[Illustration: Example 41. Fragment of Mendelssohn.]
Measures 1, 2, 3 and 8 constitute the original regular four-measure phrase.
The following regular phrase (to be found in the last movement of Beethoven's pianoforte sonata, op. 28):—
[Illustration: Example 42. Fragment of Beethoven.]
is immediately followed by this lengthy and elaborate extension:—