The third and best volume in the author's ``science-in- fiction'' tetralogy (Cantor's Dilemma, 1989; The Bourbaki Gambit, 1994). Djerassi (Chemistry/Stanford) takes an upbeat view of the kinds of international scientific conferences so scathingly described by Arthur Koestler in The Party Girls. Here, Melanie Laidlaw, 35, a childless American widow, directs fund-giving by a foundation for reproductive biology. At a conference in Kirschberg, Austria, she falls in love with a 50-year-old Israeli nuclear engineer and policy wog by the name of Menachem Dvir. Dvir's wife, it happens, was paralyzed in an auto accident 20 years ago while he was driving. He's also infertile as a result of overexposure to radiation. Melanie, meanwhile, is tapped by a group that's pioneering in vitro fertilization and needs funds from her foundation. She has already had a second tryst with Dvir at a new conference, and it's there that the idea occurs to her of stealing her lover's sperm, having the needy in vitro group fertilize one of her eggs, and bearing his child without his knowledge. This leads Djerassi into a full-dress review of the early years of in vitro fertilization, while a review of Dvir's undercover ties with a PLO policy market is covered so thoroughly that one feels well informed about Middle East politics. Also, the nonreligious Melanie decides to have her son born to a Jewish mother and so undertakes confirmation as a Reform Jew, which Djerassi details in great depth. Will Menachem accept his son (or seed)? Djerassi fudges the obligatory Tolstoyan face-off between Melanie and Menachem, but leaves the reader satisfied despite this shortfall. A great novel? No. But absolutely strong and real. Bravo, professor.