48 BASIS OF THE PEOBLEM 



among the Vertebrates, ' pheasants, plovers, moor-hen, domestic 

 chicks and duckhngs, with many others, are active soon after 

 birth, and exhibit powers of complex co-ordination, with little 

 or no practice of the necessary limb movements. They walk and 

 balance the body so soon and so well as to show that this mode 

 of procedure is congenital, and has not to be gradually acquired 

 through the guidance of experience. Young water birds swim 

 with neat orderly strokes the first time they are gently placed in 

 the water. Even little chicks a day or two old can swim well.' ^ 



Enough has been said in the way of illustration, as numerous 

 examples are familiar to every one. It is possible that instinctive 

 behaviour may have to be attributed to so lowly a group of 

 organisms as the flat worms. Instinct reaches its greatest 

 development among the insects, and some examples have been 

 given above of the amazingly intricate series of actions which are 

 performed by insects, under the guidance of instinct. There have 

 been two lines of mental evolution among animals, one culminat- 

 ing in the insects and the other in the Vertebrates. Among 

 the former instincts have become very specialized ; among the 

 latter they have remained far more generalized. Among the 

 latter again there has been a far higher development of intelligence 

 than among the former, thus further distinguishing the two 

 lines of mental evolution. It is probable, however, that intelli- 

 gence, though certainly at times in a very primitive form, always 

 accompanies instinct, and to the discussion of intelligence we 

 must now turn. 



8. We saw how as lowly an animal as an Infusorian can in 

 a sense learn from experience. It is only when learning from 

 experience reaches a more advanced stage that we speak of 

 intelligent action. If we watch one of the higher animals which, 

 under the influence of desire, is striving to satisfy this desire, 

 we find that it behaves in the following manner. An animal, 

 for instance, is shut up in a box with food outside. It is led by 

 instinct to all kinds of sporadic activities ; it will clutch and claw 

 and make every kind of effort to extricate itself. If some simple 

 catch has been contrived which opens the door and offers a way 

 of escape, the animal will probably sooner or later accidentally 

 operate the catch and escape. If the animal is replaced in the 

 box many times, it is found to escape on the average sooner. It 



* Lloyd Morgan, Animal Behaviour, p. 84. 



