G maj.
Compare this diagram, also, with that of the Third Rondo-form, and note, accurately, the points of resemblance and contrast.
Compare it, further, with the diagram of the sonatine-form, on page 122.

It will be observed that here the Recapitulation does not follow the Exposition at once, as there, but that a complete middle division intervenes, instead of the brief interlude or re-transition; from which the student may conclude that the sonatine-form gradually grows into the sonata-allegro form, as this interlude becomes longer, more elaborate, and more like an independent division of the design.

Or inversely, and perhaps more correctly, the sonata-allegro becomes a sonatine-design _by the omission (or contraction) of the middle Division_.
THE EXPOSITION .-- The presentation of the thematic factors, the statement or Exposition of the two themes and codetta, is made exactly as in the sonatine-form, though probably upon a broader scale.

The Principal theme is usually a Two-Part Song-form, at least; often Three-Part.

In broader designs, a separate transitional passage appears; in more concise designs, the transition is developed out of the last Part of the Principal theme by the process of dissolution--as will be seen.