. Elements of zoölogy. Zoology. OYSTERS, ETC. 53 two parts, either double or single, and the orifices are surrounded by tentacles. Circulation.—The blood is purified (aerated) and food obtained by the same action. Water is drawn into the siphon opening farthest from the valve (Fig. 56, in), and, wafted along by the cilia, is thus brought in contact with the gills. The food-particles in the water are carried along to the toothless mouth (Fig. 55, o)y that, guarded by two pairs of sense organs (palpi), is placed at the end of the shell opposite the siphon. They then pass into the stom- ach and i
. Elements of zoölogy. Zoology. OYSTERS, ETC. 53 two parts, either double or single, and the orifices are surrounded by tentacles. Circulation.—The blood is purified (aerated) and food obtained by the same action. Water is drawn into the siphon opening farthest from the valve (Fig. 56, in), and, wafted along by the cilia, is thus brought in contact with the gills. The food-particles in the water are carried along to the toothless mouth (Fig. 55, o)y that, guarded by two pairs of sense organs (palpi), is placed at the end of the shell opposite the siphon. They then pass into the stom- ach and intestine that winds about and passing through. Fig. 56.—Bivalve with siphon, showing the foot. /, ligament; F, foot; m, mantle ; s, siphon ; ex., excurrent orifice ; in., incurrent orifice. Except the siphon and the large foot, the arrangement of organs is similar to that of the oyster. the heart finally connects with the siphon nearest the valve (Fig. 56, ex.), out of which all rejectementa passes. Extend- ing through the body is a glass-like rod, that is possibly a brace or support. The heart lies near the hinge (Fig. 55, k), and is composed of one ventricle and one auricle in the oyster. In other species the heart is three-chambered, or there may be two hearts of two chambers each. Arte- ries lead from the ventricle over the body, and veins carry blood to the gills g, where it is purified by the air in the water—then passing back to the auricle. The nervous system consists of three pairs of ganglia—cerebral, pedal, and a pair that send nerves to the internal organs, gills,. 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
