. Animal and vegetable physiology considered with reference to natural theology. Natural theology; Physiology; Plant physiology; Biology. CIRCULATION IN FISHES. 245. tlie central organs are seen to consist of four cavities (c, d, e, f), opening successively the one into 356^ the other. The heart belongs exclusively to the gills; and there proceeds from it, not the aorta, but the trunk of those branchial arteries (f), which convey the whole of the blood to the respiratory organs (g, h). This blood, after being there aerated, is collected by the branchial veins (i,) which unite into a single tru
. Animal and vegetable physiology considered with reference to natural theology. Natural theology; Physiology; Plant physiology; Biology. CIRCULATION IN FISHES. 245. tlie central organs are seen to consist of four cavities (c, d, e, f), opening successively the one into 356^ the other. The heart belongs exclusively to the gills; and there proceeds from it, not the aorta, but the trunk of those branchial arteries (f), which convey the whole of the blood to the respiratory organs (g, h). This blood, after being there aerated, is collected by the branchial veins (i,) which unite into a single trunk (a), passing down the back, and performing, without any intermediate heart, the office of an aorta; that is, it divides into innumerable branches, and distributes the blood to every part of the system.* The blood is then reconveyed to the heart by the ordinary veins, which form a large vena cava (c). This vein is generally considerably dilated at its termination, or just before it opens into the auricle; constituting what has been termed a venous sinus. This, then, is followed by the auricle (d) and the ventricle (e); but, besides these cavities, there is also a fourth (f)» formed by a dilatation of the beginning of the branchial artery, and termed the hulbus arteriosus; contributing, doubtless, to augment the impetus * The caudal branch of the aorta is protected by the roots of the inferior spinous processes, joining to form arches througli which it passes; and frequently the artery is contained in a bony channel, formed by the bodies of the vertebrae, which eftcctually secures it from all external pressure. In the Sturgeon even the abdominal aorta is thus protected ; being entirely concealed within this bony 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 Roget, Peter Mark, 1779-1869. London :
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