94 KENNEL SECRETS. 



Underrating the value of exercise to himself he is far 

 from likely to form a correct estimate of its importance in 

 animal life unless it is literally forced upon him, and espe- 

 cially reluctant is he to accept the truth when conviction 

 means some sacrifice of his convenience, as it generally 

 does where dogs are involved. 



Considering all this, the writer feels it his duty to dis- 

 cuss at considerable length the specific effects of exercise, 

 the evils of too close confinement and the means by which 

 dogs may be held in check and yet suffer much less injury 

 than is generally inflicted by restraint. 



Glancing at the physiology of exercise there first appears 

 the fact that a very large part of the body consists of mus- 

 cular tissue, in which is contained nearly one-quarter of 

 the blood, and by it fully one-fourth of the nerve energy 

 stored up in the body is turned into work. This tissue 

 is made up of single muscles, the number of which in the 

 dog is not accurately known, but as there are over five 

 hundred in the human body it is fair to assume that this 

 number is not very greatly in excess of that in all the 

 higher order of animals. Every muscle has blood-vessels 

 and nerves, and fresh blood is supplied its substance by 

 the heart through its arteries and the fine network of 

 small vessels formed by a minute subdivision of them. 

 These small vessels open into and are continuous with 

 veins of about the same size, and they in turn are united 

 into larger and larger vessels that finally connect with 

 the channels by which the blood is returned to the 

 heart. 



Once a muscle begins working the blood stream pass- 

 ing through it becomes swollen and presents decided 

 changes in quality. The blood which enters is bright 

 red in color, rich in oxygen and poor in carbonic acid, 

 while that which leaves it is dark blue in color and of a 



