THK HORSE IN MOTION. 53 



they are all placed beyond the control of the will. If it yields too 

 much, the fetlock is liable to strike the ground ; if it is too rigid and 

 it does not yield enough, there will be stiffness and a hobbling gait. 

 \Ve shall have occasion to refer to this again when we analyze the 

 paces. 



There is no one fact, brought out by the experiments of Mr. Stan- 

 ford with instantaneous photography, of more interest than the action 

 of the suspensory ligament. 



When the horse is standing, it will be seen that the pastern forms 

 an acute angle with the metatarsus. Its position indicates the length 

 of the ligaments, and it is their resistance that prevents the further 

 extension of the joint ; but in running and fast trotting, this ligament 

 is put upon the stretch, when the limb is shortened by the weight of 

 the body, to such an extent that the pastern is made to take a position 

 at right angles to the metatarsus and horizontal with the ground. (See 

 the plates of horses speeding, passim.) Elongation of the limb begins 

 immediately after the perpendicular is passed, and as the fetlock was 

 the last joint to reflex in shortening, so it is the first to recover its 

 normal extension. This spring continues its action during the rest 

 of the stride, straightening the fetlock joint as the leg becomes elon- 

 gated after the passage over it of the centre of gravity, still sustain- 

 ing the body with undiminished force until it leaves the ground, when, 

 being relieved from the superimposed weight, the flexor muscles re- 

 gain control ; and it is the reaction of these ligaments, with that of 

 the flexor tendons acting as ligaments, that produces the quick move- 

 ment, quicker than is possible in muscular contraction, which causes 

 the feet to throw dirt ; it is effected after the weight is off the foot 

 and the propulsive effort is complete. There is no muscular action 

 en the foot until after the pressure is removed and the flexors regain 

 control. 



It is an exceedingly difficult problem to determine the absolute, or 

 even the relative, work performed by the different muscular powers 

 employed in locomotion. There are many different elements entering 

 into the calculation, that are impossible to be weighed. Muscles 

 differ in quality as well as quantity ; some contain a larger proportion 



