The exterior of the horse . rior extremity for the reception of the central enamel, it is everywherecovered by the enamel. It forms the parietes of the pulp-cavity and surroundsthe point of the central enamel, at first projecting into its interior. Primitively not abundant, it does not delay to fill the cavity which it con-tains in its interior by the addition of new layers which are deposited on thesurface of the old ones. This leads to a progressive atrophy of the pulp, whichextends gradually from the crown to the root. The more recent layers have a deeper coloration ; the tint of the oblite
The exterior of the horse . rior extremity for the reception of the central enamel, it is everywherecovered by the enamel. It forms the parietes of the pulp-cavity and surroundsthe point of the central enamel, at first projecting into its interior. Primitively not abundant, it does not delay to fill the cavity which it con-tains in its interior by the addition of new layers which are deposited on thesurface of the old ones. This leads to a progressive atrophy of the pulp, whichextends gradually from the crown to the root. The more recent layers have a deeper coloration ; the tint of the obliteratedparts also allows, in transverse and longitudinal sections, the recognition of theoutlines of the internal cavity at the beginning. This cavity is obliterated atfirst behind the central enamel, the distance which separates the latter from theposterior face being less considerable than that which separates it from the an-terior. Then the obliteration takes place in front. It is these layers of this new THE INCISORS. 613. 614 THE EXTERIOR OF THE HORSE. formation which, appearing npon the table at a given period in the form of atransverse yellowish band in front of and behind the central enamel, constitutewhat is called the dental star. To speak accurately, there are two of these dental stars, but the posterior,^always less distinct, most frequently passes unperceived. Nevertheless, in cer-tain teeth it is seen quite plainly. Fig. 286 represents the median longitudinal sections of pincers from horsesof different ages, which show the gradual diminution of the internal dentalcavity. It will be seen, too, in the very old teeth, that the extremity of the rootis covered by an abundant formation of radical cement directly applied uponthe surface of the ivory, from the fact of the disappearance of the enamel. Onthat account these teeth, Avhen the wear has reached this level, never display thewhiteness which they did primitively. The dentine is a substance less hard than the enamel,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecthorses, bookyear1892
