72 GENERAL SCIENCE 



of circulation to the special organs by which it is eliminated from the 

 body. 



The great value to health of suitable exercise lies in an increased 

 activity of the cells, a larger supply of nourishment brought to them, 

 and a more complete riddance of the waste of the body from the cells 

 and tissues. 



The brain as organ of the mind requires nourishment, exercise, and 

 freedom from exhaustive labors for its growth and activities even as 

 other parts of the body. 



The need of rest for the human body, including those periods of 

 sleep when complete relaxation should occur, results from the fact that 

 the human body does not rebuild its cells rapidly enough, nor provide 

 energy sufficiently fast, to make good the waste of the body in its 

 hours of activity. 



Recreations may be considered as including all those occupations 

 where the general results are restful. Recreation ranges in character 

 from what is done solely as amusement to what is merely a change in 

 form of labor. This latter is restful because it calls into use activities 

 of the body before unused, thus freeing those parts which have become 

 wearied. 



STIMULANTS AND NARCOTICS 



There is a certain rate at which an engine or dynamo does 

 its best work, and where there is the least wear. Both its 

 efficiency as a machine and its length of life as a working 

 agent require that it be run at its normal capacity. To 

 overload a dynamo or a steam engine, or to speed either 

 beyond a normal rate, means its destruction. The human 

 body in spite of its recuperative powers suffers from the wear 

 and waste of an unnatural strain put upon it in the use of 

 alcoholic drinks, and sooner or later breaks down. The vital 

 organs are affected seriously, and it is upon them that length 

 of life and vigor of health largely depends. One may live 

 long and be an active agent in the affairs of life after the 

 system is incapacitated for hard muscular labor; but there 

 is always a need for vigorous heart action, active nutritive 

 processes, and healthy action of kidneys and lungs. The 



