158 Instinct and Intelligence 



terminating in effective muscular and other 

 organs, by which energy is distributed to the 

 contractile elements of muscles, and to gland 

 cells. 



Energy derived from any object, such for 

 instance as a rose, passing to our retina releases 

 a part of the energy attached to its nervous 

 elements; the energy thus set free extends 

 along fibres to corresponding sensory cortical 

 centres, and is followed by a visual sensation 

 or feeling; at the same time the incoming 

 stream of energy makes an impression on some 

 of the mnemic elements of the sensory centre, 

 in the form of a visual image of the colour and 

 form of the flower. 



The visual, auditory, tactile, and other cor- 

 tical centres, however, are constituent parts of 

 the cerebral hemispheres which possess psychical 

 functions. When the potential energy of a 

 sensory centre is liberated by the re-excitation 

 of its charged or impressed elements, part of 

 its energy is liberated and sets free from sur- 

 rounding association centres a certain amount 

 of nerve force which gives reality to the sensa- 

 tion, that is to an idea of the form and colour 



