The opening bars of the 'Charleston Theme' from George Gershwin's 1928 symphonic composition "An American in Paris" (as arranged by Conrad Salinger for the eponymous 1951 film for the Toulouse-Lautrec ballet sequence danced by Gene Kelly as Chocolat and Leslie Caron as Jane Avril), then the opening bars of Bix Beiderbecke's cornet solo on the 1927 recording of Howdy Quicksell's "Sorry," a portion of which Bix also played in the Goldkette Orchestra's recording of "Slow River" from earlier that year. 

bwascher