In 1938, Jelly Roll Morton was near destitute. Ten years earlier, the New Orleans-born Creole pianist had been a major star, a bandleader and composer famous as one of the formative figures of the jazz age. But times changed, and so did tastes in popular music. Even though many of his tunes, like “King Porter Stomp” and “Wolverine Blues,” were played by swing bands all over the country, Jelly Roll (1890-1941) was reduced to working in a little club in Washington, D.C.

There he attracted the attention of a small group of local jazz fans and vintage-record collectors who rejected the “commercial” swing music of the day in favor of the more “authentic,” earlier New Orleans style. Morton eventually came into contact with Alan Lomax (1915-2002), who ran the Archive of

American Folk Song at the Library of Congress. Not a jazz lover himself, Lomax was initially interested in documenting Morton’s recollections of pre-turn-of-the-century New Orleans folk tunes. But when he turned on his 78-RPM disc-cutting machine, he tapped into the mother lode of American music history.

As Jelly Roll Morton told his own story, he brilliantly commingled it with a vivid account of the origins of jazz in New Orleans. In a deep, smooth monotone, he told of traveling across the country in the wild-and-woolly days when jazz was still exclusively a Southern thing, and a black thing. He recounted his life not only as a musician but as a gambling shark, a con man, and a pimp. Most of all, he told everyone how great he was, claiming to have invented jazz virtually single-handedly, and seeking to back up his claims by providing dozens of examples on the piano. Lomax caught it all in eight hours of interviews on roughly 100 12-inch sides of shellac.

These recordings have been issued in dribs and drabs. In 1947, jazz fan Rudi Blesh issued excerpts in a series of 78s on his Circle Records label. In 1959, jazz fans Orrin Keepnews and Bill Grauer issued 12 LPs on their Riverside Records label. There have been compact discs of the material, too, but the new box set, “Jelly Roll Morton: The Complete Library of Congress Recordings by Alan Lomax” (Rounder 611888) marks the first time every note and every word have been made available.

The new set – a deluxe eight-CD box, shaped like a grand piano – also includes a new edition of the book that, after World War II, Lomax shaped from all this material (supplemented by interviews with other musicians from Jelly Roll’s generation). “Mister Jelly Roll,” first published in 1950, is the single most essential book ever written on jazz.

Part memoir, part formal biography, part portrait, part history of New Orleans, it warmly romanticizes the Crescent City in the fin-de-siecle period. No reader can come away from “Mister Jelly Roll” without feeling a deeper love for early jazz. (The marvelous illustrations of David Stone Martin, who would go on to become the house artist for practically all of jazz, are supplemented in the new edition with drawings by R. Crumb.)

Lomax once called Morton a “Creole Cellini,” and like that Renaissance sculptor, Jelly Roll was eternally unrepentant, reveling in his deeds and misdeeds. As a pool shark, he played a deadly game with a notorious gentleman whose two compulsions were gambling and serial killing; as a professional card player, he fleeced unsuspecting laborers of their paychecks. He sold phony patent-medicine TB cures to suckers in Mississippi, and had to leave town in a hurry after a child died. Indeed, the only time on the Lomax recordings that Morton expresses remorse is when he speaks of having beaten a horse he was riding in a parade.

Jazz’s great anti-hero brought the same “sharpshooter” mentality, as his friend Willie “The Lion” Smith called it, to his music. Morton brags of how he would travel to one town after another (St. Louis, Memphis, Chicago), find out who the local keyboard champ was, and, without letting on who he was, take the unsuspecting guy by surprise.

Yet Jelly Roll was also a supreme musicologist. He explains in convincing detail how an old French quadrille evolved into the jazz standard “Tiger Rag.” He reminds us of the importance of “the Latin tinge”: Without it, he insists, one can “never have the right seasoning, I call it, for jazz.” He takes us step by step through the creation of jazz – which he achieved, he said, by forging ragtime with the blues – and he spells out the concepts of syncopation and swing. He also explains, among other things, that ragtime was a specific body of compositions, whereas jazz was a style that could be applied to any tune.

These recordings are an American treasure for the piano solos alone, but they also show Morton to be one of the great male blues singers. Though Morton had sung on a handful of his 1920s records, that aspect of his talent came to the fore here (and, thanks to the Library of Congress and Rounder Records, we can hear his voice with proper pitch correction and noise reduction).

A surprising amount of the previously unheard vocal material here concerns the same subject matter that Robin Williams addressed at Jazz at Lincoln Center’s recent benefit for hurricane victims: the Crescent City as the original girl gone wild. There’s Jelly’s infamous “Winin’ Boy Blues,” in which he brags of his sexual prowess. The “Murder Ballad” climaxes – forgive the expression – in a sex scene at a women’s prison. “The Dirty Dozens” is his insult song, which delineates at some length the lifestyle of the mother of the person he’s speaking to, specifically her failure to wear undergarments. “Make Me a Pallet on the Floor” describes the sexual act in vivid detail for 17 minutes and 19 choruses – which, for most of us, unfortunately, is longer than the act itself.

Thanks to Lomax, Jelly Roll would become one of jazz’s great oracles. Now we can listen to him directly as he talks about such Louisiana traditions as social societies, and even guides us through a classic New Orleans funeral – the band would play the joyous “Didn’t He Ramble” on the way back, turning the funeral itself into a parade. Jelly Roll himself would ramble all over the map until the butcher cut him down.

wfriedwald@nysun.com