PREFACE 



come this obstacle and find a popular interpreta- 

 tion for our thoughts. The present little volume 

 is addressed to the widest circle of readers, even 

 to those who are as yet unacquainted with a 

 goodly number of excellent but much more volu- 

 minous works concerning the same subject. This 

 little work is reduced to such a size that it may 

 easily be perused in one leisure hour. Neverthe- 

 less I think that the facts which it presents will 

 furnish material for independent reflection in 

 serious hours. 



As for its scientific basis, I have only to men- 

 tion the name of Darwin. Whoever thinks him- 

 self beyond this name in our days is specially in- 

 vited to analyze his theories once more by the 

 help of this short and comprehensive sketch. In 

 its more intricate details my presentation of the 

 matter is naturally based on certain ideas of 

 Ernst Haeckel, but I must also give due credit to 

 the great influence which the more recent re- 

 searches of Herman Klaatsch of Heidelberg have 

 exerted upon me. Whenever I have ventured 

 beyond the line of facts, or combination of facts, 

 I have done so from my own firm conviction 

 that a thinking man is not dragged down by all 

 these relations with the animal world, but is 



