PREFACE, 
—+19— 
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 
question, no sphere of thought agitates the educated 
classes of our day so profoundly as the doctrine of de- 
scent. On both subjects the cry is, “Avow your colours!” 
