Dental cosmos (1893) (14775984081)

Identifier: dentalcosmos3518whit (find matches)

Title: Dental cosmos

Year: 1893 (1890s)

Authors: White, J. D McQuillen, J. H. (John Hugh), 1826-1879 Ziegler, George Jacob, b. 1821 White, James William, 1826-1891 Kirk, Edward C. (Edward Cameron), 1856-1933 Anthony, Lovick Pierce, 1877-

Subjects: Dentistry

Publisher: Philadelphia : S. S. White Dental Manufacturing Co

Contributing Library: The College of Physicians of Philadelphia Historical Medical Library

Digitizing Sponsor: The College of Physicians of Philadelphia and the National Endowment for the Humanities

Text Appearing Before Image:

um of the jawdirectly. All the teeth of this dental plate are fused on their basesby means of a cement socle. If we imagine that in the thus closelyplaced developing teeth of the dental plates of Spelerpes the enamelepithelium of several neighboring teeth fused and persisted thus forsome time, then the teeth would coalesce with their dentine, and notonly with their cement socles. The result would be compound teeth, 11 iS THE DENTAL COSMOS. and such really occur among fishes and Dipnoi, although rarely.Why should similar phenomena not be recapitulated among thehigher vertebrates ? In fact, we noticed above that the trituberculate molars of the Cha-maeleon arise ontogenetically, three typical enameled teeth becomingfused, sagitally from before backward. The three teeth are not ofequal size, but the median one is higher and forms the protocone.If in the Chamaeleon the epithelial sheath should grow further, so thatthecodont teeth are formed, instead of the fusion of the teeth with Fig. 7.

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Fig. 7.—Chamczleon vulgaris, 9 cm. long. Section through the middle and hinder cusp ofthe last molar of the upper jaw. DK, dentine germ ; SP, enamel pulp; SEa, outer enamelepithelium; SEj, inner enamel epithelium ; ZL, dental ridge; LF, labial furrow; Gl.l., labialgland ; M, muscle; O.m., Os maxillare. 80 diam. the jaw-bones taking place, then the posterior molars would, in formand size, greatly resemble the molars of the Mesozoic Dromatherium. The theory of coalescence has found, so far, its greatest adversariesapparently among the paleontologists. Osborn reproaches me forhaving taken no notice of the Jurassic and Triassic mammals ; butperhaps he is not quite justified in doing so. On the contrary, thestudy of the Mesozoic mammals has confirmed me in my views. Ifan unprejudiced person sees a molar of the Triconodon, he would cer-tainly rather believe that in it three teeth are fused together thanembrace the theory of transformation. Dentists are familiar with the fact that even now

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1893

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