century only gives twenty-two matras for the octave, i.e. twenty-two srutis. The sruti is really a kind of half-way house to the semitone. More than two srutis are not usually sung in succession, though there are of course people who will sing the whole twenty-two of them in succession. Still that is acoustics and not music. So also the tetrachord might theoretically consist of as many notes as there are srutis within the fourth, but practically it is difficult to sing or play more than four notes.
The Saman chant is the earliest example of the Indian tetrachord which has remained until our time. In this the tetrachord is conceived of as a downward series of notes from the highest. Most of the early Indian modes, called Murchhanas, were also conceived as extending downwards. The Greeks too thought of the tetrachord in the same way.
The Saman chant pivoted on two notes called the udatta — 'raised' — the higher one, and the anudatta — 'not raised', the lower one. In course of time the interval between these was established as a fourth. Then, later, the notes of this tetrachord received distinct names. The highest was prathama — 'first' — then dvitiya, tritiya, chaturtha, down the scale. These names are found first in the Rikpratisakhya (c. 400 B.C.). Later, a note called svarita is also mentioned, and this seems to be a graced udatta, thus indicating a note higher than the prathama. Later still we find this note definitely established and called krnshta — 'high' {Taittiriya-pratisakhya c. A.D. 400). About the same time two other notes lower than the chaturtha appear. These are called mandra — 'low', and atisvarya — 'extremity'. This last was an extra note and was usually sung only in the cadence of the Saman chant. So we find the whole series of the seven notes, or svaras as they were called, of the octave.
We must, however, remember that there is a South Indian tradition that the raga Abhogi (S R g M D) represents the ancient Saman chant. This is pentatonic, and there can be little doubt that the Saman scale was pentatonic before it became heptatonic. We find that
