THE BEHAVIOUR OF INSECTS 127 



insects is derived from simple reflex acts in which con- 

 sciousness plays no part. These constitute the raw 

 material, so to speak, from which more elaborate com- 

 binations, called instincts, have been built up through the 

 agency of natural selection, and transmitted as a kind of 

 self-acting nervous mechanism from one generation to 

 another. Broadly speaking, instincts are unaccommodating, 

 being performed in the same way by every member 

 of the species without regard to circumstances. But in 

 all insects, especially in the higher forms, there is a 

 tendency for instinct to be replaced by the fruit of 

 individual experience — i.e. by memory. Thus, while 

 instinct undoubtedly dominates the behaviour of insects, 

 it fails to account for every detail. In some of their 

 actions insects display a measure of intelligence. Beyond 

 this we cannot go. Between intelligence and rationality 

 there is a great gulf fixed, and no evidence exists to show 

 that it has been crossed by insects. Even ants, according 

 to the experiments of Lord Avebury, display profound 

 stupidity in face of novel emergencies which might easily 

 be circumvented by abstract reasoning of the simplest 

 kind. 



