134 INTELLIGENT BEHAVIOUR 
Bembex, which does not store and close its cell, but brings 
continual supplies of food to its larva, is not disturbed by the 
presence in the cell of the grubs of the parasitic fly M/il/o- 
gramma. She could, we think, easily free her nest of these 
intruders, but she continues to bring supplies, though the 
parasites may absorb it all and leave her own larve to perish. 
She adapts her procedure to the new conditions, being in- 
capable of knowing that she is feeding the enemies of her 
race. 
Enough has now been said to show the extent and the 
limitations of the intelligence of such insects as the solitary 
wasps. It will be noticed that the acquired modifications of 
behaviour occur in close connection with the inherited ground- 
plan of instinctive procedure. We shall have occasion to note 
the same connection in our discussion of social behaviour in 
the next chapter. And we shall consider the influence of 
intelligence on instinct before we bring this chapter to a 
close. 
II].—Somst ReEsutts oF EXPERIMENT 
It is unnecessary to give a resume of entertaining anecdotes 
illustrative of intelligent behaviour in the higher animals. 
Such anecdotes are too often the outcome of casual observa- 
tions by untrained observers ; and the interpretation put upon 
the facts frequently shows a want of psychological discrimina- 
tion. Such is not the material of which science is constituted. 
What is needed is systematic observation conducted, so far as 
possible, under controlled conditions. ‘Two things are neces- 
sary : first, to distinguish instinctive behaviour, inherited as 
such, from the acquired modifications or new departures due 
to intelligence ; and secondly, to determine the method and 
range of intelligent procedure. These problems can only be 
solved in their entirety by a complete knowledge of the life- 
history of the animal concerned. But they may be attacked 
in detail by a systematic study of particular modes of behaviour, 
and by an investigation into their manner of origin. That 
