-moving train. She looks out the windows and sees the events of her 100-year life speeding past her. And she says life is so wonderful and there's so little left to her. And all that useless suffering, as she calls it, and all those needless sacrifices.

"Is that all she can say for 100 years? She could have said that much at 18," the arguer went on.

"Yes," said Saura, "I guess she could have. And if she lives to 200, I guess she can say it again."