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, 



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 2 , 

 V 3 -V n perfectly fitting E p E 2 , E 3 -E n . If 

 discontinuous there will be gaps. 



In Nature, this is prevented by inter- 

 crossing (and migration). If the species were 



