. The biology of the frog. Frogs. THE BIOLOGY OF THE FROG but of small size and uniform structure. With the excep- tion of the two patches of vomerine teeth, they are confined to the upper jaw. The jaw teeth rest against the dental processes of the maxillary and premaxillary bones, to which they are attached by cement substance. They are embedded in the mucous membrane of the mouth, beyond which they project only for a short distance. Each tooth is approximately cy- lindrical in form, tapering slightly toward the upper end, which is somewhat incurved. The basal portion of the tooth whic
. The biology of the frog. Frogs. THE BIOLOGY OF THE FROG but of small size and uniform structure. With the excep- tion of the two patches of vomerine teeth, they are confined to the upper jaw. The jaw teeth rest against the dental processes of the maxillary and premaxillary bones, to which they are attached by cement substance. They are embedded in the mucous membrane of the mouth, beyond which they project only for a short distance. Each tooth is approximately cy- lindrical in form, tapering slightly toward the upper end, which is somewhat incurved. The basal portion of the tooth which is fas- tened to the jaw is called the root. Upon this rests the crown, which is separated from the root by a transverse furrow. In the center is a cavity filled with the pulp, which is a very vascular tissue in which the cells (odontoblasts) are situated that produce new material for the growth of the tooth, face; B, lateral The greater portion of the crown is com- posed of substance called dentine which forms a hard calcareous wall, traversed by PulP numerous fine branching canals which lead from the pulp cavity. The upper half of the crown is coated with a very hard, resistent layer of enamel which is considerably thickened over the tip. The enamel shows a stratified structure, but it does not contain the verti- cal prisms found in higher forms. Outside of the enamel there is a thin, resistent membrane, the cuticula dentis. The root of the tooth is composed of a substance resembling bone. The teeth of the frog are not used for mastication, but only for holding prey, which is the primitive function of teeth among vertebrate animals. There is a continual replace- FlG. 9. — Teeth of the bull frog. A, view of inner face; B, lateral face ; c, crown ; r, root; /, sec- tion of lower jaw; pt 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
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Keywords: ., bookauthorholmessamueljsamuelja, bookcentury1900, bookdecade1910
