THE NERVOUS SYSTEM 295 



receives messages that come to the brain, and the brain 

 sends out impulses which cause certain of our muscles to 

 contract; by this means we are enabled to act in any 

 way we desire in regard to objects in the world about us. 

 Through the function of the nervous system in conducting 

 impulses from one part of the body to another the activities 



FIG. 211. Cerebro-spinal nervous system. 



of different organs are made to harmonize or, as physiolo- 

 gists say, become coordinated. Were it not for some 

 conducting system one arm might act quite contrary to 

 the other arm, and each leg might not act in harmony 

 with the other one in walking, and our other organs 



