BIOPSYCHOLOGICAL 621 



LiMiTEDNESS OF INSTINCT. — One of the pronounced character- 

 istics of instinctive behaviour, as contrasted with intelHgent be- 

 haviour, is its limitedness. While it may be in varying degrees 

 suffused with awareness and backed by endeavour, it evidently 

 does not include an intelligent appreciation of the situation. Thus 

 the animal may continue an instinctive activity after it has ceased 

 to be relevant, or may engage in some task which is futile because 

 premature. 



In some cases an animal has been misunderstood even by experts, 

 and called "unutterably stupid" because of its bewilderment before 

 some serious disturbance of the ordinary instinctive routine. 

 Whitman studied the varied behaviour of different kinds of pigeons 

 when the eggs were removed during the brooding bird's brief 

 absence and were placed a couple of inches or so outside the nest. 

 Some kinds retrieved the eggs, some were satisfied with one egg, 

 some made not the least effort to recover what had been removed 

 but sat patiently on nothing until the brooding instinct waned 

 away. But it is a mistake to think a creature stupid when it fails 

 to cope with the disturbance of a routine that is normally quite 

 instinctive. When a department of normal activity, such as brooding, 

 has been, so to speak, relegated to instinct, i.e. has come to be 

 adequately discharged by a chain of inborn neuro-muscular pre- 

 dispositions, and sometimes habituations as well, then it is appar- 

 ently difficult for intelligence to intervene, though it may be more 

 or less clearly exhibited in other situations where the animal is 

 untrammelled. 



A few examples of the limitations of instinctive behaviour may 

 be recalled. When the Procession Caterpillars, a plague of the 

 Mediterranean pine-woods, are full grown, they descend from the 

 trees and go on the march. They form an Indian file, head to tail, 

 and go straight on until they find earth soft enough to allow of 

 burrowing and pupation. Fabre adjusted the length of a file so that 

 it extended round the stone curb of a large circular water-basin in 

 his garden, and brought the head of A into contact with the tail 

 of Z. The well-known result was that they continued for a week 

 in futile circumambulation, when a little spice of judgment would 

 have broken the spell. Yet does not even man too often show 

 something of the like — enslaved by habituation, if not by 

 instinct ? 



So the lemmings on the march, obedient to their instinct to go 

 straight on, may swim out in large numbers into the sea and thus 

 meet their fate. So when the opening of the ground nest of the 

 common wasp is covered with a bell-jar, the imprisoned insects 

 never dig a passage out, though they readily could if they had the 

 sense to try. They are not physically imprisoned, but physiologically 

 and psychologically. Stragglers from outside may dig their way in, 



