108 INSTINCT 



various influences from the environment which affect it. 

 It possesses a native fund of impulse which causes it to act 

 in more or less definite ways independently of the stimula- 

 tions of the outer world. Several modern writers have 

 over-emphasized the element of responsiveness in instinct, 

 as if an animal were like an instrument played upon by 

 outer forces and had its actions fatally determined by the 

 action of those forces on its own inner mechanism. Other 

 writers have treated instinct as determined by a sort of 

 internal impulsion. The latter conception is implied in the 

 German word "Trieb," or driving force, and in Paley's 

 "propensity prior to experience." Lloyd Morgan says in 

 speaking of instinct: "Initiated by an external stimulus 

 or group of stimuli, it is at any rate in many cases, deter- 

 mined also in greater degree than reflex action by an internal 

 factor which causes uneasiness or distress, more or less 

 marked, if it do not find its normal instinctive satisfactions. 

 Take, for example, the before mentioned instinct of the 

 great water-beetle to leave the pond and burrow in the bank 

 when the time for pupation is at hand. There is something 

 more here than a local response to an external stimulus; 

 something more, it would seem, than mere reflex action. 

 There are activities affecting the whole behavior of the 

 organism, and there seem to be internal promptings of some 

 kind due to organic conditions whose seat is in the body of 

 the developing larva. Or take the migration of birds, their 

 nest-building instincts, the activities involved in the rearing 

 of their young; there is surely, it may be said, something in 

 all this which may be distinguished, even if the line of de- 

 markation be hard to draw, from reflex action. We cannot 

 say more, however, than that the one is a more fully cor- 

 porate act than the other." 

 It is without question that internal states form the prompt- 



