to be a little longer (more
extended) than Part One. A concluding section (called codetta if
small, coda if more elaborate) often follows, after a decided perfect
cadence in the original key has definitely concluded the Part.

The following is one of the simplest examples of the Two-Part Song-form
(a German _lied_ by Silcher):--

[Illustration: Example 52. Fragment of German _lied_.]

The whole embraces four phrases, and might, for that reason, be
mistaken for a double-period. But the _strong perfect cadence_ at the
end of the first period (reinforced by the repetition), and the
contrasting melodic formation of the second period, so separate and
distinguish the two periods as to make them independent "Parts" of the
whole. It is not one "double-period," but _two fairly distinct
periods_. The first cadence (in measure 4) has again, strictly
speaking, the elements of a perfect cadence, but, like others we have
seen (Exs. 50, 51), too near the beginning to possess any plausible
concluding power.

A somewhat similar specimen may be found in the theme of Mendelssohn's
Variations in D minor, op. 54, which see. Each Part is a regular
period-form, with correct semicadence and perfect cadence. The problem
of "agreement and independence" in the relation of Part II to Part I is
admirably solved; it is a masterly model of well-matched Unity and
Variety, throughout.

For a longer and more elaborate example, see No. 6 of the Songs Without
Words, in which, by the way, the principle of enlargement by the
addition of an independent prefix (introduction) and affix (coda) is
also illustrated:--

First number the forty-six measures with pencil.

The first cadence occurs in measure 7, and marks the end of the
prelude. Part I begins in measure 8. In measure 11 there is a
semicadence, at end of Antecedent phrase; in measure 17, a strong
perfect cadence, which, in connection with the subsequent change of
melodic form, distinctly defines the end of Part I (period-form,
extended). Part II therefore begins in measure 18. In measures 21,
25, 29, cadences occur, but none conclusive enough to close the Part.
This conclusion takes place, however, in measure 34. Part II proves to
be a double-period. A coda begins in measure 35; its first members
resemble the first phrase of Part I. In measure 40 another section of
the coda begins, borrowed from the prelude. For exhaustive technical
details of the Two-Part Song-form, see the H