File:Dental cosmos (1893) (14592458339).jpg

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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the development of the teeth ofthe Chamaeleonidae, nor of any other acrodont reptile. As the Chamse-leon possesses multituberculate molars in the posterior portion of its I I 12 THE DENTAL COSMOS. jaws, therefore the development of the teeth in this animal must bedoubly interesting, especially with regard to the origin of molarsgenerally. I examined the heads and jaws of both young and adult animals.Unfortunately, I was unable to procure embryos of the Chamaeleon.All the material was sectionized into series of 20 ft thickness, and doublystained with alum carmine and bleu de Lyons. The figures havebeen drawn with Oberhiiusers camera. Fig. 1 shows the teeth of the upper jaw five times magnified. Theanterior teeth are unituberculate, the posterior ones bi- or trituber-culate. All teeth are fused to the edge of the maxilla. There is noshedding of teeth in the Cham&leon, nor could I prove it to take placein Hatteria ; but still there is, especially in the upper jaw, behind the Fig. 1.
Text Appearing After Image:
Fig. 1.—Chamcrlcon vulgaris. Teeth of the upper jaw. Only the two anterior of the threeshells of the last molar are fused ; the posterior one is still isolated. 5 diam. functional teeth, a well-developed dental or reserve ridge. On itsposterior end there takes place, throughout life, a continuous new for-mation of teeth. Accordingly, older animals have always a largernumber of teeth than young ones. Although I examined macro-scopically, with a lens, a number of heads of the Chamaeleon, and mi-croscopically six different series of sectionized jaws, I never succeededin finding any indications of reserve teeth. The dental ridge showedindeed at its posterior end a slight depression (Fig. 2, ZL), but therewas in its neighborhood no accumulation of mesodermal cells, foundtypically in true germs of teeth For this reason, the slight thicken-ing of the end of the dental ridge in Fig. 2 cannot be regarded ascommencement of reserve teeth. The point of fusion of the teeth with the jaw-bones is

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