Chapter xx 



THE MODERN THEORY OF INSTINCT 



The larv' ae of the various Hunting Wasps require 

 their prey to be incapable of movement, so that 

 there may be no resistance on the victim's part, 

 which would be a source of danger to the fragile 

 ^^g and, later, to the grub. Moreover, for all 

 its lethargy, it must still be alive ; for the grub 

 would refuse to feed on a corpse. The fare pro- 

 vided must be fresh meat and not preserved 

 stuff. I have already laid stress on these two 

 antagonistic conditions, immobility and life, 

 and enlarged on them so fully that I need hardly 

 dwell upon them for a second time. I have 

 shown how the Wasp realizes them by the 

 medium of a paralysis which destroys move- 

 ment and leaves the organic principle of life 

 intact. With a skill which our most famous 

 vivisectors would envy, the insect drives its 

 poisoned sting into the nerve-centres, the seat 

 of muscular incitation. The operator confines 

 herself to one stroke of the lancet, or else gives 

 two, three or more, according to the structure 



364 



