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CHAPTER II. 



STRUCTURES OF THE BODY. 



Bones — Cartilage — Muscles and Tendons — Ligaments — Connective Tissue 

 — The Nervous System. 



The frame-work of the body consists of the skeleton (Fig, 

 12), which is composed of a large number of connected 

 bones that are moved by muscles. We should, generally, 

 regard differences of length in the limbs, as those of muscles, 

 rather than of bones ; for the former are the producers of all 

 movements of progression, the latter aiding only in the 

 application of the force exerted. 



Bones. — The chief duties of bones in the act of pro- 

 gression are — (i) to "bear weight ; (2) to resist the effects of 

 concussion ; and (3) to act as levers. Capability for per- 

 forming (i) and (2) is dependent on conditions of texture 

 (** quality '*), size (" substance''), and arrangement. 



Quality and substance of bone. — Whether the animal be 

 intended to carry heavy burdens, or to gallop over hard 

 ground, it is always a matter of the greatest importance 

 that his bones, especially those below his knees and hocks, 

 should be of strong and compact texture. It has been 

 customary to state, in a vague way, that the bones of Arab 

 horses and English thoroughbreds are denser than those of 

 other breeds. It would, however, be more exact to say that 

 the drier the soil on which a horse has been bred and 

 brought up, and the ^'harder'' the food upon which he has 



