. Comparative zoology, structural and systematic. For use in schools and colleges. Zoology. DEVELOPMENT. 205 velopiiient of the common Cral), so different is the out- ward form of the newly hatclied embryo from that of the adult, that the former has been described as a distinct species. The most remarkable example of metamorphosis among Vertebrates is furnished by the xlmphibians. A Tadpole —the larva of the Frog—has a tail, but no legs; gills, in- stead of lungs; a heart precisely like that of the Fish; a horny beak for eating vegetable food, and a spiral intes-. Fig. 173—MetmioiphoMS of the
. Comparative zoology, structural and systematic. For use in schools and colleges. Zoology. DEVELOPMENT. 205 velopiiient of the common Cral), so different is the out- ward form of the newly hatclied embryo from that of the adult, that the former has been described as a distinct species. The most remarkable example of metamorphosis among Vertebrates is furnished by the xlmphibians. A Tadpole —the larva of the Frog—has a tail, but no legs; gills, in- stead of lungs; a heart precisely like that of the Fish; a horny beak for eating vegetable food, and a spiral intes-. Fig. 173—MetmioiphoMS of the Newt. tine to digest it. As it matures, the hinder legs show themselves, then the front pair; the beak falls off; the tail and gills waste away; lungs are created; the digest- ive apparatus is changed to suit an animal diet; the heart is altered to the Eeptilian type by the addition of another auricle; in fact, skin, muscles, nerves, bones, and bloodv vessels vanish, being absorbed atom by atom, and a new set is substituted. 31'oultinrj, or tlie periodical renewal of epidermal parts, as the shell of the Lobster, tlie skin of the Toad, the scales of Snakes, the feathers of Birds, and. 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 Orton, James, 1830-1877. New York, Harper and brothers
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Keywords: ., bookcentury1800, bookdecade1880, bookpublishe, booksubjectzoology
