PREFACE. 
I T may be well at the outset clearly to define the posi 
tion taken in the following work. The author believes 
that the process of Organic Evolution has taken place, 
but he does not believe that Natural Selection has been 
the means by which that result has been brought about. 
If any reader is of opinion that Organic Evolution and 
Natural Selection are synonymous terms, he is recom 
mended at the outset to turn to the first chapter of the 
Third Book, in which it is attempted to show that Natural 
Selection is not identical with Organic Evolution. 
In the second place, the reader is warned against the 
idea that any selection in nature can properly be called 
Natural Selection. Natural Selection is a very complex 
term. It is based on the analogy supposed to exist 
between the process of artificial selection and a process 
which is supposed to take place in nature. In Natural 
Selection the struggle for existence is supposed to be 
the selecting power, and it works by life and death ; 
it secures the survival of the fittest, and hence it is 
based upon the principle of utility. It selects from those 
variations which are necessarily associated with sexual 
reproduction. It asks only for small variations, and it 
undertakes that the slight favourable variations shall 
survive. In this way it now produces the transmutation 
of species, and in a far-off past it was the only or