AUTHORS PREFACE. Vll 



greater part of the text I have looked through in proof, and I 

 believe that it well expresses the sense of the original ; although 

 naturally I cannot presume to judge concerning the niceties of 

 the English language. I am especially grateful to the three 

 gentlemen who have brought these essays before an English 

 public, because I believe that many English naturalists, even when 

 thoroughly conversant with the German tongue, might possibly 

 misinterpret many points in the original; for the difficulty of 

 the questions treated of greatly increases the difficulty of the 

 language. 



If the readers of this book only feel half as much pleasure in 

 its perusal as I experienced in writing it, I shall be more than 

 satisfied. 



AUGUST WEISMANN. 



FBEIBURG i. BREISGAU, 



January, 1889. 



b 2 



