X KD1TOKS PREFACE. 



with the other editors in the preparation of the present volume ; 

 the Clarendon Press having consented to publish the complete 

 series of essays as one of their Foreign Biological Memoirs. 



We think it probable that this work may interest many who 

 are not trained biologists, but who approach the subject from its 

 philosophical or social aspects. Such readers would do well to 

 first study Essays I, II, VII, and VIII, inasmuch as some pre- 

 paration for the more technical treatment pursued in the other 

 essays will thus be gained. 



The notes signed A. W. and dated, were added by the author 

 during the progress of the translation. The notes included in 

 square brackets were added by the Editors ; the authorship being 

 indicated by initials in all cases. 



In conclusion, it is our pleasant duty to thank those who have 

 kindly helped us by reading the proof-sheets and makiog valu- 

 able suggestions. Our warmest thanks are due to Mrs. Arthur 

 Lyttelton, Mr. W. Hatchett Jackson, Deputy Linacre Professor 

 in the University of Oxford, Mr. J. S. Haldane, and Professor R. 

 Meldola. Important suggestions were also made by Professor 

 E. Ray Lankester, Mr. Francis Galton, and Dr. A. R. Wallace. 

 Professor W. N. Parker also greatly helped us by looking over 

 the proof-sheets with Professor Weismann. 



E. B. P. 



S. S. 

 A. E. S. 



OXFOKD, February, 1889. 



