CHAPTER V 



INSTINCT 



Morphological characters which are of utility to a species m 

 the struggle for existence are due, as to their origin, to natural 

 selection, and are transmissible by heredity. Such characters 

 are, for instance, the colour of animals, and the varied and 

 delicate arrangements for the protection of plants from unwel- 

 come visitors. But psychological as well as morphological 

 characters can be thus selected and transmitted. And we shall 

 see that, unless certain morphological characters, certain animal 

 colours, were invariably associated with corresponding instincts, 

 those morphological characters would be useless to their pos- 

 sessor. There is thus a necessary correlation between the colour 

 and the instinct of the animal ; and even as the first is due to 

 natural selection — we speak now of protective colouring, as dis- 

 tinct from the decorations due to sexual selection — so also is 

 the second. 



Between reflex action and instinct no strict separation can be 

 established. On the other hand, a voluntary and conscious 

 action can, under certain circumstances, become instinctive.^ 

 Instinct, as Spencer has defined it, is a complex series of reflex 

 actions ; and, indeed, when we consider the extraordinary pre- 

 cision of the instincts in many of the lower animals, we are apt 

 to consider them from the human point of view, and to attribute 

 to their possessors psychical faculties analogous to those of man. 



' Vide in Chapter IV. the example of the walrus in the South Sea 

 Islands. 



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