306 STABLE ECOxVOMY. 



but the surcingle now used acts altogether upon the chest, 

 which training ought to expand rather than contract. 



State i>f tke Muscles. — Exertion, under certain regulations, 

 produces a particular state of the muscles, the parts of mo- 

 tion, and of the nerves, the blood, and the blood-vessels, by 

 which the muscles are supplied. Neither anatomy nor physi- 

 ology is able to describe the change which those parts under- 

 go in training. The eye, indeed, discovers a difference in 

 the texture and the color of the muscles. Those which have 

 been much in use are redder, harder, and tougher, than those 

 that have had little to do. They contain more blood, and 

 that blood is of a more decided red color. They are also a 

 little larger, when compared with a corresponding muscle of 

 less work. More than this dissection does not reveal. It is 

 known, without any dissection, that the instruments of mo- 

 tion exist in different states ; that in one state their action 

 is slow and feeble ; in another state it is rapid and powerful ; 

 and that in certain states they can maintain their action for a 

 much longer time than in certain other states. 



For practical purposes it is not perhaps of much conse- 

 quence to learn all the changes which the muscles, the blood, 

 the blood-vessels, and the nerves, must undergo, before the 

 horse can possess the condition which his work demands. It 

 may be enough to know that the condition, in whatever it 

 may consist, can be conferred only by exertion. There are 

 numerous auxiliaries, and various modes of giving and of 

 regulating exertion ; but until it has produced the requisite 

 alteration in the muscles, and their appendages, there can 

 never be any remarkable degree of speed nor endurance. 



State of the Breathing. — I have said that the horse's breath- 

 ing can not be free so long as a large belly interferes with the 

 action of the lungs. To lighten a large carcass is to improve 

 the wind. But I am persuaded that the lungs themselves may 

 imdergo a change particularly favorable to protracted exertion. 

 Though I can not offer any proof of this, I think the alterations 

 which take place in other parts of the body mnke it appear 

 probable that the lungs also are altered. It is reasonable to 

 suppose that the tubes which carry the blood, and those which 

 carry the air, suffer some increase of calibre ; and that the 

 lungs taken altogether, become a little larger. Such an al- 

 teration seems necessary to account for the visible change 

 which takes place in the breathing. As training proceeds, 

 the horse becomes less and less distressed by exertion, 

 and ultimately acquires the power of doing that which 



