314 COORDINATION AND SENSATION 



through the central system ; and third, from the central 

 nervous system to the active tissues of the body. 



Their chief differences are to be found, first, in the path- 

 ways followed by the impulses, which are through the cere- 

 brum (the organ of the mind) in voluntary action, but in 

 reflex action are only through the spinal cord or the lower 

 parts of the brain ; and second, in the fact that voluntary 

 action is under the direction of the mind, while reflex action 

 is not. It would seem, therefore, that the statement some- 

 times made that "voluntary action is reflex action plus the 

 mind" is not far from correct. Mind, however, is the im- 

 portant factor in this kind of action. 



Secondary Reflex Action. Everyday experience teaches 

 that any voluntary action becomes easier by repetition. A 

 given act performed a number of times under conscious 

 direction establishes a condition in the nervous system that 

 enables it to occur without that direction and very much as 

 reflex actions occur. Actions of this kind are known as 

 secondary reflex actions, or as acquired reflexes. Walking, 

 writing, and numerous other movements pertaining to the 

 occupation which one follows are examples of such re- 

 flexes. These activities are at first entirely voluntary, but 

 by repetition they gradually become reflex, requiring only 

 the stimulus to start them. 



The advantages to the body of its acquired reflexes are 

 quite apparent. The mind does not have to attend to the 

 selection and direction of stimuli and, to that extent, is left 

 free for other work. A good example of this is found 

 in writing, where the mind apparently gives no heed to 

 the movements of the hand and is only concerned in 

 what is being written. The student will easily supply 

 other illustrations of the advantages of secondary reflex 

 action. 



