THE SPINE. 165 



now proceed to that portion of the spine wliich forms the roof of the e])L"5t 

 and belly. It consists of twenty-three bones from the neck to the hauncn ; 

 eighteen, called dorsal veterhrce., composing the back; and five lumbar vcr- 

 tebrcc, occupying the loins. On this part of the animal the weight or bur- 

 den is laid, and there are two principal things to be considered, easiness of 

 carriage and strength. If the back were composed of unyielding materials, 

 if it resembled a bar of wood or iron, the jar or jolting, in the rapid motion 

 of the animal, could not possibly be endured. To avoid this, as well as to 

 assist in turning, the back is divided into num.erous bones ; and betweea 

 each pair of bones, there is interposed a cartilaginous substance, most highly 

 elastic, which will yield and give way to every jar, not so much as to 

 occasion insecurity between the bones, or to permit considerable motion 

 between any one pair; yet forming altogether an aggregate mass of elas- 

 ticity, so springy that the rider shs almost undisturbed, however high may 

 be the action, or however rapid the pace. 



Strength is as important as ease ; therefore these bones are united togeth- 

 er witii peculiar firmness. The round head of one is exactly fitted to the 

 cup or cavity of that immediately before it ; and between them is placed 

 the elastic ligamentous substance we have just described, so strong, that in 

 endeavouring to separate the bones of the back, the bones will break sooner 

 than this substance will give way. Beside this there are ligaments run- 

 ning along the broad under surface of these bones; ligaments between each 

 of the transverse processes, or side projections of the bones; and ligamenty 

 between the spinous processes or upright projections; and a continuation of 

 the strong ligament of the neck, running along the whole course of the 

 back and loins above these, lengthening and contracting, as in the neck, 

 with the motions of the animal, and forming a powerful bond of union 

 between the bones. 



By these means the hunter will carry a heavy man without fatigue or 

 strain through a long chase ; and those shocks and jars are avoided which 

 would be annoying to the rider, and injurious and speedily fatal to the horse. 



These provisions, however, although adequate to common or even severe 

 exertion, will not protect the animal from the consequences of brutal usage; 

 and, therefore, if the horse be much overweighted, or violently exercised, 

 or too suddenly pulled upon his haunches, these ligaments are strained: 

 inflammation follows ; and the ligament becomes changed to bone, and the 

 joints of the back lose their springiness and ease of motion ; or rather in 

 point of fact cease to exist. On account of the too hard service required 

 from them, and especially before they have gained their full strength, there 

 are few old horses, that have not some of the bones of the back or loins 

 ancliylosed, united together by bony matter, and not by ligament. When 

 this exists to any considerable extent the horse is not pleasant to ride; he 

 turns with difficulty in his stall ; he is unwilling to lie down, or when down 

 to rise again; and he has a curious straddling action. Such horses are 

 said to be broken backed, or chinked in the chine. 



Fracture of the bones of the back rarely occurs, on account of their 

 being so strongly united by ligaments, and defended by muscular substance. 

 If a fracture of these bones does happen, it is during the violent struggles 

 after the horse has been cast for an operation. 



The length of the back is an important consideration. A long-backed 

 horse will be easy in his paces, because the increased distance between the 

 fore and hind legs, Avhich are the supports of the spine, will afford greater 

 room for the play of the joints of the back. A long spring has much more 

 play than a short one, and will better obviate concussion. A long-backed 

 horse is likewise formed for speed, for there is room for him to bring hia 



