iO ANATOMICAL CONSIDERATIONS. 



being joined, by osseous union, may give solidity to the part ; but it must 

 be self-evident the cliain possesses no inherent power to sustain the 

 smallest pressure. Therefore, the body of the rider, when placed upon 

 the back, cannot be upheld by bone alone. The weight must repose 

 upon the muscles and the ligaments by which the solid parts are kept 

 together. Man, therefore, when mounted upon a horse, is seated upon 

 elastic substances, animated by the powers of vitality. This circumstance 

 readily accounts for the pleasurable feelings and the lightness of spirit 

 communicated to the master when within the saddle; although the deli- 

 cacy of the structures on which the burden is cast should also instruct 

 that an elaborately and a delicately organized body ought to be shielded 

 from labor until age has confirmed and strengthened the several portions 

 of the frame. 



When contemplating the uses for which the quadruped was created, 

 we perceive the necessity of that huge mass of muscular fiber with which 

 the back is cushioned. We also recognize the beauty of intention which 

 those numerous supports, called ribs, embody and declare. These props, 

 eighteen on either side, must greatly strengthen the main structure, 

 although each is of a loose texture, and every one is more or less pliable. 

 The innate property of elasticity belonging to the horse's ribs seems to 

 have been long known to country urchins, who, out of these bones, have 



/ 



THE THORAOIO FBAMEWOKK OF THE HOKSE. 



Showing the manner in which the ribs spring from the spine to unite upon the Ixine of the breast. 



been accustomed to form bows whence to propel juvenile arrows. Na- 

 ture, however, seems not to have been satisfied with this provision, for 

 the inferior portion of the ribs consists of cartilage, which anatomists 

 speak of as the most elastic substance in the body; this yielding termin- 

 ation rests on the sternum or breast-bone, a structure more than three 

 parts of which are composed of the last-named material. 



The manner in which the fore limb is united to the trunk likewise 



