. Elements of zoölogy. Zoology. BIRDS. 229. that sends it through the great aorta in- to numerous branches that lead all over the body. Respiration. —The breath- ing organs are shown in Fig. 269, /,/. The lungs, /, /, are two in number, spongy in con- sistency, and are attached to the walls of the cavity in which they are placed. The large air-passages of the lungs end in air-sacs, that in turn connect with the cavities of the bones, so that air taken in passes down the trachea, /, enters the lungs, /, /, aerating the blood there, also passing into the air-sacs and penetrating the hol- low bon
. Elements of zoölogy. Zoology. BIRDS. 229. that sends it through the great aorta in- to numerous branches that lead all over the body. Respiration. —The breath- ing organs are shown in Fig. 269, /,/. The lungs, /, /, are two in number, spongy in con- sistency, and are attached to the walls of the cavity in which they are placed. The large air-passages of the lungs end in air-sacs, that in turn connect with the cavities of the bones, so that air taken in passes down the trachea, /, enters the lungs, /, /, aerating the blood there, also passing into the air-sacs and penetrating the hol- low bones in every part of the body; thus the bird can alter its specific gravity at will. The air-sacs are nine in number ; two are placed in the abdomen, four in the thorax, and three near the wish-bone. Nervous System. — The brain (Fig. 270, 1) is larger than in the reptiles, and has no convolutions. Covering.—The birds differ from all other animals in being covered with feathers (Fig. 271), that are modified Fig. 269.—Parts of a bird. 1, digestive apparatus ; c, crop ; g, gizzard ; t, trachea ; b, d, bronchial tubes ; /, /, lungs ; 2, bones of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holder, Charles Frederick, 1851-1915; Holder, Joseph Bassett, 1824-1888, joint author. New York : D. Appleton and company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
