viii EDITORS' PREFACE TO FIRST EDITION. 



Dr. van Rees of Amsterdam, to whom we desire to express 

 our most sincere thanks. The translation was laid aside 

 until the summer of 1888, when Mr. Shipley was invited to 

 co-operate 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 making 



valuable 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 greatl}^ 



helped us by looking over the proof-sheets \dth Professor 



Weismann. 



E. B. P. 



S. S. 



A. E. S. 

 Oxford, Febaiory, 1889. 



