GERSHWIN: "Porgy and Bess." William White, Cynthia Haymon, Damon Evans, Harolyn Blackwell, Cynthia Clarey and others; Glyndebourne Chorus, London Philharmonic, Simon Rattle, conductor. EMI Records. CDS 7 49568 2 (compact disc). This sumptuous recording presents cast members from the 1986 and '87 Glyndebourne productions, reunited under Rattle after concert performances in London. The fervor of the conducting and the contributions of most of the singers are never less than compelling. Rattle is stunning in his idiomatic mastery of the orchestra and the specially hired chorus. White is a touching Porgy and Evans a sleazily insinuating Sporting Life, but it is the women who come off best. Haymon creates a powerful characterization as Bess. Clarey furnishes a gripping "My man's gone now," but the vocal highpoint is Blackwell's langorous "Summertime," taken here almost as a Mahler Adagio.