In Ancient Greek music theory, the chromatic genus (Greek: χρωματικό γένος or χρωματική) (also known as chrōma, from the Greek word χρώμα, "colour") is a genus of the tetrachord characterized by an upper interval of a minor third. The two middle notes of the tetrachord were movable (kinoumenoi) while the two outer notes were immovable (hestōtes) (Mathiesen 2001, 6.iii.c). The movable members of the tetrachord (the pyknon) is divided into two adjacent semitones (hence this genus is the origin of the modern term, chromatic).
Note that the scale generated by the chromatic genus is not like the modern chromatic scale. The modern (18th century) well-tempered chromatic scale has 12 pitches to the octave, and consists of semitones of various sizes; the equal temperament common today, on the other hand, also has 12 pitches to the octave, but the semitones are all of the same size. In contrast, the ancient Greek chromatic scale had seven tones to the octave (assuming alternating conjunct and disjunct tetrachords), and had undivided minor thirds as well as semitones.
The (Dorian) scale generated from the chromatic genus is composed of two chromatic tetrachords:
Whereas in modern music theory, a chromatic scale is:
- D D♯ E F F♯ G G♯ A A♯ B C C♯ D D♯ E ...
Read more about Chromatic Genus: Tunings of The Chromatic, Byzantine Music
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—Henry David Thoreau (1817–1862)