DIRECTIVE INSTINCT 57 



pass through the brain, and we are not conscious 

 of them, and cannot perceive them. Its origin 

 has been attributed to the faculty of memory ; 

 it is supposed to represent a talent which has 

 been won by the trials, failures, and successes 

 of remote ancestors. But it displays a mys- 

 terious complicated acuteness for which this 

 hypothesis can in no way account. The female 

 Scolia a giant wasp of the Mediterranean 

 burrows underground, like a mole, until she 

 comes across the fat white grub of a rose-beetle 

 (Cetonia). By a sting accurately directed at the 

 meeting-place of the nerve ganglia she completely 

 paralyses it, leaving it alive but motionless. She 

 lays her egg upon its abdomen, so placed that 

 the young worm, on emerging, will find its mouth 

 against tissues that may be eaten without killing 

 the grub will, in fact, discover nourishment 

 which to a mammal is afforded by its mother's 

 breast. A peculiarly long snout enables it 

 searchingly to explore the body of its victim. So 

 it feeds during the fortnight of its larval stage, 

 but, guided by such discriminating skill as the 

 most practised dissector could not command, it 

 scrupulously avoids the nerves and vessels, 

 so as to spare the grub's life while draining it of 

 its substance. Did the grub die, the worm would 

 die also, for experiment has shown that dead tissue 

 poisons it. Here instinct displays not only its 

 passionless cruelty, but its mysterious insight and 

 its extraordinary skill. Could we bring ourselves 

 to believe that an insect can pass on its recollec- 

 tions of fortuitous successes as an inheritance to 

 its descendants, we should be no nearer an 

 explanation. It may possibly be contended that 

 the wasp may have discovered by accident, or by 

 trials, that the grub was useful, that it could 

 be hunted by burrowing, and might be paralysed 



