In the upper segment, or thigh, the difference between the two limbs is seen to be, to a certain extent, the reverse of what it is below. That is to say, whereas, in the HORSE, the _toe_ is elongated and thickened, so as greatly to exceed the corresponding part of the human limb; in MAN the _thigh-bone_ is elongated, so as to be double the length of that of the horse; the thigh-bone in man is also placed more vertically, nearly in the plane of gravity of the trunk. The horse’s thigh-bone slants forwards and outwards, which gives the muscles great power by causing them to run more at right angles between their points of attachment; and this arrangement increases the strength of the animal in drawing weights, and facilitates springing. A man cannot spring without first bending the limbs a little; whereas a horse, or a goat, can spring, at once, from the position in which it is standing. To revert to the anatomy of the Human Foot. _The Arch of the Foot._ The seven tarsal and the five metatarsal bones--that is, the twelve bones of the instep--are arranged and jointed together so as to form an arch from the point of the heel to the balls of the toes. This is called the “plantar arch,” from the Latin word _planta_, the sole of the foot. The _astragalus_ forms the summit, or key-bone, of the arch. It receives the weight from the leg, and transmits it, through the hinder pillar of the arch, to the heel, and, through the front pillar of the arch, to the balls of the toes. [Illustration: Fig. 6.] The drawing represents a section, from behind forwards, of the lower end of the leg-bone, and of the bones lying along the inner side of the plantar arch. Behind it extends through the heel-bone, and in front through the great toe. It exhibits the arrangement of the fibres and plates in the interior of the bones, and shows that the greater number of them, in each bone, follow the direction of the two pillars of the arch; that is to say, they descend from the summit of the arch where it supports the leg-bone, backwards and downwards, to the heel, and, forwards and downwards, to the balls of the toes. Their arrangement is, therefore, such as to give resisting strength to the bones in the directions in which it is most required.