Director George Abbott

''You forgot your cross, Junior!'' bellows a strong voice from the depths of the darkened Kennedy Center Opera House. The man who plays Junior, Dutch actor Lara Teeter, jumps as though a bucket of cold water had been dumped on him. ''All right,'' he promises the owner of the disembodied voice, director George Abbott, and continues the scene as though galvanized. The next time they run through this classroom scene in the revival of the '30s musical ''On Your Toes,'' Mr. Teeter does his crossover as though his life depended on it.

If there is a ''megalegend'' in the theater, George Abbott is it. Just hitting his stride at 95 after 70 years in the theater, Mr. Abbott has ambled up from his home in Miami Beach to direct the musical hit he first collaborated on with Richard Rodgers, Lorenz Hart, and choreographer George Balanchine in 1936. He is the ''Mr. Chips'' of the Broadway musical, the benevolent despot who's taught generations of hoofers, singers, and actors what it takes to make a show-biz hit. He's had a string of them, as coauthor and director of ''Damn Yankees,'' ''The Pajama Game,'' and ''Three Men on a Horse,'' and as director of ''Pal Joey,'' ''Sweet Charity,'' ''On the Town,'' ''Call Me Madame,'' and ''A Funny Thing Happened on the Way to the Forum.'' There are four Tony Awards among them, as well as a Pulitizer Prize for Drama for coauthoring and directing ''Fiorello!''

At this moment, the legend is sitting bolt upright in a red plush seat, his chin propped in his left hand as he watches the stage. At one point, dancers drift on stage in Arabian Nights costumes for the ''La Princesse Zenobia'' ballet built into this Depression-era musical. But nothing happens. Mr. Abbott booms, ''What's holding things up?'' and the number vrooms into action as though the starting flag had dropped at the Indianapolis Motor Speedway.

Mr. Abbott, as he is invariably and respectfully known in a world that turns on first-name coziness, is famous for the fast clip of his productions. But it's not so much their speed as their antic vitality. He is also very much in charge, not just of the ambiance of the production, but of the nuts-and-bolts stuff. When the chorus heads for the door in a huge clump, delaying their exit line, Mr. Abbott whisks them off with a piece of salutary common sense: ''Let 'em go out the side entrance. They don't all have to go out the door.''

When a direction is not heard and acted on promptly enough, Mr. Abbott rears up out of his seat and does a soft canter down the aisle toward the stage. He is a tall, emphatic-looking man who walks with a slightly Groucho Marx tilt. This day he is wearing a cream-colored turtleneck, light-blue pullover sweater, medium-blue corduroy trousers, brown leather shoes, and a determined expression.

This vintage musical is a romp about a hoofer named -Junior Dolan (Teeter) who has forsaken his vaudeville family's past to teach music, but is lured back to Broadway by a jazz ballet and its exotic Russian ballerina. There are romantic plot complications, of course; Junior is already in love with a sweet student from his music class, where a Works Progress Administration poster and photo of FDR remind us that this is the kind of bouncy show that cheered people up during the Depression.

In its present revival (the original production starred Ray Bolger as Junior) ''On Your Toes'' opened with the acclaimed Russian ballerina Natalia Makarova in her first musical comedy role, George S. Irving as the ballet impressario, Dina Merrill as its wealthy backer, and George de la Penna as the ballerina's partner. (Miss Makarova was to have danced for two weeks, but her brief hospitalization following a backstage accident hastened cast changes. The Kozlovs, a Russian ballet team, were scheduled to step into the ballet roles early this month.)

Through it all, the ringmaster of this landmark musical remains imperturbable. He's done it before. When ''On Your Toes'' opened, it was the first Broadway musical to incorporate ballet, teaming Abbott and Rodgers and Hart with classic ballet choreographer George Balanchine (also called in for the revival). The result was the sizzling jazz ballet ''Slaughter on Tenth Avenue,'' the high point of the production, which today still eclipses even the nostalgic numbers like ''There's a Small Hotel.'' Junior and his girl Frankie (Regina O'Malley) have just finished warbling that number when Kennedy Center chairman Roger Stevens appears in the gloom of the aisle, looking tall and straight as an obelisk in a business suit. His hands in his pockets, he watches the stage for a moment with a pleased smile, then asks Mr. -Abbott nonchalantly, ''Costumes arrived yet?'' Mr. Abbott, equally nonchalant, nods yes. That night is the first preview show; opening night is only four days away. This is the sang-froid of the seasoned pros.

When the actors take a break, Mr. Abbott chats about his first century in the theater. Across a bare brown desk in a rehearsal room he talks about temperament in the theater and how he handles emotionalism. ''I think it's exaggerated. I think you'll see just as much temperament among bricklayers who throw down their tools in anger as from an actor who goes flaunting to his dressing room. It's just that people think it's so ridiculous that you get angry over how you say a line or who gets the curtain call. It seems so petty, and it is - but the emotion is no different.''

George Abbott, who has a reputation for moderation and equanimity, talks about how he's avoided the pitfalls of temperament in his own life: ''I had a religious mother, and while I'm not religious myself, I think that training never left me, and that feeling that love is important and hate is to be avoided.''

He was born in Forestville, N.Y., then segued to Salamanca, N.Y., as a child, when his mother's parents backed his father in a wholesale tailoring business. While his father wasn't cut out for that business (which failed), he did succeed in politics as two-time mayor of Salamanca. With the help of a political appointment as a state government land agent, his father bundled the family off for what was then the Wild West - Cheyenne, Wyo. Back in Hamburg, N.Y., several years later, George Abbott had a high school career straight out of a Hollywood musical, being captain of the football team and voted ''most prominent actor.'' He dazzled them with his footwork in hockey, baseball, and track.

At the University of Rochester on a scholarship, he was determined to be a journalist. ''I was inspired by my mother, I guess, as so many are, who thought I ought to be a journalist 'cause I was good in what's called 'English' and not good in anything else. It was the only spark she saw.'' He smiles disarmingly. But in his junior year he wrote a farce, ''Perfectly Harmless,'' and when it was produced by the university's dramatic club, he was hooked by the footlights. In 1911, with his BA from Rochester, he opened at Harvard in the celebrated play-writing course taught by Prof. George Pierce Baker.

His one-act play, ''The Head of the Family,'' was produced by the Harvard dramatic club. Then he won a $100 prize in a contest sponsored by the Bijou Theater in Boston for another one-acter, ''The Man in the Manhole,'' based on a stint working in a steel mill. After a year at the Bijou as author, gofer, and actor, he struck out for Broadway: ''It occurred to me I could learn something about the theater and also make a living as an actor while waiting for my great plays to be picked up,'' he says with a flick of self-depreciation.

Was it the glamour of the theater that attracted him?

''Not in the sense that you mean it, at all. The excitement of the theater, I'd say more. Well, acting seemed to me the greatest fun in the world. I didn't see how it was rational for a person to make a living doing that thing. I thought, well, you have to make a living by work.'' But once he found he could make a living by having fun there was no exit for George Abbott.

Even in his first role, that of a drunken college boy in ''The Misleading Lady'' in 1915, he received good notices that made him feel he'd conquered Broadway. But it was a full 10 years - 1925 - before he had his first hit as a playwright, with ''The Fall Guy,'' written in collaboration with James Gleason. That was the beginning of his shooting-star career as a writer-director, launched with ''Broadway'' in 1926.

Drama critic George Jean Nathan said of Abbott in the '30s, ''His is the theater of snappy curtain lines, wisecracking dialogue, . . . sentimental relief in the shape of young lovers, and various analogous condiments, all staged as if the author had used a pepper shaker in lieu of an inkwell.''

A glossy photo of Mr. Abbott in early midcareer, in 1940, shows a genially handsome man, dapper in a pin-striped suit, with a full head of hair. He could pass for a matinee idol of the time as well as Mr. Boffo of the Broadway producer-directors. ''I used to be a blond when I was younger,'' he says. Today he has a gleaming pate, fringed by hair as white as goose down. His is a face made for sculpture: strong, bold lines, a prowlike nose, laugh parentheses around the mouth, a high-domed forehead with the enduring patina of polished ivory.

There is something about Mr. Abbott that is reminiscent of the stage manager in Thorton Wilder's classic piece of Americana, ''Our Town.'' He, too, has seen everything in town, knows everyone in town and how it all will turn out in the end. And he comments on it all with a terse, dry, Yankee wit that almost camouflages a knowing heart.

The man who's been described as the dean of Broadway theater and the ultimate ''play doctor'' has a reputation for knowing how to turn a flop into a hit. How does he do it? ''I think I'm a logical person. I think I see, when I see a play, what its faults are as far as construction. A great deal of the work done is to clarify the story, which is muddled.''

Is that what he did with the original ''On Your Toes''? ''Well, I was one of the coauthors of the original, but then I left them because they didn't start on time.'' (He simply frisked back to his home in Palm Beach, telling Rodgers and Hart he couldn't hang around any more.) When the play bombed in a Boston tryout, Rodgers called and insisted he come back. ''As soon as I looked at it, I knew what was the matter with it.'' According to Rodgers, Abbott said: '' 'Oh, come on, let's go out dancing, I'll fix it in the morning.' ''

A question about the differences between this production and the original is met with a cool blue look. ''Uh, I don't think I want to tell you.'' He pauses for a few beats. '' 'Cause it's the book, and that's just like bragging. It's more compact. It's the same story, same show, same music, same plot.''

The script, which in musicals is called the book, is ''all-important,'' Abbott says. ''It never used to be. If you read the book of the plays that were written for Gershwin and that era, they were childishly written, silly plots, unmotivated scenes to get in a joke, very bad. And I think 'On Your Toes' was maybe the first step upward, although not enough of one. I had to rewrite it this time.'' Extensively? ''Yes. I threw out three sets. In those days, if we wanted a song that mentioned a park, you had to have a Central Park set, and then we sang songs there. . . .''

With seven decades in the theater behind him, is it possible that Mr. Abbott still gets the jitters on opening night? '' 'Jitters' is not the right word. You certainly get very apprehensive and tense - but calm, in that you've done your work and the rest is inevitable, or at least you hope you've done your work. You find out afterward you haven't, sometimes.'' By a week after that rehearsal, the play has opened and Mr. Abbott has given the show pace and tang.

He is a sort of gravy master of this Broadway musical; he smoothed out the lumps, made it flow. Still, Washington Post critic David Richards calls it a benign, authentic revival that lacks excitement.

Mr. Abbott takes it all philosophically. That's how he dealt with the criticism of ''Tryout,'' his novel that he says was about Palm Beach, but which the publishers advertised as being about the theater. ''But anyhow, since it was a failure, I've almost forgotten it. That's a very convenient way'' of dealing with it, he says, and laughs.

He's equally sanguine about laurels. His reaction to being applauded this December as one of the Kennedy Center honors recipients for lifetime achievement in the performing arts: ''I thought it was nice. I thought it'd be pleasant. It was kind of exhausting in the middle of rehearsals to take two days out, (but) they certainly treat you right on that award. They take care of you like a baby.'' For this grandfather, being babied included a glittering reception at the White House, where even the President called him Mr. Abbott: ''I don't dare call him 'George,' because I am temporarily between jobs.''

Music man George Abbott manages to see a lot of contemporary Broadway hits between his gigs in Miami Beach with the orange trees he raises, the golf he plays, and the mambos he dances. Currently he likes a great many shows, among them ''Nine,'' ''Cats,'' ''Dreamgirls,'' and ''Sophisticated Ladies.'' He has special praise for Hal Prince, whom he considers ''a beautiful director,'' although their styles are different. ''His tastes are toward what you might call the mental theater, the idea theater; mine are toward the emotional theater, making people either feel comic or tragic.''

Finally we talk for a moment of the effect of movies and TV on the stage. Mr. Abbott, who also directed films for Paramount in the '30s, thinks neither movies nor TV have had much of an impact on the theater in the last several decades:

''I think television has had a commercial effect, but not much of an artistic effect. The stage is still supposed to be a more sophisticated type of entertainment.'' Even with the advent of cable television, he is sure Broadway will always be the mecca for national theater. ''We used to have 24 to 30 shows on Broadway, now we have only a fraction of that, but we have Off Broadway, which is really the same thing. So you can't tell what the effect of those entertainments will be. But I think they will create a hunger for perfection and for contact with the performers.''