the middle portion of the movement lasts 48 bars and is also symmetrical in structure, made up of two fugal sections and a central episode in which the non-thematic material in the ritornello is heard again. the new fugue subject is five bars long and is first heard in the violin with a simple figured bass accompaniment in quavers. the subject is then taken up in the upper keyboard, while the violin part plays figures drawn from the continuo line, including characteristic quaver leaps in sixths. a two bar bridging passages with semiquaver scales in parallel thirds in the upper parts leads into the statement of the fugue subject in the bass line, while the upper parts develop the accompanying motifs in syncopated exchanges. at the close semiquaver scales in the bass merge into the semiquaver arpeggios from the second interlude in the ritornello, which is reprised in full with the upper parts exchanged. it is followed by a reprise of the first interlude, which leads directly into a repetition of the entire fugal section with the upper parts exchanged. this time at the close the semiquaver scales in the bass line are joined by parallel scales in the upper parts for the final cadence that heralds the concluding rendition of the ritornello.