66 FORM AND ACTION. 



no assistant is at hand to take up the fore-leg, to make the horse 

 stand firmly and itnmoveably upon the opposite one. 



While in a state of flexion, some degree of lateral motion is pos- 

 sessed by the cannon ; though the same no longer exists when the 

 leg is extended. Lateral motion, in the extended position of the 

 limb, could only have tended to diminish the stability and firmness 

 of the standing posture, without possessing any countervailing advan- 

 tage; but some degree of lateral mobility in the knee, in the flexed po- 

 sition of the limb — while the leg is in the air — enables the animal to 

 round and collect his action, and direct his foot while off the ground 

 and place it upon the ground, according as circumstances shall re- 

 quire of him. Some horses, we know, throw their feet outwards in 

 going ; some, inwards : foreign horses, especially, have the former 

 kind of action ; a good deal of which peculiarity in the flexion of 

 the leg is effected through the lateral motion possessed by the 

 knee-joint. 



LECTURE VI. 



THE FORE LEG OR CANNON. 



As the knee of the horse is the part which anatomically corre- 

 sponds to the wrist of man, so the fore leg, by the anatomist, is 

 compared with that part of the human hand which extends from 

 the wrist to the roots of the fingers ; the metacarpus, as it is tech- 

 nically called. Hence the three bones composing the fore-leg in 

 the horse are named, in accordance with the human metacarpus, 

 the metacarpal bones. Carrying comparisons and names so far 

 as this, however, appears, as Sir Charles Bell has aptly remarked, 

 " losing the sense in the love of system." " There is no regular 

 gradation," adds Sir Charles, in allusion to the many kinds of 

 formation discoverable in the limbs, and other parts of animals, 

 " but a variety most curiously adapting the same system of parts 

 to every necessary purpose." 



The metacarpal bones, those that compose the leg, are three 

 in number, viz. one large and two small. The large bone, one of 

 the cylindrical class, and one that is particularly straight and round 

 and smooth in its form, commonly goes by the name of the cannon 



