HOW DO WE CONTROL THE HUMAN MACHINE? 391 



Rest and Health. Our days should be made up of 

 work and play, rest and sleep. It is just as bad to over- 

 exercise as it is to underexercise. One should remember 

 that all machines need rest, and the human machine is no 

 exception to the rule. At least eight hours of sleep should 

 be had by every boy and girl of high school age, and nine 

 or ten hours of sleep by younger children. Fewer movies 

 and more quiet reading at home would be good for every 

 boy and girl. Moderation in all things is a good rule. 

 Overstrain of any kind brings on fatigue, and in the end 

 shows that we cannot strain an organ without paying for 

 it. If we overstrain the eyes, for example, we pay for it 

 by wearing glasses later. If we overstrain in athletics, 

 we may have to give up athletics altogether. Overfatigue 

 by keeping too late hours will surely call us to account 

 later in life. Let us learn while young the value of com- 

 plete relaxation, and let us, while we are growing, get the 

 habit of going to bed at the proper hour. 



Fair play in running your own machine will result in 

 your being well and happy and then you will feel like 

 being fair to others. 



SELF-TESTING EXERCISE 



Select from the following list those words which best fill the blank spaces 

 in the sentences below and arrange the words in proper numerical order. 

 A word may be used more than once. 



tendons thinking sheath 



stimulations blood vessels autonomic 



sense muscles outward 



suprarenal brain control 



endocrine movements thyroid 



motor breathing inward 



sensory cord nerves 



The nervous system has the (1) of the human machine. 



There is a central part made up of the (2) , spinal (3) , out- 

 going (4) , and another portion which consists of certain (5) 



organs like the eye or organs of taste, with nerves which lead 



