SENSATIONS OF MOVEMENT AND POSITION 



649 



contracting muscle ensures in the best possible way that the organs should 

 be affected by the slightest change of tension of the muscle, and should 



pr.e. 



FIG. 321. A neuro-muscular spindle of the cat. (RUFFINI.) 

 c. capsule ; pr.e, primary ending ; s.e, secondary ending ; pl.e, plate ending 

 (all these are probably sensory in function). 



FIG. 322. Part of a muscle spindle more highly magnified. 

 n, nerve fibres passing to spindle ; a, annular endings of axis cylinders ; s. spiral 

 endings ; d, dendritic endings ; sh, connective-tissue sheath of spindle. (RUFFINI.) 



transmit information of the state of tension to the central nervous system. 



THE PSYCHOLOGICAL SIGNIFICANCE OF SENSATIONS OF MOVE- 

 MENT. Not only are these organic sensations of importance as affording 

 us information of the condition of our own bodies as distinct from the objects 

 in the world around, but they enter into and qualify our judgments derived 

 from all the sensations which arise in the special sense organs. 



When we regard the continuous aimless activity of a healthy baby, we 

 see that all ideas of space, of extension, of relative position are wanting, or at 

 any rate are not present to guide the npvements. Bit by bit muscular 

 experience is acquired. The child learns that a given movement of the right 

 arm will bring the hand in contact with something which is exciting the left 

 side of the retina. The surface of the thing, if of sufficient extension, can 

 excite tactile sensations in all the fingers of the right hand. By moving one 

 finger over the object the tactile sensations are found to be continuous; by 

 moving the whole hand forwards the thing is found to possess extension in 



