PEE FACE. vii 



one effect of the evidence here collected will 

 be to strengthen the utmost claims I ever made 

 for the recognition of the importance of here- 

 ditary influence. 



A few of my results, and some of the evi- 

 dence on which they were based, were given 

 by me at a Friday evening lecture, Febru- 

 ary, 1874, before the Eoyal Institution. I 

 have incorporated parts of that lecture 

 into this volume, with emendations and large 

 additions. 



It had been my wish to work up the ma- 

 terials I possess with much minuteness ; but 

 some months of careful labour made it clear to 

 me that they were not sufficient to bear a more 

 strict or elaborate treatment than I have now 

 given to them. 



The pleasant duty remains of acknowledging 

 a debt to my friend, Mr. Herbert Spencer, for 

 many helpful suggestions, and for his encour- 

 agement when I was planning this work ; and to 

 reiterate my deep sense of gratitude to numerous 

 correspondents, which I have expressed else- 

 where in the following pages. 



