stages hi Human Evolution 



their relation to the hand, but peripheral rela- 

 tively to the trunk. ^ 



We usually begin any action or series of move- 

 ments with central muscles and complete it with 

 peripheral, so in picking up a pin from the floor 

 or going to the table for a pencil. Hence cen- 

 tral muscles have been called fundamental and 

 peripheral muscles accessory by some writers. 

 In fundamental movements of central muscles a 

 little nervous energy suffices to stimulate and 

 direct a large amount of muscular movement. 

 In the use of the accessory muscles of the fingers 

 the opposite is true In both respects. 



Our trunk muscles are capable of but few 

 simple movements, and these neither free nor 

 precise. Freedom, complexity, and precision of 

 movement Increases as we pass from trunk to 

 hand, and culminates In the fingers. 



The centers In the brain which control these 

 muscles show the same succession In age, and 

 differ correspondingly In structure. A few large 

 and powerful cells will suffice for the control of 

 the trunk muscles. Centers controlling the fin- 

 gers must contain many cells with very complex 



^ See Bibliography. 



37 



