One of Dieterich Buxtehude’s (“books-tuh-HOO-duh’s”) 19 pieces in this genre was written in F-sharp minor on an organ tuned in Werckmeister (“VERK-my-stur”) temperament due to its unplayability in meantone. The left hand’s sixteenth-note ostinato speeds up to presto in the second half of an E minor Bach piece in this genre, BWV 855. Louis Couperin left note lengths to the discretion of the performer in his “unmeasured” form of this genre. 46 hymns like Vom Himmel hoch (“fom HIM-mul hohkh”) were set as the “chorale” type of this genre in the Little Organ Book. Arpeggiated ascending C-major chords open (10[1])a piece in this genre that (10[1])Charles Gounod (10[1])(“sharl goo-NOH”) quoted in his setting (-5[1])of Ave Maria. Bach paired pieces in this genre (-5[1])with fugues (10[1])in his Well-Tempered Clavier. For 10 points, name this musical genre that introduces another piece of music. (10[1])■END■ (10[2]0[1])