Stuttering, which affects about 1 percent of the population, is a speech disorder originating in childhood, between ages three and five, thought to derive from parental pressures for fluency. Jonas' casual inventory of the historical and current theories for this puzzling disorder is also an unobtrusively personal chronicle: although his stuttering disappeared during adolescence--as it does for four-fifths of those afflicted--he recalls the pain, frustration, and verbal detours of those years, and his experiences are among those offered as evidence. Until the 19th century, stuttering was generally regarded as a physiological problem which would respond to tongue therapy or surgical modification--often with monstrous results. Since then, dozens of explanations have been suggested and rejected, and modern speech therapists (including a disproportionate percentage of stutterers) have favored Johnson's diagnosgenic theory (parental misapprehension) and Van Riper's Iowa therapy (smoothing the stutter) without seriously examining other possibilities. Jonas investigates the most recent experiments--using conditioning, electrical stimulation, cybernetic theory--and underscores Penfield's dramatic discovery that ""there is no single spot in the brain where the elements of speech axe compactly stored"": speech is a complex, coordinated function which continues to baffle the experts. An affecting, informed, deliberative essay enlarging on a recent article in The New Yorker.