6i2 LIFE : OUTLINES OF GENERAL BIOLOGY 



narily stereotyped or obligatory; and it has often been remarked of 

 ants, bees, and wasps that hardly less wonderful than their achieve- 

 ments are their limitations. Thus the ready-made efficiency of in- 

 stinctive behaviour is apt to bring with it the handicap of tyrannous 

 adherence to routine. But this again must not be exaggerated, for 

 there are many instances of modified instinct, as when a spider 

 constructs a web in a peculiarly difficult situation, or when ants 

 are confronted with some artificial difficulty, such as a tarred band 

 around the bole of one of their trees. In such cases the probability 

 is that a spark of intelligence illuminates the situation, and so sets 

 the instinct free to its work again. 



Looked at ecologically, rather than physiologically, instinctive 

 behaviour is always related to particular circumstances, which are 

 either of frequent recurrence, or are such that an effective response 

 to them is of critical moment in the survival of individual or species. 

 Intelligence, as we have seen, implies some psychical appreciation 

 of relations, and is not necessarily definitised in its reference; but 

 instinct is always definitely related to particular circumstances. If 

 an ape has learned the use of a small lever, it may proceed to make 

 a large one ; but this intelligence is conspicuous by its absence in the 

 field of instinctive behaviour, the triumphs of which in honeycomb 

 and in wasp's nest, in the water-spider's sub-aquatic dome and in 

 the termite's tower, are none the less astounding. When we think 

 of the difficult problem of the evolution of an instinct, the particular 

 definiteness of its reference must be kept in mind. Whatever be our 

 theory of the origin of any of the marvellous instinctive capacities, 

 can we avoid the conclusion that it was tested by generations of 

 individuals in relation to a particular kind of environment and 

 need? 



But in varying degrees there is also a psychical aspect to instinctive 

 behaviour — a proposition which requires some proving. F"'or it will 

 not suffice to fall back on the more vague panpsychic proposition, 

 true though it be, that every integrated physiological sequence has 

 its psychic side. Evidence must be brought forward to show that 

 we cannot make sense of instinctive behaviour without postulating 

 a psychical factor. The chain of reflexes is suffused with an aware- 

 ness that is more than sensitiveness to stimuli, and backed by an 

 endeavour that is more than appetite. We may not be able to 

 demonstrate the reality of this psychical accompaniment as we 

 can demonstrate the electrical change that is associated with every 

 contraction of a muscle and every secretory activity of a gland. But 

 we must at least show that the psychic postulate is necessary for 

 clear thinking or adequate description. This involves the considera- 

 sion of numerous instances, and these we can only sample. 



To sum up so far: in instinctive behaviour we are dealing with a 

 range of activities that are predominantly the outcome of racial 



