Ivan the Terrible, Act II 19 (cf. [Ex. 212]).
Division of parts can be adopted when one of them is entrusted with a melody, the remainder forming a sufficiently full accompaniment. The choice of parts to be divided depends upon the range of the upper one. When a harmonic-melodic phrase is repeated in different keys and registers, it may be necessary to distribute the parts and divide them in another manner, so as to maintain proper choral balance. As an illustration I give two extracts of identical musical context, the second (F major) being a third higher than the first (D major). In the first example the altos are added to the sopranos to strengthen the melody; the tenors and basses divisi form the harmony. In the second example the melody being a third higher may be given to the sopranos alone; the altos therefore take part in the harmony, and consequently the lower parts are divided in a different way.
Examples:
Sadko 173 and 177 (cf. [Ex. 205] and [206]); compare also the same music in G major 189.
[No. 309]-[310]. Ivan the Terrible, Act I 77.
[Example 307] is an instance of widely-spaced four-part writing forming the harmonic basis, with the melodic idea in the orchestra. In [Example 308], the same in musical context, the melodic figure is given to the sopranos, and among the other parts which form the harmony the tenors are divided.
Example:
[No. 308.] Sadko 152.
In polyphonic writing exceeding 4 part harmony the voices should be divided so as to obtain the necessary number of actual parts. One part may be divided into as many as three different parts, 3 sopranos, 3 altos etc.
Examples: