POSTERIOR MEMBER. 265 



remarked, "when the pieces of a freshly-dissected hock are moved, 

 it is easy to recognize that, towards the limits of its movement of 

 extension and flexion, the angle opens and closes by a sort of spring- 

 like action, which cannot be better compared than to that of the blade 

 of a pocket-knife upon its handle. The articulation, being once opened, 

 the two segments will remain in this state of extension by the very fact 

 of the manner of coaptation of their surfaces of contact, and the 

 intervention of a muscular force .to maintain them vertically is not at 

 all necessary." 



The straight hock, finally, possesses this advantage from a point of 

 view of speed, that it is usually associated with long posterior members 

 capable of taking long steps. Supposing the lengths of the crural, 

 tibial, and metatarsal segments to be equal, it is evident that their 

 superposition, in a more or less vertical manner, will give a more con- 

 siderable total height to the member than if these pieces are joined in 

 a more oblique manner. Whence it follows that a horse having his 

 bones thus articulated will have his locomotory apparatus more 

 developed relatively to the body, and hence will be endowed with 

 greater speed. 



2d. The Tibia, Oblique. The first eifect of such a direction 

 is the closing of the tibio-tarsal angle, allowing less freedom to the 

 movements of flexion than if this angle were more open. Another 

 effect is a more perpendicular insertion of the cord of the hock, which 

 places the latter in the best conditions for the proper utilization of its 

 force. The last result is a lessening of the total length of the posterior 

 member and a proportionate diminution of the aptitude of the organism 

 in relation to speed. 



Thus conformed, the animal is closer to his base of support ; the 

 hock is strong, and its muscles well disposed ; but the step is shorter 

 on account of the smallness of the tarsal angle and the diminished 

 length of the member. All things being equal otherwise, the gait will 

 be less rapid, unless it makes up by the repetition of its movements 

 for the space and time lost at each stride, which will fatigue the ani- 

 mal and wear him out more quickly ; but if the step lacks amplitude 

 and the member length, the muscles may be more voluminous, the 

 body developed, and the total mass considerable. The animal being 

 then capable of the most energetic efforts at a very slow pace, the 

 quantity of movement (mv) produced will not be less, because it will 

 displace a greater weight with more feeble velocity. Poorly adapted 

 for the turf, he will be excellent for traction, provided that his confor- 

 mation has been modified in the sense which we have indicated. 



