. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 263 buried in the membrane from which they rise, and the surface to which their basis is attached becomes the bottom of a closed sac: but this sac does not become inclosed in the substance of the jaw; so that teeth at diiferent stages of growth are brought away with the thick and S(jft gum, when it is stripped from the jaw-bone. The final fixa- tion of teeth, so formed, is effected by the develope- ment of ligamentous fibres in the submucovis tissue be- tween the jaw and the base of the tooth, whi
. On the anatomy of vertebrates. Vertebrates; Anatomy, Comparative; 1866. ANATOMY OF VERTEBRATES. 263 buried in the membrane from which they rise, and the surface to which their basis is attached becomes the bottom of a closed sac: but this sac does not become inclosed in the substance of the jaw; so that teeth at diiferent stages of growth are brought away with the thick and S(jft gum, when it is stripped from the jaw-bone. The final fixa- tion of teeth, so formed, is effected by the develope- ment of ligamentous fibres in the submucovis tissue be- tween the jaw and the base of the tooth, which fibres become the medium of con- nection between those parts, either as elastic ligaments or by continuous ossifica- tion. Here, therefore, is represented the ' follicular ' stage of the developement of a Mannnalian tooth : but the ' eruptive' stage takes place without pre- vious inclosure of the follicle and matrix in the substance of the jaw-bone. In BaUstes, Scarus, Sphyraiia, the Sparoids, and many other Fishes, the formation of tlie tcctli presents all the usual stages which have been observed to succeed each other in the dentition of the higher Vertebrates : the papilla sinks into a follicle, becomes surrounded by a capsule, and is then included within a closed alveolus of tlie growing jaw, figs. 259, 261, c, where the develope- ment of the tooth takes place and is followed by the usual eruptive stages. A distinct enamel-pulp is developed from the inner surface of the capsule in BaUstes, Scarus, Sarffus, and Chri/so- jihi'i/s. In the formidable Barrncada {Sj)Ii>/>-ana) the loss or fracture of the lancet-shaped teeth, in the conflict witli a struggling ]irey, is re|iaired by an uninterrupted succession of new puljis and toctli. The existence of these is indicated by tlie foramina, which are. Verticnl section of jaw and tuL'tb [Laii,. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colorat
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Keywords: ., bookauthorowenrichard18041892, bookcentury1800, bookdecade1860
