ELEMENTS OF HIPPOLOGY. 115 



upper front bone that is so deeply grooved in the cuts. The bone 

 near the numbers (1, 2, 3, and 4), standing back of the others, is 

 the sixth bone referred to, and is the bone that forms the promi- 

 nence in rear of the hock. The true hock-joint is between the 

 upper bone of the five and the leg-bone; most of the motion of 

 the hock is about this joint, and it is seldom diseased. The 

 other four bones have smaller motions among themselves, but 

 their principal function is to lessen, by the elasticity of their 

 cartilages, the shock of impact. 



The properly shaped hock is clean in its outline, with its 

 angularities well defined. The point of the hock should be 

 prominent, and the depressions in front of it should be pro- 

 nounced; there must be no puffiness about this joint. 



The bones are covered with membranes that secrete fluids 

 necessary for their building up and preservation. The carti- 

 lages between the bones possess most of the chemical elements 

 of the bones themselves, except the lime and other salts that 

 give the bones their rigidity and strength. When the mem- 

 branes or cartilages are injured through any cause, inflamma- 

 tion sets in, and the functions of secretion are stimulated. As 

 a consequence, more of the bone salts are secreted than are 

 needed for the maintenance of the bones, and the excess is de- 

 posited on the outside, in the form of rough nodules that invade 

 the spaces needed for the proper working of the ligaments and 

 tendons of the joint, or in the tissues of the cartilages, which 

 thereby loose their elasticity and become bone. This deposit 

 may go on until the joint is destroyed by the excess bony de- 

 posit cementing the bones together. 



In the hock- joint there is a great change in the direction of 

 the energy developed in the propelling muscles, and everything 

 connected with the joints should work smoothly to get the best 

 results. Any strain due to excessive concussion is apt to set up 

 inflammation between the lowest bones of the hock and the 

 head of the cannon-bone. This inflammation, if not stopped 



