THE HORSE IN MOTION. 



93 



In Fig. 7 the left hind foot is supporting the weight, and already the 

 centre of gravity has passed over it, while the right, relieved from that 

 duty, is exercising its function as a propeller, and the right fore leg 

 is reaching forward to take the ground as far as possible in ad\'ance ; 

 the foot is extended to bring the heel, with its elastic cushion, first in 

 contact. The left fore leg is straightening to take its place in the 

 order of succession. 



Fig. 8. 



The right hind leg has given its final propulsive impulse in Fig. 8, 

 and the tensor vaginae femoris, the iliacus, sartorius, and superficial 

 gluteus are in the act of flexing the stifle and advancing the leg to 

 a new position. The left hind leg has passed the perpendicular, and is 

 no longer in a position to give much aid as a supporter to the centre 

 of gravity; but the right fore foot has reached the ground, and takes 

 its position as a supporter of the weight of the body, dividing the 

 burden with the left hind leg still upon the ground. 



In the last chapter it was shown how the limb is thrown forward 

 into this position, and how the shock of contact is transmitted, through 

 the straightened extremity, to the humerus and scapula ; and unneces- 

 sary flexion of the elbow and shoulder joints is prevented by the tri- 

 ceps of the arm and superspinatus muscles, while it continues to give 

 uniform support to the body, at the same time that it shortens by the 



