354 BODY CONTROL AND HABIT FORMATION 



Diagram of the nerve path of a simple reflex action. 



exerted, nor are intelligent acts performed. All acts performed in 

 such a state are known as reflex actions. The involuntary brush- 

 ing of a fly from the face, or the attempt to move away from the 



source of annoyance 

 when tickled with a 

 feather, are examples 

 of reflexes. In a 

 reflex act, a person 

 does not think before 

 acting. The nervous 

 impulse comes from 

 the outside to cells 

 that are not in the 

 cerebrum. The mes- 

 sage is short-circuited 

 back to the surface 

 by motor nerves, without ever having reached the thinking 

 centers. The nerve cells which take charge of such acts are lo- 

 cated in the cerebellum or spinal cord. 



Automatic Acts. — Some acts, however, are learned by con- 

 scious thought, as writing, walking, running, or swimming. Later 

 in life, however, these activities become automatic. The actual 

 performance of the action is then taken up by the cerebellum, 

 medulla, and spinal ganglia. Thus the thinking portion of the 

 brain is relieved of part of its work. 



Bundles of Habits. — It is surprising how little real thinking we 

 do during a day, for most of our acts are habitual. Habit takes 

 care of our dressing, our bathing, our care of the body organs, our 

 methods of eating ; even our movements in walking and the kind 

 of hand we write are matters of habit forming. We are bundles of 

 habits, be they good ones or bad ones. 



Habit Formation. — The training of the different areas in the 

 cerebrum to do their work well is the object of education. When 

 we learned to write, we exerted conscious effort in order to make 

 the letters. Now the act of forming the letters is done without 

 thought. By training, the act has become automatic. In the 

 beginning, a process may take much thought and many trials 



