The passing major seventh and its root may appear on the weak beat, even when approached in similar motion as in Fig. 37_a_.  The seventh must then be treated as a passing-tone.

[Illustration:  Fig. 37.]

The cadences in Fig. 38 are good when writing second species in both parts. 
Those having the second species in one part only, may also be used.

[Illustration:  Fig. 38.]

Writing the second species in both parts will, in this lesson, be confined to a mixture of the first and second species, as in Fig. 39.

In this do not use the second species more than four measures continuously in one part.  It will be noticed that the second species may occasionally be used in both parts.  In later lessons opportunity will be given to write it continuously in both parts.

[Illustration:  Fig. 39.]

EXERCISES

Write two eight-measure phrases mixing the first and second species. [Fig. 39.]

To cantus firmus a write one counterpoint above and one below, three notes to the measure. [Fig. 31.]

To cantus firmus b write one above and one below, in the second species.

CANTI FIRMI

[Illustration:  Fig. 40.]

LESSON IV

THIRD SPECIES

[Illustration:  Fig. 41.]

In this species, four notes are written in the counterpoint to each note of the cantus firmus.  The counterpoint may begin on the first, second, or fourth quarter.  The second quarter is, however, the most usual. [Fig. 42.]

[Illustration:  Fig. 42.]

The exercises should begin and end with tonic harmony.

When the counterpoint begins on the first quarter it must form a perfect consonance with the cantus firmus.  When on the second or fourth quarter, any consonance may be used.

All previous rules are to be regarded, unless exceptions are made.

At least one of the first three quarter-notes of a measure should be left degreewise. [Fig. 43.]

[Illustration:  Fig. 43.]

The last quarter of a measure is usually left degreewise.  If approached by a skip or by a degreewise progression of at least two quarter-notes, it may be left by a skip in the opposite direction from which it was approached.  A skip of a third in the same direction is also good when this skip is preceded by a skip of a third (d). [Fig. 44.]

[Illustration:  Fig. 44.]

Parts may cross occasionally.

The use of non-harmonic tones, as in Fig. 45, is good in either part.  At a the passing-tone, instead of progressing directly to the adjacent chord-tone, skips a third to the other side of it and then returns.  The embellishment is treated in the same way, but is most effective when the principal tone is the leading-tone, as at b.  In both cases the counterpoint should continue degreewise through the chord-tone. [Fig. 45.]