LESSONS OF EVOLUTION 611 



haps it is going too far to suggest that as regards our minds 

 we are more ' made ' than * born ' ; but this is certain, 

 that while our mental capacities are primarily determined 

 by heredity, they can be encouraged and augmented, or in- 

 hibited and depressed, within wide limits, by nurture. 



On no account are we to countenance, if we can help it, 

 spoiling good stock by bad, for that is the worst thing man 

 can do. But we must beware of confusing veneer with 

 hereditary nature. We must not too readily assume that 

 people are as good as they look, or as bad as they look. In 

 regard to the last, in an interesting study entitled Environ- 

 ment and Efficiency, Miss Mary Horner Thomson tells of 

 her investigation of 265 children, mostly of " the lowest 

 class" (Class A, fourth below the poverty level!), who had 

 been sent to institutions and trained. She found that 192 

 (72 per cent) turned out well; that 44 (16 per cent.) were 

 doubtful; and that only 29 (less than 11 per cent) were 

 unsatisfactory, and of these 13 were defective. These fig- 

 ures, which should of course be checked and extended, 

 afford some evidence of the controllability of the individual 

 life. 



Less extremely than some other Mendelians, Professor 

 Punnett writes : " Hygiene and education are influences 

 which can in some measure check the operation of one factor 

 and encourage the operation of another. But that they can 

 add a factor for a good quality or take away a factor for an 

 evil one is utterly opposed to all that is known of the facts 

 of heredity." 



But a practical note may be here permitted. It is very 

 difficult for us to know all that is in a man's inheritance. 

 Indeed we cannot, for we can see only what is expressed, 

 and the condition of expression is appropriate nurture. 



