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subject to a disease of the foot, from which the powerful draught and Flanders horses are exempt. The heavy horse, with less blood than the race horse, lifts its foot in a circle, and comes forcibly on the ground: whilst the horse for the turf, being light, moves with the foot close to the ground; no time is lost in lifting it high in the semicircle; the consequence of which is, that from the foot coming thus gently down, it wants the full play of the apparatus. Hence it may be understood how the lighter horse is subject to contractions of the foot; the bones, ligaments, and crust being out of use, the sole becomes firm as a board, the sides of the crust are permanently contracted, the parts have no longer their elastic play, and the foot striking on hard pavement suffers a shock or concussion; then comes a fever of the foot," which is inflammation, and that may go on to the total destruction of the fine apparatus. The proof of all this is, that unless the inflammation has advanced too far, by paring and softening the exterior of the hoof, so as to restore its elasticity, the veterinary surgeon may cure this contracted foot.
That a relation should exist between the internal structure of the foot and its covering, whether it be nail, or cloven hoof, or crust, we can hardly doubt: and an unexpected proof offers itself in the horse. Some rare instances are recorded of the foot of the horse having digital extremities. According to Suetonius, there was such an animal in the stables of Cæsar; another was in the possession of Leo X.; and Geoffroy St Hilaire states that he saw a horse with three toes on each of the fore-feet, and four on the hind.* In all these, the toes had nails, not hoofs. By such examples of deviation from the natural structure, it is made to appear still more distinctly, that a relation is established between the internal configuration of the fingers or toes and their coverings,—that when there are five complete, as in man, they are provided with perfect nails,when the number is two, as in the cleft foot of the ruminant, there are appropriate horny coverings,--and when the bones are reduced to form one, as in the horse, couagga, zebra, and ass, there is a hoof or crust.
In ruminants, there is the cannon-bone; but they have the * Such a horse was not long since exhibited in Town, and at Newmarket.
foot split into two parts, and that must add to the spring or elasticity. I am inclined to think that still another intention is manifest in this form of the foot: it first prevents it from sinking into soft ground, and then permits it to be more easily withdrawn. We may observe how much more easily the cow liberates her foot from the yielding margin of a river, than the horse; the solid, round, and concave foot of the horse is resisted, as it is withdrawn, by a vacuum or suction; while the split and conically-shaped hoof of the cow expands in sinking, and is easily extricated.
In the foot of the chamois, and other species of the deer tribe, there are two additional toes. These sketches show that
Foot of Antelope.
the metacarpal bones, (which in the horse are connected as splint-bones with the joint called the "knee,”) are here brought down near to the foot, and that each has its two pasterns, and coffin or ungual bone. The toes are braced by ligaments, which give great elasticity, as well as power of expansion, to
Foot of Reindeer.
the foot; and as a division of the flexor tendon runs to each, the spring must be increased as the animal starts from its crouching posture.
The two lateral toes of the hog are short, and do not touch the ground, yet they must serve to sustain the animal when the foot sinks. In the rein-deer, (fig. p. 64,) these toes are strong and thick, and by projecting backwards, expand the foot horizontally-thus giving the animal a broader base on which to stand, and, on the principle of the snow-shoe, adapting it to the snows of Lapland. These changes in the size, number, and place of the metacarpal and phalangeal bones, the systematic naturalist will call "gradations ;" I see only new proofs of adaptation,-of the same system of bones being applicable to every circumstance or condition of animals.
I have explained why the bones of the elephant's leg should stand so perpendicularly over each other; but there is also a peculiarity of structure in the bones of its foot. In the living animal, we see only a round pliant mass as a foot, resembling the base of a pillar, or that of the trunk of a stately tree. But when we examine the bones, we find the carpus, metacarpus, and phalanges applied to a very different use from what we have hitherto noticed; they are not connected with a moveable radius, and have no individual motion, as in the carnivorous animal-they serve merely to expand the foot, and give to the broad base of the column a certain elasticity.
In the sketch (page 40) I have placed the bones of the anterior extremity of the camel in contrast with those of the elephant. The camel's foot having no such disproportionate weight to bear as that of the elephant, lightness of motion is secured by the oblique direction of its bones, as well as by the position of the bones of the shoulder, which we have already noticed. But there is much to admire besides in the foot of the camel; although the bottom be flat and hard, like the sole of a shoe, yet, between the tendons and the horny sole, a cushion is interposed, so soft and elastic that the animal treads with the greatest lightness and security.
The resemblance of the foot of the ostrich to that of the camel has not escaped naturalists. In the bird, the same softness and pliancy of the sole are provided for by means resembling those in the quadruped, but by another adaptation of the
CLAWS OF CANINE AND FELINE TRIBES. CHAP. III.
frog or elastic pad.* We also have our pads; the best, though not the only, example of which is in the heel. The elastic struc
ture interposed between the bone of the heel and the integument, is neither ligamentous, nor cartilaginous, nor fatty, but a happy union of all; elastic fibres are so interwoven with the softer matter, that the cushion gradually yields to our weight, and rises as we step.
Attending still to the last bones of the fingers, let me point out once more how much may be accomplished, in bodying forth the whole animal, by the study of one of these bones. I allude to the dissertations of the President Jefferson and of Baron Cuvier, on the Megalonix. I must previously make some remarks on the mechanism of the claws in the lion.
Animals of the canine tribe, like those of the feline, are carnivorous, and both have the last bones of their toes armed with nails or claws. But their habits and means of obtaining food differ. The canine combine a keen sense of smelling with the power of continued speed; they run down their prey: the feline owe their superiority to the fineness of their sight, accompanied by patience, watchfulness, and stealthy movement; they spring upon their prey, and never long pursue it; they attain their object in a few bounds, and, failing, sulkily resume their watch. When we look to the claws, we see a correspondence with those habits. The claws of the dog and wolf are coarse and strong, and bear the pressure and friction incident to a long chase; they are calculated to sustain and protect the foot. But the tiger
A, the frog or elastic pad in the ostrich's foot. B, processes from the horn or cuticle, disposed like the hair
of a brush, and forming an adhesive and elastic sole.
leaps on his prey, and fastens his sharp and crooked claws in the flesh. Now, we must admire the mechanism by which they are preserved thus curved and sharp at their points. The last bone, that which supports the claw, is placed laterally to the next bone, and is so articulated with it that an elastic ligament (A) draws it back and to one side, and thus raises the sharp extremity of the claw upwards, and preserves it in that position. Whilst, therefore, the claw is
Apparatus of Lion's Claw.
retracted as into
a sheath between the toes, the nearer extremity of the furthest bone presses the ground, in the ordinary running of the animal. But when he makes his spring and strikes, the claws are uncased by the action of the flexor tendons; and in the Bengal tiger, they are so sharp and strong, and the stroke of his paw powerful, that they have been known to fracture a man's skull by a touch, in the act of leaping over him.*
*The pads in the bottom of the lion's foot are soft cushions, which add to its elasticity, and must, in some degree, defend the animal in alighting from his bound. I could not comprehend how the powerful flexor muscles did not unsheath the claws whenever the lion made his spring, and only did so when he was excited to seize and hold the prey; to detect the cause, I made the dissection from which the sketch has been taken. The last bone of the toe, from being drawn back by the elastic ligament (A) beyond the centre of motion of the last joint, is placed in so peculiar a relation to the penultimate bone, that when the
animal uses his foot in mere progression, the flexor tendon (B), although inserted into it, only acts in forcing the nearer end, and the cushion of the toe, to the ground. But when the lion strikes his prey to seize it, a more general excitement takes place in the muscles called interossei and extensors (D, E); the relative position of the two last bones is altered; the nearer end of the last bone is withdrawn from beyond the centre of motion of the joint, so that the action of the flexor tendon can now draw it forward or in a line with the penultimate bone,--and then the claw can be unsheathed, and prepared to hold or to tear.