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 
“yropensity 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- 
