CHAPTER IV 



THE INFLUENCES OF NUETURE 



§ 1. Nature and Nurture. — § 2. Nurture and Development. — 

 § 3. Individually Acquired Modifications and Their Trans- 

 missibility. — § 4. Nurture of the Higher Faculties. — § 5. 

 The Other Side of Heredity. 



§ 1. Nature and Nurture 



WHEN Charles First was King of England physi- 

 cians knew of the case of Jean Nougaret, who 

 sufered from night-blindness, or inability to see in faint 

 light. For more than two and a half centuries the 

 Nougaret family-history has been kept — we know of 

 2,000 individuals in ten generations — and the night- 

 blindness peculiarity has cropped up generation after 

 generation. Though no normal member of the lineage 

 has ever been the vehicle of handing on the defect, the 

 night-blindness has persisted through the abnormal 

 members. It may be absent from an individual, but it 

 does not disappear from the lineage. 



Similarly, most of us know of some peculiarity, such 

 as a curious shock of hair, persisting for several genera- 

 tions, or of a baby who is an almost grotesque cari- 

 cature of his grandfather. In cases like the last the 



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