PREFACE. 



THE three papers constituting this little brochure were originally 

 contributed to the Penn Monthly, and appeared in the April, 

 May, and July numbers of that magazine for 1 877. 



As the work which it was their more especial object to review 

 has not yet been placed before the non-German reading public, no 

 apology is offered for their reproduction in separate form. 



In view, however, of the popular interest which the views 

 of Prof. Haeckel have since called forth, and which seems to be 

 still increasing, it was thought an opportune moment for laying 

 before the general public this condensed exposition of the thought 

 and labors of the great naturalist and philosopher. 



It may further interest the reader to learn that Prof. Haeckel 



has acknowledged, in a private communication to the author, the 



substantial correctness with which these papers represent his 



position. 



L. F. W. 



Washington, March, 18 '79. 



