2O Instinct and Intelligence 



that such behaviour is a more or less complex 

 organic or biological response to a more or less 

 complex group of stimuli of external and in- 

 ternal origin; and depends upon the inherited 

 structure of the nervous system of a definite 

 part of the brain. 



It would be difficult to devise a clearer defini- 

 tion of the term Instinct than that given by 

 Professor Lloyd Morgan; the nervous matter 

 through whose agency action of this kind is 

 brought into play is inherited. The energy 

 attached to its molecules being set free by vari- 

 ous stimuli received from external objects, and 

 internal movements becomes manifest in de- 

 finite action. That matter having instinctive 

 properties has been derived from a common 

 ancestral source, and has developed under the 

 laws of natural selection, is apparent from the 

 fact that the same kind of movements are made 

 in similar environmental conditions, without 

 being taught, by newly-born beings belonging 

 to the same species, located in widely separated 

 parts of the world. 



The exciting agent or mode of energy is 

 called a stimulus, which is always due to a 



