r72 THE DARWINIAN THEORY 



characters alone are preserved which are advan- 

 tageous to the species. 



Instinct. 



Two objections have been raised with regard to 

 instinct: (i) that it could not have been acquired 

 through Natural Selection ; (2) that it does not 

 benefit its possessors, and therefore that its pre- 

 servation is unintelligible. 



Let us consider some examples of instinct. The 

 eggs of butterflies and other insects are laid in 

 places as safe as possible and near to their future 

 food-supply. The butterfly never sees her young, 

 and, feeding on the juices of flowers, can have no 

 idea from her own experience as to the respective 

 merits of different leaves ; yet she makes no mistake. 

 Again, certain wasps sting the larvae of beetles, so as 



, to paralyse without killing them ; they then lay a 

 single egg on the paralysed victim and leave it to its 



! fate. The grub emerges and devours its prey, pass- 



/ ing the winter in the pupa stage and emerging in 

 the spring with the instincts of its parent. Here 

 the individual wasp derives no advantage, but the 

 gain to the species is enormous. 



Preservation of habit, or instinct, is due to the 



•fact that those individuals which take the greatest . 

 care to make provision for their young, will be most 

 likely to give rise to offspring which will survive in 

 jthe struggle for existence. Natural Selection will tend 

 to preserve the instinct because it is advantageous to 

 the species, although of no benefit to the individual. 



