AUTHOR S PREFACE TO FIRST EDITION. v 



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 natu- 

 ralists, 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. 



Freiburg i. Breisgau, 

 January, 1889. 



