60 Heredity, Variation and Genius 



times specially they evolve, yet Weismann and 

 his followers did, or do still, maintain that all 

 normally constituted persons are born with equal 

 capacities of mental growth, different results 

 being due to the environment in which they are 

 reared and grow to maturity. No doubt it would 

 be rash to underestimate the action of the environ- 

 ment on the reactions of organic life from its first 

 stages of development onwards, every phase 

 thereof being influenced by physical, chemical, 

 toxic and nutritive agencies, and in the human 

 case by the additional effective agencies of social 

 tradition, education, imitation and custom.* In- 

 deed, the effects upon individual mental develop- 

 ment which the training and circumstances of 

 life do manifestly exert fully justifies the suspicion 

 that much natural ability rests dormant in the 

 race for lack of suitable opportunity to elicit and 

 foster it. But when all is said it seems not less 

 certain that there are essential differences of 

 mentality which, not effaced, albeit sometimes 

 defaced, by a common training, urge their own 

 exercise and are educed by it. That which 

 education can do is to promote culture of self, 

 it can never effect its culture into another 

 self. Strongly and oftentimes ludicrously and 



* Experiments have shown how very small changes in the 

 salts composing seawater produce extraordinary abnormalities 

 in the development of the egg of the sea-urchin. For instance, 

 one part of lithium bromide in a thousand parts of water 

 produce great deformities at an early stage. 



