THE REGULATING MECHANISM 209 



constitute a reflex mechanism ; this appears 

 to be the general plan on which the whole 

 nervous system is constructed. 



121. This fact is illustrated by associated 

 movements, such as those of speech or of the 

 hand in penmanship. A spoken word rouses 

 the auditory centre ; this transmits an impulse 

 to the motor centres of the speech mechanism ; 

 and the word may be audibly repeated. Or 

 the message from the auditory centre may 

 reach the centres for the ringers and arm of the 

 right hand and the word spoken may now be 

 written. Again, the sensory impressions may 

 come from the eye to the visual centre, and it 

 in turn may excite speech or the movements of 

 the ringers and hand. These impulses may 

 be also transmitted to parts of the cerebrum 

 and give rise to consciousness. Sometimes in 

 disease one of the links in this physiological 

 chain may be broken. A patient suffering 

 from some form of cerebral disease, when asked 

 the question, " What is your name ? " may be 

 unable to answer, not because he does not 

 hear (he is not deaf), but because he cannot 

 utter the words " John Smith " in response, 



