THE HAND-ITS MECHANISM, &C. 471 
covering, whether it be the nail, or crust, or hoof, we can hardly 
doubt; and an unexpected proof of this offers itself in the horse. 
There are some very rare instances of a horse having digital 
extremities. Accordino; to Suetonius, there was such an animal 
in the stables of Cassar ; another was in the possession of Leo 
X; and Geoffrey St. Hilaire, in addition to those, says, that he 
has seen a horse w ith three toes on the fore feet, and four on the 
hind foot. Such a horse was not long since exhibited in town, 
and at Newmarket. These instances of deviation in the natural 
structure of the bones were accompanied with a corresponding 
change in the coveriiis:: the toes had nails, not hoofs. 
We have thus far followed our author in his description of the 
horse’s foot. These latter examples of his are to shew that there 
is a relation between the internal configuration of the toes and 
their covering ; that when there are five toes complete in their 
bones, they are provided with perfect nails. When two toes 
represent the whole, as in the cleft of the ruminant, there are 
appropriate horny coverings; and that when the bones are joined 
to form the pastern bones and coffin bones, there is a hoof or 
crust, as in the horse, quagga, zebra, and ass. Speaking of 
the hoofs of animals, and of their sensibility, he says, “ the hu¬ 
man nail is a continuation of the cuticle, and the hoof of an ani¬ 
mal belongs to the same class of parts. In observing the manner 
in which the nerves enter the hoof, we have, in fact, a magnified 
view of that which exists, but is only more minute and delicate 
in the cuticular covering of the fingers. We may take the horse’s 
foot as the example. When the crust or hoof, which is insensi¬ 
ble, is separated from the living part, we see small villi hanging 
from the vascular surface, and which have been withdrawn from 
the crust: looking to the inside of the crust, we perceive the 
pores from which these villi have been pulled. These processes 
of the living surface are not merely extremities of nerves ; they 
consist of the nerves and the necessary accompaniment of mem¬ 
brane and bloodvessels on a very minute scale. For it must be 
remembered that nerves can perform no function unless supplied 
with blood, all qualities of life being supported through the 
circulating blood. These nerves, so prolonged into the hoof, 
receive the vibrations of that body. By this means the horse is 
sensible to the motion and pressure of its foot, or to its percussion 
against the ground; and without this provision,there would be a 
certain imperfection in the limb.” 
K. 
