EFFECT OF GRAVITY ON THE HEAD. 189 



right muscles, and they pull up the head erect again. 

 If the man's head falls to his left shoulder while he 

 is asleep, the nerve-centres for the right side of the 

 neck are not stimulated by the pull upon the muscles 

 sufficiently to make them contract. Here we appear 

 to have a case of reflex action which is lessened by 

 sleep, and is therefore an expression of the brain 

 condition sleepiness. The same principles apply to 

 falling of the head forward in flexion. 



It is useless to our purposes to say that con- 

 sciousness is a factor in the case, because we want 

 to lead up to an enumeration of the signs or expres- 

 sion of consciousness. We want to show that the 

 lessening of this reflex from the action of gravity is 

 an expression of the brain condition which produces 

 consciousness. I am not aware of any phenomena 

 concerning the upper extremity that are exactly 

 analogous to what has been just described concern- 

 ing the head. 



The head as a member of the body moved by the 

 nerve-centres is usually free or disengaged, but it is 

 not always so. It is not very free to afford ex- 

 pression to the emotions when a heavy load is being 

 carried on the head. It may also be engaged, and 

 not free, as the result of organic conditions, such as 

 the fixed position of the head in an attack of 

 spasmodic asthma. 



Applying the principle of contrast of the action 

 of small and large muscles, we should have to 

 compare movements of the eyes or facial muscles 

 with movements of the head. We may also com- 

 pare movements of the hands and head. Extension 



