POSTERIOR MEMBER. 267 



effect. Nothing is more common than to witness, at the base of 

 elbowed hocks, the development of osseous tumors, which are the 

 expression of the excess of its function, to which such hocks are pre° 

 disposed from the very fact of their defective conformation. We can 

 understand that this defect will tend to become more exaggerated 

 when the hock, instead of corresponding to the vertical through the 

 buttock, is situated farther under the centre of gravity. Horses 

 whose hocks are angular are often animals of superior quality so far 

 as energy for work is concerned, and are, consequently, predisposed to 

 ruin themselves so much more quickly, as the apparatus upon which 

 they apply their force possesses less favorable conditions for resistance." 



The learned author of this quotation might have added that the 

 angular hock, by drawing the inferior })art of the member towards the 

 centre of gravity, by causing an exaggerated closing of the tibio-tarsal 

 angle and too great a stretch of the foot forward under the trunk, 

 determines, besides, an overloading of the posterior members prejudicial 

 to their functions. It augments the work of the extensor muscles of 

 the metatarsus during station, diminishes the amplitude of the step by 

 restraining the movement of flexion, and, finally, expends to no pur- 

 pose a part of the effort of impulsion to elevate the trunk instead of 

 carrying it directly forward. 



Such a hock should, for these reasons, be rejected in spite of its 

 apparent width, for it is the result of an imperfection in the axis of 

 the member which will soon ruin it. 



c. The Canon, Oblique downward and backward. — This 

 direction of the canon places the posterior member in the attitude 

 which is called camping, and which approaches somewhat that of the 

 animal when he urinates. We will have occasion to return to this in 

 discussing the axes. Let us say, for the present, that it places the 

 members in a very unfavorable condition to fulfil, with ease, their 

 functions as columns of support and as agents of impulsion, relatively 

 to the trunk. It removes them too far from the centre "of gravity, 

 transfers a corresponding portion of the body-weight upon the anterior 

 members and the loins, and renders the impulsion more feeble and less 

 extensive ; it predisposes to gliding backward, fatigues the animal 

 more, leads to sway-backedness, etc. (See Axes.) 



We must not confound this conformation with that which is proper 

 to a straight hock. The femoro-tibial and tibio-tarsal angles, in the 

 latter case, are open, but the natural axis of the limb is preserved, 

 while, in the horse camping behind (only from the hock down), the 

 tibia remains very oblique, whilst it leaves the tibio-tarsal angle very 



