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

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her development of the multituberculate molars could) bestudied exceedingly well in a young Chamaeleon nine cm. in length.By accident, the direction of our section was not exactly frontal, butslightly slanting. Therefore as the three cusps of the molars lie sagit-tally behind one another, it happened that two of them were in thesame section, and then could be seen plainly that the last molar ofthe lower jaw possessed three shells (or caps), still completely ON THE DEVELOPMENT OF THE TEETH IN THE CHAMELEON. III5 separated from one another, but in the upper jaw the dental shellswere already fused on their bases. Fig. 6 shows, to the left, the pos-terior end of the middle cusp ; to the right, the anterior end of theposterior cusp. Both are still comparatively widely separated fromeach other. The high columnar cells of the inner, or true, enamelepithelium, cover only the individual dental shells, and are not fusedwith each other, as is the case with the closer-standing papilla? of Fig. 4.
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Fig. 4.—Chanuzleon vulgaris, 22 cm. long. Frontal section through the (isolated) mediancusp of the penultimate molar of the lower jaw. DK, dentine germ ( pulpi ; D, dentine ; S,enamel; SP, enamel pulp ; SEi, inner enamel epithelium; SEa, outer enamel epithelium ; ZL,dental ridge; E, epithelium of the jaw; X, ingrowth of the dental ridge; O.d., Os dentale;O.c, Os coronoideum. 8odiam. the mammalian molars. Fig. 7 shows how, after fusion of the shellsalong their bases, the high covering enamel-cells become compressed. All three dental shells in Fig. 6 are invested by a common enamel-organ, with a strongly developed enamel-pulp and external epithe-lium. The end of the dental ridge is only slightly constricted offfrom that enamel-organ. As soon as the three shells fuse with oneanother, the enamel-pulp and outer epithelium commence to degener- 1116 THE DENTAL COSMOS. ate. But the inner enamel epithelium remains functional for sometime, until the formation of enamel has ceased. The enamel

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