THE SELECTING POWER OF ENEMIES 47 
that all of its factors are parts of a continuous 
series. Therefore the selecting power of the 
environment will not be homogeneous but 
will be arranged through the environment, in 
the form of a continuous series. And as the 
individuals that go to form a species are not 
identical, but differ more or less from each, 
it follows that these variations of a species, 
a 
ir} 
Fig. 3. 
whether continuous or discontinuous, will 
TEND to become serially arranged through the 
specific environment, according to the serial 
arrangement of the selecting. power of the 
environment: as is shown in Fig. 3, V,, V,, 
V,-V, perfectly fitting E, E,, EE, If 
discontinuous there will be gaps. 
In Nature, this is prevented by inter- 
crossing (and migration). If the species were 
