32 THE HORSE IN MOTION. 



During the life of the animal the tenacity of the muscle is greater 

 than that of its tendon, but when vitality no longer animates it it may 

 be easily torn. 



While the articular ligaments are subject to extension and elonga- 

 tion by early use and frequent tension, so that greater freedom of 

 motion than, is normal is acquired, it is otherwise with the muscular 

 tissue and its tendons. By exercise within certain limits, at regular 

 intervals, and with proper nutrition, the thickness and power of the 

 muscles may be increased, and by neglect of these conditions they will 

 become thin and pale, while contraction will be feeble and not well 

 sustained ; but they will not become elongated under whatever violent 

 and long-sustained exercise ; they may increase in thickness, but not 

 in length. But for this exception to the rule the whole plan on which 

 animal mechanics was founded would have fallen to the ground with 

 the animal himself. Were the muscles to become lengthened by use 

 without corresponding increase in length of levers, the tension neces- 

 sary to prompt action would be lost, and the effect would be similar 

 to that upon the tiller ropes of a ship were they to become relaxed. 

 What would be the effect upon the length of the bones in the period 

 of time contemplated by some it is useless to inquire, but we know 

 that the increase of muscular power by increase in the bulk of the 

 muscle takes place in a short period, and in the lifetime of the indi- 

 vidual. But while the muscles and their levers will retain their nor- 

 mal relation of length during life in a healthy subject, that balance is 

 sometimes lost as the result of injury. A child has been run over by 

 a wagon ; the wheel has passed over the muscles of the calf so as to 

 disorganize the muscular tissue; in due time the injured part is re- 

 stored to health, but the muscle does not develop fully ; it is shortened, 

 and a form of club foot is the result, in which the person cannot, while 

 walking, reach the ground with the heel. The child has grown to 

 manhood, but no amount of use and no length of time will elongate 

 the muscle. Nature cannot elongate that muscle without anarchy. 

 The Creator works by law, and to claim an exception is virtually an 

 admission that we do not understand the law. But what He cannot 

 do without anarchy his creature can ; he slips a tenotomy knife 



