Soak gelatine in cold water, beat whites of eggs slightly, add powdered sugar, and gradually hot cream, cook over hot water until it thickens; add soaked gelatine and remaining sugar, strain into a pan set in ice-water, add bananas and lemon juice, stir until it begins to thicken, then fold in whip from cream. Line a melon mould with lady fingers trimmed to just fit sections of mould, turn in the mixture, spread evenly, and chill.