TRANSLATOR'S PREFACE 



The quantity of popular evolutionary literature in our 

 tongue is — apart from works that deal with the subject 

 in its relation to religious controversy — so slight that 

 a fresh work of acknowledged competence should be 

 assured of a welcome. Professor Guenther's work 

 has, however, an especial title to consideration. He 

 has succeeded so well in taking up the position of the 

 average untrained observer for his instructive survey 

 of our animal world that his book will be singularly 

 helpful to thousands who shrink from the usual technical 

 manual. The reader will find himself at first looking 

 out on a familiar world in a familiar way. Gradually 

 he will find the well - known forms and movements 

 suggesting alluring problems to his opening vision, and 

 he will follow the answers to them, given with a logical 

 ease and literary grace that are too uncommon in this 

 department, almost without effort. 



Dr. Guenther's facility has not been purchased, as 

 often happens, at the expense of soundness or thorough- 

 ness. The limits of the work restrict his plan, but 

 within those limits the reader will feel that he is 

 following a judicious and entirely informed guide. 

 Though full reference is made to the most recent 

 speculations of biologists, it is not books and authorities, 

 but Nature, that the author holds steadily in view, 

 and his personal contributions to its interpretation will 



command respect. 



II 



