200 THE EXTERIOR OF THE HORSE. 



S. Phase of Elevation. In these phenomena the foot leaves 

 the soil, oscillates forward, and then assumes a point of contact. The 

 line of direction of the member is first inclined backward, and after- 

 wards obliquely forward. The posterior column, like the anterior, 

 should successively become shortened, elongated, and prepare itself for 

 station. 



1 . Shortening. This process presents the following stages : a. 

 Maximum flexion of the pastern and slight flexion of the canon and 

 the thigh, producing a marked elevation of the foot and a maximum 

 flexion of the fetlock, which, however, is only feeble in the hock, the 

 stifle, and the hip (0 to 1). b. Very marked flexion of the canon and 

 the femur, with an accentuated closing of all the articular angles except 

 that of the fetlock, which commences to open itself by the extension 

 of the phalanges (1 to 2). 



2. Elongation of the Member. The elongation commences by 

 the extension of the fetlock, to be continued by that of the hock and the 

 stifle from the sole influence of the extension of the tibia on the tarsus 

 (2 to 4). The coxo-femoral angle has now reached its minimum size. 



Before the foot again reaches its point of contact, the angles of 

 the stifle, the hock, and the fetlock have reached their limit of extension 

 almost entirely under the influence of that of the leg, which itself has 

 attained this limit of movement. The pastern, which now tends to 

 become horizontal (4) again, thus carries the hoof far. in advance. 



All these are conditions of structure more or less closely allied to 

 the production of force or speed, and these we shall examine in the 

 pages that follow. We shall also demonstrate that the animal motors 

 can be submitted with the greatest accuracy to the same scientific analy- 

 ses, according to mechanical principles, as the inanimate motors which 

 are the production of human ingenuity. 



CHAPTER I. 



ANTERIOR MEMBER. 



THE anterior member comprises several regions which we describe 

 in the following order : the shoulder, the arm, the forearm, the elbow, 

 the knee, the canon, the fetlock, the footlock, the ergot, the pastern, the 

 coronet, and the foot. 



