NEW YORK — Gunther Schuller, the leading proponent of the Third Stream movement fusing jazz and classical music, has died at age 89.

His son, bassist Ed Schuller, said his father died Sunday morning at a hospital in Boston.

Schuller began his career in the 1940s as a horn player with the Cincinnati Symphony and Metropolitan Opera, but his love of jazz led him to also become involved in New York’s bebop scene. He played on trumpeter Miles Davis’ seminal “Birth of the Cool” 1949-50 recording session.

In the 1950s, Schuller worked with pianist John Lewis of the Modern Jazz Quartet to bring jazz and classical music together in what he called the Third Stream.

Schuller composed numerous jazz and classical pieces, including “Of Reminiscences and Reflections,” which won the 1994 Pulitzer Prize for music.