as it is their vibration which causes the sound of the voice.

Above the lower ligaments of the glottis are situated the ventricles of the larynx, the cavity of which is considerably more spacious than it at first appears. The outer, under, and upper sides of this cavity are formed by the muscle that constitutes the vocal chords, turned upon itself. The extremity, or front side of the cavity, is formed by the thyroid cartilage. By means of these ventricles, the lips of the glottis are perfectly insulated at their upper edge.

If we examine above the opening of the ventricles, we shall find two bodies which have a great analogy in their arrangement to the vocal chords, and form a second glottis above the first. This apparatus is formed by the upper edge of the vocal chords, a little fatty cellular tissue, and the common lining of the larynx, which covers them before entering into the ventricles.

THE WINDPIPE AND ITS BRANCHES.

The tube which conveys the air to the lungs may be considered as a regular continuation of the larynx, being composed of gristly rings, united by a muscular coat which sheathes the whole, and lined by the same mucous membrane, which is continued from the mouth. There is, subjacent to

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this, a nervous layer or coat which renders it very sensible, though the cartilaginous rings, while in a state of health, are almost destitute of feeling, (no nerves being traceable into their substance,) and for that reason do not readily inflame, nor suffer irritation. It may be remarked that the gristle which composes the rings of the windpipe is fibrous rather than hard and brittle, and it will consequently bend, without breaking, in any direction. They are also elastic along with this property of suppleness, and recover their position when forcibly distended or contracted. Distinct from this property, though analogous to it, is the extensibility and contractibility of the rings from causes acting slowly, such as the pressure of a tumour or of a tight neckcloth. This property is of great importance to be recollected in the management of the voice, with regard to its improvement or preservation.

When the windpipe enters the chest, it divides itself into two branches, one going to the right lung and the other to the left. These branches are again subdivided into a great many twigs, which become gradually smaller, and lose their gristly and ringed structure as they dip deeper into the substance of the lungs, till at last their extreme divisions terminate in the small cells which form the chief part of the substance of the lungs, and alternately receive and emit the air we breathe: the shape and magnitude of the cells are va

rious, but they are all united by the common yet delicate mucous web, which is the general connecting chain of the whole body. Keil calculated that the number of these air-cells in one of the lungs of a healthy man was 1,744,000,000: this is, in all probability, greatly exaggerated, but we know that in a healthy individual the lungs will contain during a strong inspiration about 120 cubic inches of air.

2. THE MOUTH AND THE PARTS

ADJACENT.

Authors who have treated of the organs of the voice have paid too little attention to the parts above the vocal chords, which the sound traverses after it is produced; but as these exert an important influence on the character of the sound in clearness and intensity, it becomes, we think, indispensable to examine their structure. The first of these in order of situation are,

THE TUBES OF THE EARS.

A little above the valve of the orifice of the windpipe, on each side of the root of the tongue, is a small opening leading to a tube which communicates with the ear, and is supposed, so far as the ear is concerned, to serve a similar purpose to the air-holes of a violin or of a drum. With regard to the voice, these tubes appear to perform a very distinct part in rendering the sound clear and free;

for the instant that the tubes are obstructed or closed by accident or disease, the sound of the voice appears dull and muffled. The utility of the tubes to the clearness of the voice is farther demonstrated, from the circumstance that the orifice of the tubes is always opened as a consequence of opening the mouth,-Providence having evidently constructed them in this manner for the aid of speech. The ear, indeed, being formed of very hard bone, and containing the sonorous membrane of the drum, the sound of the voice entering it through the air-tubes must necessarily be increased by its passage along what we may perhaps be allowed to call the whispering galleries of the ears. It is necessary to mention that these air-tubes are lined by the same mucous membrane which lines the nose, the mouth, and the windpipe, and of course are equally liable to be affected with colds, and obstructed, like the nostrils, by swelling and inflammation, or by an increased discharge of

mucus.

THE NASAL PASSAGES.

The effects produced on the voice by different states of the nasal passages is a matter of common observation; but in order to understand the matter thoroughly, it will be requisite to describe these. The nose is a double channel for the passage of the

air in breathing, the opening of which is always free. This circumstance, as Bichat remarks, distinguishes it from all the other external openings in the body, and is of much importance in breathing as well as in speaking; for it is thus prevented from accidental obstructions, arising from palsy or other diseases. In hysteric fits, and other convulsions, accordingly, when the windpipe is partially constricted, the nostril remains open to admit the air as soon as the constriction is removed. The nostril remains open also in the dreadful affection of locked-jaw-when the teeth will not admit the blade of a knife between them.

The more external part of the nostrils is larger, longer, and less winding and oblique, than they become farther inwards. The middle part, which begins about an inch from the outer orifice, is much narrower, but of greater extent from the roof to the floor of the nostril. It is indeed so narrow, that the least swelling here obstructs the air in breathing, as in the case of colds. The innermost part of the nostrils is united into one channel, which opens into the back part of the mouth, immediately over the opening of the larynx. It is more narrow and oblique, and much shorter, than the two former portions above described.

The middle and the innermost parts of the nostrils open into several hollows or cells in the