. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 38 COMPARATIVE ZOOLOGY. True bone is found only in Vertebrates, or back-boned animals. (5) Dental Tissue.—Like bone, a tooth is a combination of earthy and animal matter. It may be called petrified skin. In the higher animals, it consists of three parts: dentine, forming the body of the tooth, and always pres- ent ; enamel, capping the crown; and cement, covering the fangs (Fig. 31). The last is true bone, or osseous Fig. 9.—Highly magnified secti
. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. 38 COMPARATIVE ZOOLOGY. True bone is found only in Vertebrates, or back-boned animals. (5) Dental Tissue.—Like bone, a tooth is a combination of earthy and animal matter. It may be called petrified skin. In the higher animals, it consists of three parts: dentine, forming the body of the tooth, and always pres- ent ; enamel, capping the crown; and cement, covering the fangs (Fig. 31). The last is true bone, or osseous Fig. 9.—Highly magnified section of Dentine and Cement, from the fang of a Human Molar: a, b, marks of the original dentinal pulp; dentinal tubes, terminating in the very sensitive, modified layer, g; h, cement. Dentine resembles bone, but differs in having neither la- cunae nor (save in Shark's teeth) canaliculi. It shows, in place of the former, innumerable parallel tubes, reaching from the outside to the pulp-cavity within. The " ivory " of Elephants consists of dentine. Enamel is the hardest substance in the body, and is composed of minute six-sided. 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; Birge, E. A. (Edward Asahel), 1851-1950. New York : Harper & Bros.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1883
