A manual of dental anatomy, human and comparative / by Charles S. Tomes ; edited by H.W. Marett Tims and A. Hopewell-Smith.

  • Tomes, Charles S. (Charles Sissmore), Sir, 1846-1928.
Date:
1914
Catalogue details

Licence: In copyright

Credit: A manual of dental anatomy, human and comparative / by Charles S. Tomes ; edited by H.W. Marett Tims and A. Hopewell-Smith. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    lime, and though nothing is known of its development A transverse section of pinna shell shows the pattern produced by the approximation of the sharply defined rods, but it is not possible to make out the existence of a cementing substance. But if a section be rubbed down and then fastened to a glass slide and subsequently decalcified in situ, the rods wholly disappear, the pattern being, however, still maintained by the organic honeycomb in which they lay, and by which, presum- ably, their form was moulded. If a piece of human enamel be similarly treated, nothing is left upon the slide, so that it is certain that, whatever may have been the case during its formation, when it is finished the organic matrix is gone. And here again the resemblance fails in many respects, for it is probable that the organic mould is of a quite different nature ; indeed, as will presently be seen, no thoroughly distinct interstitial substance exists in enamel. The recent researches of Leon Williams (16) have thrown much light upon the structure of enamel, and illustrated as they are by very beautiful and untouched photomicrographs, must be accepted as, at all events, indisputable as respects that which can be seen, although exception might be taken to his statement that photography can show all that the human eye can see. In a sense this is true, though, as Professor Sir E. Schafer has said, it is with one's finger on the fine adjustment that, after all, the intimate structure of any tissue must be unravelled. Still photographs have the unquestionable value that, unlike a drawing, they cannot be strained to express the preconceived ideas of the observer; on the other hand, high- power photographs represent truly only one plane, and appearances due to other planes out of focus in the thickness of the section occur, to say nothing of diffraction errors which may mislead. He completely demonstrates that enamel is a solid tissue, that is to say, that the minute canals said by von Ebner to be present in it have no real existence, and that this observer is also mistaken in supposing that the striation is an artificial appearance induced by reagents. Leon Williams believes that the completed enamel rod is a regular beaded calcified column, the beadings of which are the cause of the appearance of striation, and that these beaded rods are embedded in a matrix which fills up all the interstices,