PREFACE, 
THE present volume consists of essays which I have 
contributed to various periodicals, or read before scien- 
tific societies during the last fifteen years, with others 
now printed for the first time. The two first of the 
series are printed without alteration, because, having 
gained me the reputation of being an independent 
originator of the theory of “natural selection,’ they 
may be considered to have some historical value. I 
have added to them one or two very short explanatory 
notes, and have given headings to subjects, to make 
them uniform with the rest of the book. The other 
essays have been carefully corrected, often consider- 
ably enlarged, and in some cases almost rewritten, so 
as to express more fully and more clearly the views 
which I hold at the present time; and as most of 
them originally appeared in publications which have 
a very limited circulation, I believe that the larger 
portion of this volume will be new to many of my 
friends and to most of my readers. 
I now wish to say a few words on the reasons which 
have led me to publish this work. The second essay, 
especially when taken in connection with the first, 
contains an outline sketch of the theory of the origin 
of species (by means of what was afterwards termed 
by Mr. Darwin—‘ natural selection,”) as conceived 
1Dd1 2. 
