e,
but repeated,--as is proven by the almost literal agreement of the
second phrase with the preceding one, _cadence and all_. Part III
agrees literally with Part I in its melodic formation, but differs a
little in the treatment of the lower (accompanying) voices.

In the theme of Mendelssohn's pianoforte Variations in E-flat major
(op. 82), which see, the design is as follows:--Part I is a period of
eight measures. Part II is also an 8-measure period, ending upon the
tonic chord of B-flat major (the dominant key), as first eighth-note of
the 16th measure; the following eighth-note, b-natural, represents what
we have called the Retransition (in its smallest conceivable form), as
it fulfils no other purpose than that of leading back into the first
tone of the First Part. Part III is _only a phrase_, and therefore
shorter than Part I; but it corroborates the _beginning_, and, in fact,
the entire contents of the First Part.

The plan of Mendelssohn's 28th Song Without Words is as follows:--First
number the 38 measures, _carefully_. The first four measures are an
introductory phrase, or prelude; Part I begins in the second half of
measure 4 (after the double-bar) and extends, as regular 8-measure
period, to measure 12. Part II follows, during the same measure; its
form is a period, extending to measure 20, and closing with a very
distinctly marked semicadence on the dominant chord (chord of D). Part
III is 14 measures long, containing therefore six more measures than
the First Part; its first phrase is almost exactly like the first
phrase of Part I; its second phrase (measures 25-28) differs from any
portion of Part I, but closely resembles the melodic formation of Part
II; its third phrase is based upon the preceding one (_not_ as
repetition, however), and is expanded to the 34th measure. The form of
Part III is phrase-group. The last four measures are codetta, or
postlude, and corroborate the prelude.

For exhaustive technical details of the Three-Part Song-form, see the
HOMOPHOBIC FORMS, Chapters 11, 12, 13, 14 and 15.

LESSON 10.--Analyze the following examples of the Three-Part Song-form.
The first step, here again, is to fix _the end of the First Part_; the
next, to mark the beginning of the Third Part, by determining where the
_return to the beginning_ is made. These points established, it
remains to fix the beginning of Part I, by deciding whether there is an
introductory sentence or not; then the end