The Allegretto quasi Andantino sits in the position of a 19th century sonata's dance movement. Its ABABA design is in the tradition of the Beethoven symphonic scherzi, including the sharp contrast between sections: A is a pastorale/menuet(?), and B is an agitato/galop(?). Brahms also hints at a Schubertian Ländler with the leap to and from ^6 in bar 2:
Note, however, that the harmony is viiø7, not V9. In fact, the piano reduction has left out a note: a continuing G3 in the bassoons, of course confirming the pastorale topic.
There is a proper V9 in bar 22 (boxed in the first graphic above), but no simple resolution of the 9.
The pattern continues in the variation of the theme at the beginning of the B-section and in the first reprise of A.
The same is true of the F#-major reprise (circled), but leading into it is a very expressive V9 (boxed), where the 9 is resolved internally in a gesture one finds in Schubert waltzes and also in Brahms's hommage to them, op. 39.
In the ending, another brief moment of a root-position V9 (circled) is undermined by a chromatic descent and ascent. And a big invitation to what was by the 1870s a cadential cliché--V9/V--lacks its bass and so is another viiº7 (boxed). Brahms sets up the conditions so well that one wonders if the bass players thought they had been given the wrong note.
We'll find the situation somewhat different in the Waltzes, op. 39, but in general Brahms was more conservative than his best-known contemporaries in his treatment of the major dominant ninth and the upper tetrachord of the major key.
