vi CONTROLLED NATURAL SELECTION 
Theory of Sexual Selection. If therefore it 
could be shown that the origin of secondary 
sexual characters does not require this second 
Theory for their explanation, and if at the 
same time it can be shown that the origin 
of these characters is precisely similar to that 
of all characters: then the greater Theory, 
instead of being weakened by the Theory of 
Sexual Selection, will be strengthened by 
this widening of its capacity. This is the 
endeavour of the new Theory. 
It follows, therefore, that it has as a foun- 
dation—Darwin’s Theory of the Origin of 
Species, and thus it has support : but it is also 
open to all the many arguments which are 
levelled against this foundation. The Theory 
does not deal only with secondary sexual 
characters, but also with very many others 
which cause di- or poly-morphisms. The 
Theory is described as much as possible in 
simple language; technical words are when- 
ever possible avoided, in order that it may 
be intelligible to naturalists and field ob- 
servers, for it is their valuable work which 
is required for its substantiation or the re- 
verse. New terminologies are not introduced, 
although for descriptive purposes they would 
have been invaluable, because on account of 
