178 INTELLIGENT BEHAVIOUR 
be coincident in direction with the acquired habits. Thus 
would arise a congenital propensity to perform the habitual 
acts; and should they be of sufficient importance in the 
conduct of life to be subject to the action of natural selection, 
those animals in which such propensities were congenital 
would survive, whereas those in which no such propensities 
existed would be eliminated. It is unnecessary, however, to 
elaborate this conception further, since it is in line with that 
already discussed in considering the influence of intelligence in 
fostering a diversion of instinct under changing circumstances. 
Sufficient has now been said to illustrate some of the ways 
in which instinct and intelligence interact in the evolution of 
behaviour. Such interaction is further exemplified in the 
social life of animals, which will be dealt with in the next 
chapter. 
