ly astonishing to those who study it by the aid of the
microscope. The figure annexed shows a small portion of this
extraordinary structure. It is from Koelliker's well-known work on
Microscopic Anatomy.

[Illustration]

Enough has been said to show that the ear is as carefully adjusted to
respond to the blended impressions of sound as the eye to receive the
mingled rays of light; and that as the telescope presupposes the lens
and the retina, so the organ presupposes the resonant membranes, the
labyrinthine chambers, and the delicately suspended or exquisitely
spread-out nervous filaments of that other organ, whose builder is the
Architect of the universe and the Master of all its harmonies.

Not less an object of wonder is that curious piece of mechanism, the
most perfect, within its limited range of powers, of all musical
instruments, the _organ_ of the human voice. It is the highest triumph
of our artificial contrivances to reach a tone like that of a singer,
and among a hundred organ-stops none excites such admiration as the _vox
humana_; a brief account of the vocal organ will not, therefore, be out
of place. The principles of the action of the larynx are easily
illustrated by reference to the simpler musical instruments. In a flute
or flageolet the musical sound is produced by the vibration of a column
of air contained in its interior. In a clarionet or a bassoon another
source of sound is added in the form of a thin slip of wood contained in
the mouth-piece, and called the _reed_, the vibrations of which give a
superadded nasal thrill to the resonance of the column of air.

The human organ of voice is like the clarionet and the bassoon. The
windpipe is the tube containing the column of air. The larynx is the
mouth-piece containing the reed. But the reed is double, consisting of
two very thin membranous edges, which are made tense or relaxed, and
have the interval between them through which the air rushes narrowed or
widened by the instinctive, automatic action of a set of little muscles.
The vibration of these membranous edges (_chordae vocales_) produces a
musical sound, just as the vibration of the edge of a finger-bowl
produces one when a wet finger is passed round it. The cavities of the
nostrils, and their side-chambers, with their light, elastic
sounding-boards of thin bone, are essential to the richness of the tone,
as all singers find out when those passages are obstructed by a cold in
the head.

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