Elements of comparative zoology (1904) Elements of comparative zoology elementsofcompar1904king Year: 1904 B FIG. 111.—Relations of the olfactory organ. A, in fishes; B, in higher ver- tebrates, b, brain; i, internal nostril; n, external nostril. The sensory surface is folded. fish can perceive odors in the water only as it swirls in and out of the nasal sac. In the air-breathing forms, odors in the air are drawn with the breath over the sensory surface. The essential part of the ear, the inner ear (fig. 112), con- sists of a thin membranous sac on either side of the head. s In three places t
Elements of comparative zoology (1904) Elements of comparative zoology elementsofcompar1904king Year: 1904 B FIG. 111.—Relations of the olfactory organ. A, in fishes; B, in higher ver- tebrates, b, brain; i, internal nostril; n, external nostril. The sensory surface is folded. fish can perceive odors in the water only as it swirls in and out of the nasal sac. In the air-breathing forms, odors in the air are drawn with the breath over the sensory surface. The essential part of the ear, the inner ear (fig. 112), con- sists of a thin membranous sac on either side of the head. s In three places this sac is so pinched as to form small tubes (semicircular canals) open at either end into the main chamber. The whole is filled with fluid in which are nu- merous minute solid par- ticles (otoliths). At one FIG. 112.—Diagram of mammalian ear. c, , /. i •> •, cochlea; e, Eustachian tube; s, semicir-end 01 eacll tUD6 ana at cular canals, connected with the central -. ,-1 n-ro sac and separated from the surrounding places 111 [116 bone (black) by a space; t, tympanic i cavity closed externally by membrane, and SeilSOlT OrgailS Connected traversed by a bone, which conveys the ..-, -, -,•. sound-waves to the inner parts. With the auditory nerve. Sound-waves entering the ear set the fluid in motion, causing the otoliths to strike the sensory organs and thus to stimulate the nerve.
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