A manual of dental anatomy : human and comparative / by Charles S. Tomes.

Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: A manual of dental anatomy : human and comparative / by Charles S. Tomes. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    horny cones, stfinding upon a dermal papilla, and arising from a horn-producing groove around the base of the papilla (Beard, Morphological Studies, Jena, 1889). But the horny tooth of Myxine (the Hag) is yet more remarkable : in it the horny cone is superimposed, not upon a simple papilla, but upon a tooth germ which goes on to a. considerable degree of calcification. LilvC the horny cone of the larapi'ey, its free edges rest in a horn-forming groove of oral epithelium. Inside it is a hard cone which ajjpears to be a form of im- perfect dentine (with vascular canals in it 1): this Prof. Beard believes to be capped with enamel in one of his specimens, and in the interior of this is a pulp with odontoblasts. There is great difficulty in making out the structure, as these combined horny and calcified teeth almost defy ordinary methods of preparation. The figure given above is somewhat diagrammatic, and is compounded from Dr. Beard's figures, and from a section which he was so kind as to lend me. Between the liorny cap and the dentine is an epithelial structure which is in the position of, and seems to play the part of, an enamel organ. Calcified teeth are composed of one or more structures which arc in great measure peculiar to the teeth (although what is to all intents and purposes dentine, is to be found in the skeletons and in the dermal appendages of some fish, and other exceptions might be found to the absolute accu- racy of the statement), and hence are called dental tissues. Notwithstanding the existence of certain transitional forms it is not possible to doubt the propriety of a general division of dental tissues into three, viz., Dentine, Enamel, and C-emcntum. The first named of these constitutes the greater part of all teeth, and so fiir predominates in mass over the otiier constituents that, in very many cases, the tooth would
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