/2-20). This ends the Exposition.

_Interlude_, the remaining beats of measure 20; it is, of course, a
brief re-transition, and is therefore strongly suggestive of the First
Rondo-form, the _details of which exactly coincide, thus far, with the
above factors of the sonatine-form_. Such coincidences merely confirm
the unbroken line of evolution, and are to be expected in the system of
legitimate, rational music designs. The RECAPITULATION (the original
_da capo_) follows, beginning with the

_Principal Theme_, B-flat major, as before (21-28) but somewhat
embellished. Again, there is no Transition. (Here the similarity to
the First Rondo ends.)

_Subordinate Theme_, corresponds very closely to the former version,
but transposed to B-flat major, the principal key, and variated (29-39).

_Codetta_, also in B-flat major (39 1/2-40), slightly extended. There
is no coda.

LESSON 16.--Analyze the following examples of the sonatine-form, in the
usual exhaustive manner:--

Beethoven, pianoforte sonatas; op. 10, No. 1, _Adagio_.

Op. 31, No. 2, _Adagio_.

Mendelssohn, _Andante cantabile_ in B-flat major (pianoforte).

Mozart, pianoforte sonata. No. 17, _Andante amoroso_ (somewhat longer
interlude).

Mendelssohn, _Presto agitato_ in B minor for pianoforte (preceded by an
"Andante cantabile" which has no connection with the sonatine-form of
the _presto_, but may also be analyzed). This design is very broad;
each factor is expanded to its fullest legitimate extent, especially
the "codetta" section.

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CHAPTER XVII. THE SONATA-ALLEGRO FORM.

ORIGIN OF THE NAME.--The fully developed Sonata-allegro form is the
design in which the classic overture and the first movement of the
symphony, sonata and concerto are usually framed. The student must be
careful not to confound this musical form with the _complete_ sonata of
three or four movements. It is not to be called the "sonata form," but
the "sonata-allegro form." It is to one movement only, generally the
first one, which is (or was) very commonly an _allegro_ tempo in the
sonata and symphony, that the present design refers; and its name,
sonata-allegro, is derived from that old historic species of the sonata
which consisted originally of but one movement, generally an _allegro_.

THE SONATA-ALLEGRO FORM.--As distinguished from the sonatine-form, with
its two Divisions, this larger species, based upon precisely the same
structural idea, has _th