20 NATURE AND NURTURE 



with special stocks. I draw your attention first to one 

 in which great musical ability (the Bach family ^) (Plate II, 

 Fig. VI) has been prevalent for four or five generations. 

 In a second case (the Kemble-Siddons family ^) we have 

 the inheritance of great histrionic power through a number 

 of generations, not unaccompanied by marked ability in 

 other directions. See Plate II, Fig. vii. Lastly, the third 

 pedigree gives very marked scientific ability associated 

 with other forms of intellectual eminence in a remarkable 

 way. See Plate II, Fig. viii. 



Before I explain to you the manner in which this inten- 

 sity of heredity, this force of nature, is measured, I want 

 to emphasize once more the point from which I started, 

 namely, that in primitive society a harsh environment un- 

 doubtedly checks the survival of all forms of physical and 

 mental defect. Further, in civilized society all legislation 

 which provides nurture for the feebler at the cost of the 

 socially fitter must be detrimental to racial efficiency unless 

 (i) it is accompanied by some check to the reproduction of 

 the unfit, or (ii) we can show that nurture rather than nature 

 dominates the production of the mentally and physically 

 desirable members of our community. To the first 

 statement there can be no doubt of the answer that 

 must be given. Every improvement of environment has 

 lowered the death-rate and increased the net birth-rate 

 of the unfit. But associated with this, and possibly partly 

 due to it, has been a decreasing birth-rate of the fit. 

 I do not propose now to enter on the details of this, but 

 I will merely say that I regard it as demonstrated. I 

 propose rather to turn to my second question and ask 



^ Prepared by Amy Barrington. 



' Extended from a pedigree given by J. M. Bulloch in The Green 

 Room Book, 1910, p. 643. 



