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TEE POPULAR SCIENCE MONTHLY 



in arithmetic in school children, finds, as one sure principle of expla- 

 nation, the likeness of children to parents — and this even in subtle 

 traits and relations between traits, of whose very existence the parents 

 were not aware, and which the parents would not have known how to 

 nurture had they known of their existence. 



Dr. Keyes has recently made an elaborate study of various possible 

 causes of the rate of progress of a child through the elementary school. 

 He traces the effects of defective vision, of sickness, of moving from one 

 school to another, and so on, but finds nothing of great moment until he 

 happens to trace family relationships. Then it appears that certain 

 families are thick with " accelerates," or pupils who win double promo- 

 tions, whereas other families are thick with retarded pupils, who require 

 two years to complete a normal year's work. Of 168 families, only 30 

 contain both an " accelerated " and a " retarded " pupil, whereas 138 

 show either two or more accelerates or two or more retarded pupils. 

 The differences in home training are here not allowed for, but, in view 

 of what has been found in other cases, it appears certain that the rate 

 at which a child will progress in school in comparison with his fellows 

 is determined in large measure before he is born. 



In intellect and morals, as in bodily structure and features, men 

 differ, differ by original nature, and differ by families. There are 

 hereditary bonds by which one kind of intellect or character rather than 

 another is produced. Selective breeding can alter a man's capacity to 

 learn, to keep sane, to cherish justice or to be happy. 



Chart 5. Tub Improvement Possible by Sblectivb Breeding. The upper 

 surface being taken to represent the existing distribution of Intellect, the lower surface 

 represents what might be expected from, say, ten or twenty generations of breeding 

 exclusively from the apparently best tenth of human Intellects. 



