The Leap.—The leap is an act by which the body is wholly raised from the ground and projected upwards and forwards to a greater or less distance.
It is prepared for by the flexing of the hind-limbs, which, by being suddenly extended, project the body, and thus enable it to pass over an obstacle.
Fig. 137.—Leap of the Hare (after G. Colin).
This preparatory arrangement is very remarkable in the leap of the lion, the cat, and the panther, which execute springs of great length; in the horse, in which the leap is not an habitual mode of progression, this flexion of the hinder limbs is less marked. With this animal the leap is generally associated with the gallop; nevertheless, it is sometimes made from a stationary position. In observing the hare or the rabbit, in which the leap is habitual, we notice ([Fig. 137]) that the hind-limbs, being extremely flexed, rest on the ground as far as the calcaneum, are then straightened by the action of their extensors, become vertical and then oblique backwards at the moment the body is thrown forward into space by the sudden extension of these limbs.
The action of the extensors is energetic and instantaneous, and their energy is greater than in ordinary progression, for it is required to lift the body and to project it forcibly a more or less considerable distance. It is the extreme rapidity of this action which enables the animal to clear an obstacle, for without this condition the body would be raised, but not separated from the ground.
First of all, in reaching the obstacle to be cleared, the horse prepares to leap by taking the attitude of rearing; the hind-limbs are flexed and carried under the body, the fore-quarters are raised, and the different segments of the fore-limbs are flexed ([Fig. 138]).
