With regard to the difference of form which we have just pointed out, we have sometimes heard the following comparison made: the contour of the hoofs of the fore-limbs, viewed from below, recalls that of an apple; that of the hoofs of the hind-limbs recalls the outline of a pear.
As a mnemonic this comparison is insufficient, for nothing connects either of the forms indicated with the region to which the hoofs belong.
We much prefer one made for us this very year by one of the students of our course at the School of Fine Arts, after the lecture in which we had just pointed out the differences in question. Giving the idea of a semicircle and an ogive, which we described above, he remarked to us that the idea would perhaps be more easily fixed in the memory if we associated with it the idea of the chronological order in which the Roman and ogival art succeeded. Indeed, as the Roman art preceded the ogival art, so the hoofs which have the semicircular form precede those which have the form of an ogive.
This interpretation appeared to us ingenious; this is why we wished to give it here a place which seems to us to be merited.
Fig. 104.—Left Posterior Foot of a Horse: External Aspect.
The wall of the hoof of a fore-limb, viewed on one of its lateral surfaces (see [Fig. 98]), is more oblique than that of one of the hind-hoofs looked at in the same way ([Fig. 104]). This difference, very marked especially at the region of the toe, is correlated with that of the direction of the pastern. In fact, in the anterior limbs this is a little more oblique than in the opposite ones.
We have still to describe, in connection with the horse, some epidermic tissues, which are known as chestnuts.
The chestnut is a small, horny plate which is found on the internal surface of each of the limbs, at a level differing on the anterior from that of the posterior ones.