Licence: Public Domain Mark
Credit: The works of John Hunter. 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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![whole surface, as the tooth grows, the first formed will be the thickest; and the neck of the tooth, which is the last-formed part inclosed in this capsule, must have the thinnest coat; and the fang, where the peri- osteum adheres, and leaves no vacant space, will have none of the enamel. At its first formation it is not very hard ; for by exposing a very young tooth to the air the enamel cracks and looks rough; but by the time that the teeth cut the gum, the enamel seems to be as hard as ever it is afterwards; so that the air seems to have no effect in hard- ening ita. Of the Manner of Shedding the Teeth. An opinion has commonly prevailed that the first set of teeth is pushed out by the second; this, however, is very far from being the case : and were it so, it would be attended with a very obvious incon- venience ; for, were a tooth pushed out by one underneath, that tooth must rise in proportion to the growth of the succeeding one, and stand in the same proportion above the rest. But this circumstance never happens, neither can it, for the succeeding teeth are formed in new and distinct sockets, and generally the incisores and the cuspidati of the second set are situated on the inside of the corresponding teeth of the first set * ; and we find that in proportion to the growth of the suc- ceeding teeth, the fangs of the first set decay, till the whole of the fang is so far destroyed that nothing remains but the neck, or that part of the fang to which the gum adheres f, and then the least force pushes the tooth out. It would be very natural to suppose that this was owing * PI. VI. f. 12, 13. t PI. VIII. f. 16, 17, & 18, which show the gradual decay in the single and double teeth, and also in one grinder of a horse. a [According to the most accurate observations which I have been able to make, and they are confirmed by those of others, the substance which Hunter terms “another pulpy substance,” adhering to the inside of the capsule, is nothing more than a thickened and turgid state of the inner layer of the capsule itself, surcharged with blood and probably also with the earthy matter which it is about to deposit, constituting the future enamel- covering of the crown of the tooth. This thickening appears to be somewhat analogous to that extraordinary turgescence which is observable in the mantle of certain species of snail, as our own Helix Pomatia immediately before the calcareous winter operculum is poured out from every part of its surface. The enamel when just deposited is not much more solid than thick cream. It soon sets, but is at first but little coherent, being easily pulverized; it gradually, however, assumes its crystalline form, becomes semitransparent, and extremely hard.]](https://iiif.wellcomecollection.org/image/b21996635_0002_0063.jp2/full/800%2C/0/default.jpg)
