70 INSTINCTIVE BEHAVIOUR 
which is performed at or very shortly after birth. On the 
other hand, young swallows cannot fly at birth ; they are then 
too immature, and their wings are not sufficiently developed. 
But when they are some three weeks old, and the wings have 
attained functional size and power, little swallows can fly with 
considerable if not perfect skill. The co-ordination is con- 
genital, for it is not acquired in the course of individual 
experience ; but it is not connate, since it is not exhibited at 
or shortly after birth. The term deferred may be applied to 
such congenital activities as are thus carried out when the 
animal has undergone a certain amount of further develop- 
ment after birth. 
In the third place, it is customary to distinguish between 
such reflex actions as have already been briefly exemplified,* 
and instinctive behaviour. It is, however, by no means easy, 
if indeed it be possible, to draw any sharp and decisive line of 
demarcation. Instinct has indeed been well described by Mr. 
Herbert Spencer as compound reflex action ; hence the dis- 
tinction between instinctive. and reflex behaviour turns in 
large degree on their relative complexity. It would seem, 
however, that whereas a reflex act—such as the withdrawal of 
the foot of a sleeping child when the sole is tickled—is a 
restricted and localized response, involving a particular organ 
or a definite group of muscles, and is initiated by a more or 
less specialized external stimulus ; instinctive behaviour is a 
response of the animal as a whole, and involves the co-opera- 
tion of several organs and of many groups of muscles. Partly 
initiated by an external stimulus or group of stimuli, it is also, 
seemingly, determined in part, in a greater degree than reflex 
action, by internal factors which cause uneasiness or distress, 
more or less marked, if they do not find their normal in- 
stinctive satisfaction. This point, however, may be more 
profitably discussed in connection with the conscious aspect of 
instinct. If, then, we say that reflex acts are local responses of 
the congenital type due to specialized stimuli, while instinctive 
activities are matters of more general behaviour, usually 
* Chapter I., Section Y. 
