en by carbonic acid
exhaled from the lungs of the assembly, so that the purification of the
blood must necessarily become more and more imperfect.

"Besides their principal function of purifying the blood," writes Sir
Morell Mackenzie, "the lungs are the bellows of the vocal instrument.
They propel a current of air up the windpipe to the narrow chink of the
larynx, which throws the membranous edges or lips (vocal cords) of that
organ into vibration, and thereby produces sound. Through this small
chink, the air escaping from the lungs is forced out gradually in a
thin stream, which is compressed, so to speak, between the edges of the
cords that form the opening, technically called the glottis, through
which it passes. The arrangement is typical of the economical
workmanship of nature. The widest possible entrance is prepared for the
air which is taken into the lungs, as the freest ventilation of their
whole mucous surface is necessary. When the air has been fully utilized
for that purpose it is, if need be, put to a new use on its way out for
the production of voice, and in that case it is carefully husbanded and
allowed to escape in severely regulated measure, every particle of it
being made to render its exact equivalent in force to work the vocal
mill-wheel." Thus again is illustrated the close analogy between vocal
art and physical law, and further evidence given of the value of a
physiological method of voice-production as opposed to those methods
that are purely empirical. In fact when it is considered that speech is
Nature's method of communication and that song is speech vitalized by
musical tone, it would seem as if song were Nature's art and, therefore,
more than any other based on Nature's laws.

No effort is involved in holding the breath. The pause before emission
is accomplished without any internal muscular struggle, and without any
constriction of the larynx. Some writers lay down the rule that after
inhaling, the singer should retain the breath by closing the vocal
cords. The only objection to laying down this rule is that it is apt to
make the pupil perform consciously an act that is so nearly voluntary as
to be unconscious. It inclines the pupil to make an effort when effort
is unnecessary. Retain the breath and you can feel the vocal cords close
in consequence, and as if of their own accord, and open again with the
act of emission. It is all voluntary, or nearly so. In fact, artistic
breathing become