74 PERIOD III. 



of the two will chase the quarry till it is out of breath, 

 when the other can take up the running on advantageous 

 terms. An old fox shows knowledge of the properties 

 of traps, and will rather make a new outlet or suffer 

 long famine than encounter them. But when he finds 

 a rabbit already caught, he realises that the trap has 

 lost its power to hurt. Sheep-dogs can be educated to 

 mind things which do not interest wild dogs, or dogs of 

 other breeds ; when, for instance, the flock is driven 

 past a patch of wheat, the dog in charge will take care 

 that the sheep do not damage the crop. A trained 

 sporting-dog learns at length to trust his own judgment, 

 even in opposition to that of his master, and sportsmen 

 know that they must direct young dogs, but leave old 

 ones to act for themselves. 



From the middle of the eighteenth century to the 

 present day naturalists and psychologists have been 

 labouring to distinguish instinct from intelligence. It 

 is not hard to define well-marked examples of each, and 

 to show that a typical instinct is congenital (not the 

 result of a process of education or self-education), 

 adaptive (conducive to the welfare of the organism), 

 co-ordinated by nerve-centres (thus excluding the 

 superficially similar behaviour of the lowest animals and 

 all plants), actuating the 'whole organism (thus excluding 

 most, if not all, reflex acts in the higher animals, as 

 well as the wonderful adjustments effected by bone- 

 corpuscles and other parts of organisms), and common 

 to all the members of a species or other group (thus 

 excluding individual apiitudes). 1 In the same way it 

 is easy to point out clear differences between a bird and 

 a tree. But just as a definition which shall separate 



1 Lloyd Morgan, Habit and Instinct, Introduction. 



