APPENDIX D 223 



which, for convenience, we may regard as at opposite ends of 

 the scale, the dragon-fly and man. Tennyson's beautiful lines 

 occur to me. I quote from memory : — 



" To-day I saw the dragon-fly 

 Come from the wells where he did lie. 

 An inner impulse rent the veil 

 Of his old husk. From head to tail 

 Came out clear plates of sapphire mail. 

 He dried his wings ; like gauze they grew. 

 O'er crofts and pastures, wet with dew, 

 A living flash of light he flew." 



Physically, like other low animals, the dragon-fly does not 

 develop in response to exercise and use, or, if he does, it is to a 

 very small extent only compared to higher animals. Natural 

 selection has nicely co-ordinated his structures, but has not 

 evolved in them (at least to an appreciable extent) the power of 

 developing further, and in the right direction, during the changing 

 stress of circumstances. For example, his principal organs of 

 locomotion, his wings and the structures which subserve them, 

 are certainly wholly inborn. Mentally, at the beginning of each 

 stage of his existence he is able to co-ordinate his muscles per- 

 fectly, and thus at the beginning of each stage his locomotion is 

 apparently as good as at the end. Both in the water and in the 

 air he knows what food to seek, and what enemies to avoid, and 

 how to do so. At the fit time, impelled by an inborn impulse, 

 he leaves the water, and, having undergone his last meta- 

 morphosis, is able at once to adapt himself to life in an entirely 

 new environment, where the medium in which he exists, his 

 mode of locomotion, his prey, and his enemies are different, 

 and where his procreating instinct comes into activity. But 

 experience teaches him little or nothing ; he cannot acquire 

 mental traits ; in other words, he has little or no memory. 



Far different is the case with man. We have seen how much 

 he acquires physically, so that the adult differs from the infant 

 mainly in traits which he acquires, not in those which are inborn. 

 Mentally, his powers of acquirement are even more remarkable ; 



