A Diamond in the Ruff : A CALL TO ASSEMBLY: The Autobiography of a Musical Storyteller <i> By Willie Ruff</i> ; <i> (Viking: $24.95; 432 pp.) </i>

“A Call to Assembly: The Autobiography of a Musical Storyteller” is an unmitigated delight. In its account of a talented African-American’s Southern childhood, filled with sympathetic relatives and neighbors, it can hold its own with Alex Haley. In its episodic account of one adventurous spirit’s individualistic pursuit of knowledge and experience around the globe, it brings to mind the adventures of physicist Richard Feynman. And in its engaging prose, with its nice turns of phrase and witty grace notes, it inevitably suggests good jazz improvisation: rich in content, well-structured but full of surprise.

Willie Ruff’s may not be a household name, but the 60-year-old musician who doubles on French horn and acoustic bass has a solid reputation among jazz followers. He has played on classic recordings by Miles Davis and Gil Evans, and the duo that Ruff and pianist Dwike Mitchell founded in the 1950s is one of the longest-running acts in the business.

Creating jazz of enduring quality is but one of Ruff’s endeavors, however. Since 1971 he has been a professor of music at Yale. He has lectured and performed in Russia and China and made documentary films in Africa and Brazil, mastering various languages as necessary. His peripatetic adventures have impressed colleagues and inspired journalists. New Yorker magazine writer William Zinsser wrote a book about Ruff and Mitchell in 1984.

Now Willie Ruff has published his own book, a wonderful volume of memoirs that may well bring him more popular recognition than all his other activities combined.

The unique odyssey of Willie Henry Ruff begins in 1931 in Sheffield, Ala., just up the road from the town of Baptist Bottom. Fueling little Willie’s odyssey is the boy’s innate curiosity, a quality soon shaped into a love of learning by the grown-ups whom the youngster is eager to study. Ruff would be lucky with teachers throughout his life. “A Call to Assembly” is abundantly populated with loving guides and helpful mentors, from the banks of the Tennessee River to the halls of academe.

One of the earliest such counselors, a virtuoso horn player named Pete (The Poet) Lewis, tells Willie: “Always remember that music don’t mean a thing unless it tells a story. It’s got to say something. Now, you got a story to tell, and don’t you ever let nothing or nobody make you ashamed to tell it in music. . . .”

Ruff begins mastering his musical story technique in the Army, which he joins at age 14. While stationed at the all-black Lockbourne Air Base in Ohio, he comes under the stern baton of Chief Warrant Officer John Brice, an instructor-conductor determined to shape the base’s ragged aggregation into a first-rate symphonic ensemble. Also at Lockbourne, Ruff meets Dwike Mitchell, the pianist who later becomes his partner.

Ruff and Mitchell first work together in Lionel Hampton’s band before going out on their own. The duo’s creativity in seeking gigs leads to college concerts and to jazz-history-lecture performances for schoolchildren. Eventually Ruff oversees such ambitious events as the 1972 “Conservatory Without Walls” at Yale, which brings together a galaxy of African-American musical artists to honor the tradition’s living masters.

The jazz anecdotes in Ruff’s book are fascinating and feature such luminaries as Duke Ellington, Benny Carter, Charles Mingus and Dizzy Gillespie. But jazz is only one of several themes that recur throughout this autobiographical concerto. Black military history, the genealogy of sacred music and the origin of the hambone are others.

Ruff develops and interweaves these themes with great style. His interest in 16th-Century Italian church music begins in Paul Hindemith’s classroom and leads many years later to a solo French horn recital under the dome of St. Mark’s Cathedral. His knowledge of the black regiment that took San Juan Hill in the Spanish-American War, learned from Pete Lewis, first prompts a remarkable reunion of World War II veterans at a Hollywood director’s house, and then causes a joyous discovery in the basement of Yale’s library. Always Ruff sees things coming full circle, like the music of his own personal sphere.

Not that Ruff’s autobiography is all fond chuckles and glad celebrations. It’s an honest account of a life that begins in the segregated South at the height of the Depression, continues through service in a segregated military and goes on to encounter the roadblocks of racism. There are plenty of examples, both large and petty, of how segregation was rigidly enforced.

There are dozens of memorable vignettes in “A Call to Assembly” (a title that derives from an Army term). I’m partial to the one of Ruff and Mitchell dodging through Manhattan traffic, each carrying one end of Ruff’s bass, on their way circa 1955 to audition for the type of club owner whose hiring logic goes: “It’s simple rithmetic. . . . Just two (expletive) guys! They make as much noise as three (expletive) guys. Why keep paying three? Who needs trios!”

But the mean in spirit are far outnumbered, at least in Ruff’s account, by the kind and helpful (both white and black).

Such figures seem to rise from the pages and hover above Willie Ruff like guardian angels: Helen Keller and W. C. Handy, his hometown’s icons; a host of relatives, from his mother to his daughter Michele; surrogate relatives such as Daddy Long and Mrs. Minnie; father figures like Warrant Officer Frank Ruffin; tutors like Abe Kniaz. All teach (by word or deed) to honor tradition. Shaped by such as these, Willie Ruff--student, teacher, artist--extends the tradition and ably passes it on.

Readers! Heed this call to assembly, PDQ.