CANTUS FIRMUS

[Illustration: Fig. 54.]




LESSON V

THIRD SPECIES IN BOTH PARTS


[Illustration: Fig. 55.]

The suggestions given for writing second species in both parts apply here,
except that when both parts move degreewise, any interval may come on the
second and fourth quarters, preferably a consonance. The third quarter is
treated the same as the second half when writing the second species in both
parts.

The augmented fourth, and diminished fifth and seventh, may be approached
in similar motion. [Fig. 56.]

[Illustration: Fig. 56.]

The augmented fourth following the perfect fourth, as in Fig. 56_a_, is good.

The minor seventh, and the major and minor ninth of a chord, may be used