The stage of the Terrace Theater was dark and completely empty for the final number of last night's concert, and the music was the best in an evening of fine music-making.

The concert was a memorial for Leonard Rose, the great American cellist who was born in Washington in 1918 and died of leukemia in New York last November. After spoken and musical tributes by his friends and colleagues, the evening's conclusion was left to Rose himself, via a tape recording. He was heard joking with the audience, praising other cellists and playing Faure''s "Ele'gie" at the first American Cello Congress, held several years ago at the University of Maryland.

The "Ele'gie" was an encore, after a standing ovation that had been led by Mstislav Rostropovich in the audience. Speaking impromptu at the congress, Rose called Rostropovich "the greatest cellist of our generation" and then asked him to play the piano accompaniment for the encore, which was dedicated to the memory of Pablo Casals. When Rostropovich hesitantly sat down at the keyboard, Rose turned to him and asked, "Slava, how should we play -- too fast or too slow?" and then the unrehearsed performance began at exactly the right tempo. The pianist sounded a bit tentative in the opening measures but warmed up quickly and was soon an equal partner in a performance to be long remembered. The cellist was, in the usual Rose style, impeccable.

Rostropovich could not attend last night's memorial concert, but his tribute to Rose was read by George Moquin, executive director of the American Cello Council. He had admired Rose, he said, not only as a friend but as a man with "a great depth of honesty and integrity . . . a totally uncompromising musician for whom only one ideal existed -- music."

Rostropovich recalled Rose's invitation for a visit during his final illness: "Come say goodbye, but don't forget to bring champagne."

"I was shaken by his calm acceptance of death," Rostropovich wrote.

Marta Istomin, artistic director of the Kennedy Center, a fellow cellist and a friend of Rose for a quarter-century, said practically every outstanding cellist in America today was a student of Leonard Rose. He was "a complete musician," she said ". . . a brilliant cellist, a devoted teacher, an artist."

Stephen Kates, a student of Rose and the president of the New York Violoncello Society, recalled him as a teacher who always made his students "dig a little deeper." Then he played Schubert's "Arpeggione" Sonata with a rich, creamy tone, a technical brilliance and an intense emotional involvement that showed how the spirit of Leonard Rose lives on in his students.

David Popper's "Requiem" for three cellos was eloquently performed by Robert Newkirk, David Premo and Daven Jenkins. But the highlight of the evening's live music-making was the haunting "Bachianas Brasileiras No. 5" of Heitor Villa-Lobos, performed by soprano Phyllis Bryn-Julson with eight cellists of the National Symphony: John Martin, Steven Honigberg, David Teie, Dorothy Stahl, Glenn Garlick, Janet Frank, David Howard and David Hardy. All were students of Rose, of his students or of his teacher, Felix Salmond.

The performance was outstanding. Bryn-Julson's voice, cushioned by the gentle sound of massed cellos, soared ecstatically in the rhapsodic first movement and executed the vigorous dance rhythms of the second movement with perfect control. John Martin contributed some beautifully phrased solos. After that, only the voice and the cello of Rose himself could have brought the evening to a greater climax.