JIMMY DANDY Stewart's emotions spin from one extreme to another in ''Vertigo''

Jimmy Stewart

He made his childhood acting debut in a Boy Scout play. And for great swaths of his Hollywood career, James Stewart -- better known to audiences as Jimmy, since he seemed so approachable -- went right on playing Boy Scouts, wholesome, reasonable, aw-shucks kinds of fellows who stuttered and drawled and stood knock-kneed before the opposite sex. That's probably why Stewart remains such a revelation as sick puppy Scottie Ferguson, the acrophobic, borderline-necrophilic detective in Alfred Hitchcock's trailblazing study of sexual dysfunction. (Follow the straight line to ''Blue Velvet.'') Stewart's Scottie is sympathetic as he becomes attracted to an unfaithful wife he's hired to tail. He's moving when he witnesses her apparent death. He's creepy when he finds another woman he wants to make over in his dead amour's image. And he's genuinely frightening when he discovers his love object may have betrayed him -- all sweaty rants and shaking-hand-across-the-lip fury. It's a thoroughly modern, adult performance. Nothing gee-whiz about it. Scout's honor.