. Cassell's natural history . ia, tlo not float freely in the chest, butextend clown the spine, to which they are attached, and till up the hollows between theribs at their junction with the spine. They are firm in texture, and consist of distin-<iuishable cells, filling- not only the hollow bones with air, but also cavities and nieni-liraneous sacks, which are variously situated, but manifestly designed nioie completely toaerate the blood, and to increase the lightness of the body in the surrounding atmos-phere. And thus— • Tlic vital ail Pervades the swavining seas and licaving earths, AV
. Cassell's natural history . ia, tlo not float freely in the chest, butextend clown the spine, to which they are attached, and till up the hollows between theribs at their junction with the spine. They are firm in texture, and consist of distin-<iuishable cells, filling- not only the hollow bones with air, but also cavities and nieni-liraneous sacks, which are variously situated, but manifestly designed nioie completely toaerate the blood, and to increase the lightness of the body in the surrounding atmos-phere. And thus— • Tlic vital ail Pervades the swavining seas and licaving earths, AVhere teeming Nature broods licr myriad births ; Fills the tine lungs of all that breathe or bud, AVarms the new heart, and dyes the gushing blood; With lifes first s^Kirk ins])ires th organic frame, And as it wastes, renews the subtle flame. In glancing at the organs of respiration and voice, it may be observed tliat, in birds, thelipper aperture is at a considerable distance fronr the articidating parts. It is called the. no. 1«.- oHoANs OK hesiIkation and voice. iipiicr hiriiux, has its lips innnovcabie, and is not coveivd with un rpiff/nffix. At the bottom of the Iriiclirii (r), 111! point at whiili it branclii s into two, to form tin- hroiir/iin/ inhva (nn), UESriKVTIOX OF niKDS. 23 wliieh are represented entering the lungs (ll), and there is a piece of bone Ijing across,surmounted tli a crescent-shaped membrane (m) . On each side and below this piece ofbone—at the origin of each bronchial tulio—is an opening, the two lips of which are real,vocal chords. The first arch of the bronchial tubes is sej)arated by a membrane from thelast little bone which terminates the trachea. It is in this double drimi, called the lowerlarynx, that the voice of biids is formed, by means of the complicated play of the numerousmuscles which stretch or relax the vocal chords and the membranes of this wonderfulapjiaratus. It may be easily imderstood that the enormous volume of air, contai
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectbirds, bookyear1854
