From the chief pop-music critic for The New York Times: a full-scale, somber, though often rambling and disjointed, history of ""the blues""--the Mississippi Delta song-music which, via Memphis and Chicago, became a major influence on rock 'n' roll. Palmer is less interested in those influences, however, than in the development and survival of the blues themselves as a distinct, ""refined, extremely subtle"" art form: ""the story of a small and deprived group of people who created, against tremendous odds, something that has enriched us all."" So he begins with a detailed consideration of the African musics--primarily Senegambian and Congo-Angolan--that slavery brought to America. And by around 1900, the particular gritty, ornamented, percussive, guitar-based ""Delta blues""--a deep-South idiom created ""by the poorest, most marginal black people""--becomes identifiable. From that point on, Palmer studies his subject chiefly through long, sometimes overlapping close-ups of about two dozen ""bluesmen"" (some of whom were profiled in Peter Guralnick's more evocative, less rigorous Feel Like Goin' Home, 1971). Combining life stories with dense interviews and music/lyric analysis, he focuses most on: early, influential Charley Patton, with his harsh, deep blues; legendary Robert Johnson, adventurous, inquisitive, obsessed by voodoo; the Memphis-centered bluesmen who shifted into ""rhythm and blues""; and above all Muddy Waters, who, though essentially faithful to Delta tradition, was the key figure in the ""Chicago migration""--which, by 1950, had turned Delta blues into amplified, more commercial ""Chicago blues."" All the subtle vocal and instrumental variations on this increasingly electrified blues--and the writer/performers who made them--are discussed. Yet Palmer emphasizes the persistence of the basic Delta-blues features, despite the blues' seeming decline (in the rock era); and he winds up by celebrating both the survival of Muddy Waters (through European popularity and the recent ""blues revival"") and the continued vitality of the Delta/Chicago strain in the work of relative newcomers like Otis Rush and Sonny Seals. Impressively exhaustive contemporary-music history, then--but the edgy format here (constantly backtracking, often repetitious) will put off non-specialists; and Palmer's sociological drift tends to get lost in the somewhat unselective detailing. So: mostly for fierce enthusiasts and scholars--but some of the anecdotal material (sharecropper woes to wild recording sessions) will attract a more general pop-music/black-history readership.