PREFACE. 



The important chapter which closes this work was 

 included in a public lecture which I delivered at the 

 meeting of Naturalists and Physicians held this year at 

 Wiesbaden; my purpose being, as I am willing to con- 

 fess, to ascertain, by experience, whether on this signifi- 

 cant subject I had struck the right note to suit a circle 

 of hearers and readers not hampered by prejudice. 



After the reception given to this fragment, which I 

 also issued in a separate pamphlet, under the title of 

 " The Doctrine of Descent, in its application to Man '' 

 (Die Anwendung der Descendenzlehre auf den Mens- 

 chen), I venture to hope that the whole may find a 

 welcome. 



With the exception of the Ecclesiastico-political ques- 

 tion, no sphere of thought agitates the educated classes 

 of our day so profoundly as the doctrine of descent. 

 On both subjects the cry is, " Avow your colours! " We 

 have,, therefore, endeavoured to define our standpoint 



