On the knowledge of the age of the horse by his teeth. With remarks / [Bracy Clark].

  • Bracy Clark
Date:
1826
Catalogue details

Licence: Public Domain Mark

Credit: On the knowledge of the age of the horse by his teeth. With remarks / [Bracy Clark]. Source: Wellcome Collection.

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    or six of these irregular figured tubes or cases placed together, being formed by as many pulps, first by points, and then united into one shell; these shells are quickly covered with enamel, laid on in three coats, as we have stated : first the striated, next the reticulated, and finally the glossy coat. The first, however, I consider rather as a foliated coat, being formed of pa- rallel leaves, somewhat like the inside of the horse’s hoof, to hold on the enamel more securely, and to afford, perhaps, a slight degree of elasticity and yielding: as an homogeneous, hard, chrystaline body like this, would be liable to be more easily fractured, without this softer bed to act against. Each of these may be seen distinctly by looking down the course of the tooth, from its crown to the shank, being formed in succession, and we ap- prehend have not been distinctly noticed before. These shells being strengthened by enamel without, and hard bone within, are in a state to receive a most extraordinary process for their union and consolidation into one mass, which is done, according to present know- ledge and apprehension, by the membranes of the capsule, which had just covered them with enamel, changing the nature of their secretion, and pour- ing forth solid bone between these cases, and filling up and obliterating all the intervening spaces, till the tooth becomes one solid body, and the mem- branes are excluded by their own secretions. For the accomplishment of this purpose, processes are sent off from the investing capsule, which wind among all the convolutions of the shells, and deposit this bony matter. Now, it has been said, that these membranes pass down perpendicularly from the capsule, going down between the shells, and pouring out their secretions, till the spaces are filled ; this view of it, however, would lead us into embarrassment, and give us an erroneous idea of the real process : for this matter is not poured out as lead might be sup- posed to be poured out, among some pipes or tubes stuck in a bed of sand, where the process of consolidation would commence at the bottom and pro- ceed upwards: since, if we examine the horse’s tooth, we see evidently enough, that the consolidating process begins at top, near the crown of the tooth, in order that this part should be early brought into use. Now, if these membranes dipped down perpendicularly from above, they would, by the filling up of the tooth at top, be cut off from their sources, and be de- stroyed, that it would appear necessary, in order to conceive this process aright, that we should consider these membranes, though standing perpen- dicularly, in respect to the position of the tubes or shells, to have rather a
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