44 THE HUMAN BODY. 



the fibers of voluntary muscle; and they are broad in the 

 middle, and taper to each end. They have no cross-stripes, 

 and have a spot in the center called a nucleus. 



MUSCULAR EXERCISE. 



SECTION IV. 1, It is a law of Nature, that every liv- 

 ing thing, in order to remain in health, must do the thing 

 that it was made to do. A stone was made to lie inactive 

 and motionless. Men, as well as the lower animals, were 

 nmde for activity and motion. Every part of the body 

 must do the work that it was made to do. The muscles 

 must move, the stomach must digest, the nerves must be 

 in use, the brain must think. The part which is allowed 

 to remain inactive becomes unhealthy and weak. This is 

 the great law of exercise. 



2, This law applies especially to young persons. After 

 the body has got its growth, and has become firm and 

 strong, it can endure bad usage or neglect better than in 

 the growing period. 



3, Some people are engaged in occupations which give 

 abundant exercise to all the organs of body and mind. 

 Such occupations tend to long life. Statistics kept in the 

 State of Massachusetts for thirty years, of the length of 

 life in different occupations, showed that the farmers lived 

 the longest. 



4, Many employments require the use of the muscles 

 more than of the brain. Persons engaged in such em- 

 ployments should, during their hours of recreation, exer- 

 cise their minds. 



5, Other occupations engage the mind while the body 

 is inactive. Those who have such occupations should 

 seek recreation in muscular exercise. 



