ONCE, IN Israel," said Sergiu Commissiona, music director of the Baltimore Symphony, "I was staying in the same hotel with another Rumanian conductor, Celibidache, whom I thought an extremely interesting, imaginative musician. He was, however, almost obsessive about preparation, going over every tiny detail again and again and sometimes killing spontaneity.

"Anyway, one day we met in the corridor - he was impressive looking, long hair, dramatic, handsome. I said, 'Hello, how are you? 'Oh, I'm dead tired, exhausted, I've had the most hectic week - 10 rehearsals and two concerts! And how are you, Comissiona?'

"'Oh,' I said, 'I'm worn out, bushed, I've had a very trying week - two rehearsals and 10 concerts!'"

The story, which he swears happened just that way, is a genuine clue to Comissiona's artistic personality. Quick and mercurial of mind and body, he appears to thrive on hyperactivity. "Though I'm going on 50," he says, "I still enjoy a breakneck pace. Of course, I need respite, I have to refresh myself, learn, study. But I prefer short holidays. And when I'm guest conducting somewhere, I don't like to come to the place of the crime a week before and stick around for another three days after the concert - I want to move on to the next. I'm a hit-and-run conductor. I enjoy the challenge."

When he left his Rumania for the first time in the late 1950s, Comissiona went to London to do some conducting for the Royal Ballet, Clive Barnes, then still in England, wrote an enthusiastic review of one of Comissiona's performances that carried the headline, "New Conductor Awakens Sleeping Beauty."

Since his arrival in 1969, he's also awakened the Baltimore Symphony - adding over 200 works to the repertory, including more than 60 by American composers. In the same interval, the number of subscribers has risen from 3,000 to well over 9,000.

Under his guidance, the orchestra, once considered a respectable provincial ensemble, has acquired a reputation as a "contender" in the symphonic big leagues.

Even in this jet ago, Comissiona must rank among the most peripatetic artists on the international scene. His concert with the Baltimore Symphony in an all-Russian program at the Kennedy Center on Friday will be just one stop on a personal itinerary this season that will include, besides his 60 concerts with the Baltimore, guest engagements in New York, Montreal, Vancouyer, Boston, Jerusalem, Birmingham (Engl.), Barcelona, Oslo, Gothenburg (Sweden), Buffalo, Rochester, Puerto Rico, Chautauqua, Ambler and Aspen.

Though there's no lack of able, not-yet-famous conductors his age of younger, Comissiona stands in the foreground. No one, least of all Comissiona, would claim that the Baltimore Symphony today is an orchestra of the topmost class, despite the strides it has made during his tenure. But the performances he wrings from these musicians often generate an order of musical excitement that no amount of added virtuosity would significantly increase.

He does it by being able to combine uncommon lucidity, rhythmic exactitude and architectural grasp with a feeling for lyricism, drama and passion. In a work like Elgar's "Enigma" Variations, for instance, which he led in Baltimore a few weeks ago, he let the brooding introspection of the "Nimrod" variation swell to its billowing peaks by the minutest of degrees. But in the blustery finale of the same work, he knew just when it was time to let the devil take the hindmost.

I recall a performance of Ravel's "Bolero" that turned this potboiler into a freshly minted masterpiece by sheer intensity of conviction. But I remember too a Haydn symphony that was a model of rococo ebullience and jucidity.

He also happens to be riveting to watch. A thick shock of black hair above black beetle brows and glistening, coal-dark eyes, along with a quizzical mouth, give him a mine ripe for the caricaturist. His physical style of conducting is a mixture of curvaceous caresses, understated beats, wisps of sharp gesture and commanding sweeps.

A few minutes late for a meeting recently, he was all apologies - he'd just come from a dental appointment. "An hour and a half in the electric chair, brrrr - I'm sorry if I'm smelling of all the medicines," he began. All the while he was gesticulating, mimicking the dentist, himself squirming under the drill, crinkling his nose at the medicinal odors. The whole talk was that way - a conversational charade. Body language, it's clear, is his native tongue.

He decided he wanted to be a conductor? In the cradle, it seems. "Truly, I never had another dream from earliest childhood," he said earnestly. "I never wanted to be a doctor, an engineer, a fireman - it was always conducting. I guess I was 6 or 7 when I first heard an orchestra live - I still remember the impression made on me by Enesco, and another Rumanian, Georges Georgescu, who was a pupil of Nikisch. But our home was filled with music. My mother was an amateur singer, she played and sang Schubert, Schumann all the time. The radio was on day and night with classical music. There was also a gypsy area nearby, and I used to sneak off to watch their weddings and festivals - the fiddling was fantastic, they could do astonishing things with up-bows."

Comissiona's father, an industrialist, was a bit removed from all this. He went along with the family's musical activities, but his own taste ran along more "pop" lines. "He was always bringing the children little presents - toys, candy, various treats. But one day when I was already in adolescence he astonished me by giving me some music. It was the 'Poet and Peasant' overture, reduced for violin and piano. I was ridiculously scornful - 'This music is junk,' I said, 'I don't want to play it.'

'He was terribly hurt, and I had a very bad conscience from this for years, especially after he died (I was 16 then). Many years later I once programmed this piece, I studied the score like mad and worked the orchestra to the bone over it - they thought I was insane. But the performance was one of my best."

He got his first crack at conducting in storybook fashion. As a youngster he'd studied violin, and in his teens he landed a second-fiddle post in the Rumanian State Trade Union Ensemble ('The Communists by this time had nationalized everything." he says). In the very first week the regular conductor took sick for a matinee, and Comissiona was asked to fill in. It was while he was still fiddling that he also first caught site of his future wife, Robinne, a dancer he spied from the orchestra pit.

In 1954, Comissiona took a conducting prize in a competition in Besancon, France, the first landmark on a path that was to lead to Covent Garden; to Israel, where he lived for seven years, became musical director of the Haifa Symphony and founded the Israel Chamber Orchestra, with which he toured the U.S. in 1963; to Sweden, where he was director of the Gothenburg Symphony for six years; and to Baltimore.

Comissiona has well-defined ideas on rehearsal procedure. "I think it is important to allow the musicians to play the music, not just to dissect it," he says. "Whenever I start work on a piece, I always begin with a complete run-through, with no stopping for corrections, just to have everyone get the feel of the whole. Then I go back and cut and cut, but here again, I try as much as possible to cut on the long phrase, so as not to interfere too much with the pleasure of playing.

"Besides, I feel the best corrections are the ones the players arrive at themselves. I tell them, you are as good musicians as I am, I don't have to tell you these things.Of course, this is an ideal, never fully realized. But I count very much on every player wanting to be first class - I'm no magician, I can't improve an orchestra by waving a wand, it can only happen when it's the desire of the whole ensemble."

Among the models Comissiona has held before him in his own artistic development, the most significant was Bruno Walter. "From Walter I learned that the two activities of being a musician and a human being could be truly 'The Magic Flute' was one of the turning points of my life - my wife Robinne can still remember that when I was courting her I spent more time talking about Walter than I did wooing her.

"But when I was about 25, I suddenly came to the realization that I wasn't a conductor at all, I was a conglomeration of influences - Walter, Enesco, Constantin Silvestre, others I admired. I'm not Comissiona, I told myself; I must stop this, I hate them all, out of me, out of me! I felt very empty for a while, and I became very strict and square for a couple of years - a Toscannini in the worst possible sense.

"At last I came to a place where I felt secure in my own ideas, and for the moment, at least, I feel that my work now reflects myself. You may like it or not, but it is Comissiona."

Comissiona has a dread of being pigeonholed stylistically, and has "always loathed the idea of being labeled, so I leaped at every opportunity for diversity."

The breadth of his Baltimore repertoire is reflective of this. So are the numerous commissions for new work Comissiona has spurred - Ross Lee Finney, Lukas Foss, Elie Siegmeister, Gunther Schuller, Roger Sessions, George Rochberg and Henri Lazarof have been among the recipients, along with Robert Hall Lewis, John Downer and Jean Eichelberger Ivey of Baltimore.

Comissiona believes that a conductor's physical movements have an effect on the players - that the "diriography" is important.

"I can see that when I'm judging young, inexperienced conductors in unfamiliar repertoire for a competition, and for each one the orchestra plays entirely differently. But I never 'practice' my gestures or think out what I'm going to do, it just comes, under the influence of the music. 'There's a spot in 'Enigma,' for instance, where I do a funny, crazy little thing," he said, making mincing, knitting gestures with his hands and fingers. "It's just that in this spot in the music, I always thought, how very English, they're chatting over cups of tea, she's crocheting maybe - and the image stuck with me."

Despite his globe-trotting, Comissiona feels bound to the Baltimore scene. "I just returned from two months of travels and I came home filled with such emotion - I realized once again that this orchestra, these musicians are my great love. I don't tell them that, I don't actually go out there and say, 'I love you' - most of the time they hear only bad things from me. But that is the way I feel."

The biggest roadblock to the Baltimore Symphony's continued progress, he believes, is the lack of a fitting home. "Not just a hall," he says - the orchestra plays most of its Baltimore concerts in the old, un-airconditioned Lyric Theater - "but a home of our own. In the Lyric, aside from its acoustical properties, we now must share with opera, ballet, musicals. We often must rehearse elsewhere, in schools, miserable noisy places. There are ambitious plans to renovate the Lyric, which would be wonderful, but things are moving slowly.

"I don't think the city was prepared for how good the orchestra became so quickly," he explained with a grin.