22 4 



OUR BODIES AND HOW WE LIVE 



We are not so independent in our daily actions as one 

 would at first think. . Ten thousand unconscious acts take 

 place which tend to govern and preserve our health. We 

 have as little control over them as we have over the stars 

 above us. 



301. Familiar Examples of Reflex Action. Let us call to 

 mind a few familiar examples of reflex action. If our feet 



slip on the ice, with- 

 out the effort of the 

 will the body tends 

 to recover itself. The 

 mind does not always 

 act, at least in the 

 ordinary way, to pull 

 the fingers away when 

 they touch a hot stove. 

 We try to brush the 

 flies away when we 

 are asleep. 



By an effort of the 

 will, we can stop our 

 breath for a moment 

 or two ; but soon the 

 call for air is impera- 

 tive, and the order 

 must be obeyed, whether we will or no. The great work 

 of digestion is going on day after day, but we have no 

 control over its complicated movements. 



Experiment 67. To illustrate reflex action. Tickle the inside of 

 the nose with a feather. This does not interfere with the muscles of 

 breathing, but by reflex action they come to the help of the irritated 

 part, and provoke sneezing to clear and thus protect the nose. 



FIG. 141. Dental Branch of One of the 

 Divisions of the Fifth Pair of Cranial 

 Nerves, supplying the Lower Teeth. 



Branches from the motor root, distributed to 

 various muscles, are also shown. 



